diff --git a/.travis.yml b/.travis.yml
index 5dc6cbaa..2827b522 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,8 @@
 language: node_js
 node_js:
+  - "12"
   - "10"
   - "8"
-  - "6"
 script: "npm run lint && npm run test-cover"
 # Send coverage data to Coveralls
 after_script: "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js"
diff --git a/README.md b/README.md
index 392b2261..034ab59f 100644
--- a/README.md
+++ b/README.md
@@ -152,7 +152,7 @@ Register a new middleware.
     before being committed to the database
   * `'commit'`: An operation was applied to a snapshot; The operation
     and new snapshot are about to be written to the database.
-  * `'afterSubmit'`: An operation was successfully submitted to
+  * `'afterWrite'`: An operation was successfully written to
     the database.
   * `'receive'`: Received a message from a client
   * `'reply'`: About to send a non-error reply to a client message
@@ -321,7 +321,7 @@ Populate the fields on `doc` with a snapshot of the document from the server.
 Populate the fields on `doc` with a snapshot of the document from the server, and
 fire events on subsequent changes.
 
-`doc.unsubscribe(function (err) {...})`	
+`doc.unsubscribe(function (err) {...})`
 Stop listening for document updates. The document data at the time of unsubscribing remains in memory, but no longer stays up-to-date. Resubscribe with `doc.subscribe`.
 
 `doc.ingestSnapshot(snapshot, callback)`
diff --git a/examples/counter/client.js b/examples/counter/client.js
index c8308ec4..1067d2a4 100644
--- a/examples/counter/client.js
+++ b/examples/counter/client.js
@@ -1,7 +1,8 @@
+var ReconnectingWebSocket = require('reconnecting-websocket');
 var sharedb = require('sharedb/lib/client');
 
 // Open WebSocket connection to ShareDB server
-var socket = new WebSocket('ws://' + window.location.host);
+var socket = new ReconnectingWebSocket('ws://' + window.location.host);
 var connection = new sharedb.Connection(socket);
 
 // Create local Doc instance mapped to 'examples' collection document with id 'counter'
diff --git a/examples/counter/package.json b/examples/counter/package.json
index 42b2e5c9..9c904f31 100644
--- a/examples/counter/package.json
+++ b/examples/counter/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sharedb-example-counter",
-  "version": "0.0.1",
+  "version": "1.0.0",
   "description": "A simple client/server app using ShareDB and WebSockets",
   "main": "server.js",
   "scripts": {
@@ -15,12 +15,13 @@
   ],
   "license": "MIT",
   "dependencies": {
+    "@teamwork/websocket-json-stream": "^2.0.0",
     "express": "^4.14.0",
+    "reconnecting-websocket": "^4.2.0",
     "sharedb": "^1.0.0-beta",
-    "@teamwork/websocket-json-stream": "^2.0.0",
-    "ws": "^1.1.0"
+    "ws": "^7.2.0"
   },
   "devDependencies": {
-    "browserify": "^13.0.1"
+    "browserify": "^16.5.0"
   }
 }
diff --git a/examples/leaderboard/README.md b/examples/leaderboard/README.md
index e3b52050..50562609 100644
--- a/examples/leaderboard/README.md
+++ b/examples/leaderboard/README.md
@@ -9,24 +9,16 @@ In this demo, data is not persisted. To persist data, run a Mongo
 server and initialize ShareDB with the
 [ShareDBMongo](https://github.com/share/sharedb-mongo) database adapter.
 
-## Run this example
-
-First, install dependencies.
-
-Note: Make sure you're in the `examples/leaderboard` folder so that it uses the `package.json` located here).
+## Install dependencies
 
+Make sure you're in the `examples/leaderboard` folder so that it uses the `package.json` located here).
 ```
 npm install
 ```
 
-Then build the client JavaScript file.
-```
-npm run build
-```
-
-Get the server running.
+## Build JavaScript bundle and run server
 ```
-npm start
+npm run build && npm start
 ```
 
 Finally, open the example app in the browser. It runs on port 8080 by default:
diff --git a/examples/leaderboard/client/Body.jsx b/examples/leaderboard/client/Body.jsx
index 80206ea3..1c68a6a1 100644
--- a/examples/leaderboard/client/Body.jsx
+++ b/examples/leaderboard/client/Body.jsx
@@ -1,19 +1,17 @@
 var React = require('react');
 var Leaderboard = require('./Leaderboard.jsx');
 
-var Body = React.createClass({
-  render: function() {
-    return (
-      <div className="app">
-        <div className="outer">
-          <div className="logo"></div>
-          <h1 className="title">Leaderboard</h1>
-          <div className="subtitle">Select a scientist to give them points</div>
-          <Leaderboard />
-        </div>
+function Body() {
+  return (
+    <div className="app">
+      <div className="outer">
+        <div className="logo"></div>
+        <h1 className="title">Leaderboard</h1>
+        <div className="subtitle">Select a scientist to give them points</div>
+        <Leaderboard />
       </div>
-    );
-  }
-});
+    </div>
+  );
+}
 
 module.exports = Body;
diff --git a/examples/leaderboard/client/Leaderboard.jsx b/examples/leaderboard/client/Leaderboard.jsx
index a3356f7c..f530ed14 100644
--- a/examples/leaderboard/client/Leaderboard.jsx
+++ b/examples/leaderboard/client/Leaderboard.jsx
@@ -4,15 +4,18 @@ var React = require('react');
 var _ = require('underscore');
 var connection = require('./connection');
 
-var Leaderboard = React.createClass({
-  getInitialState: function() {
-    return {
+class Leaderboard extends React.Component {
+  constructor(props) {
+    super(props);
+    this.state = {
       selectedPlayerId: null,
       players: []
     };
-  },
+    this.handlePlayerSelected = this.handlePlayerSelected.bind(this);
+    this.handleAddPoints = this.handleAddPoints.bind(this);
+  }
 
-  componentDidMount: function() {
+  componentDidMount() {
     var comp = this;
     var query = connection.createSubscribeQuery('players', {$sort: {score: -1}});
     query.on('ready', update);
@@ -21,30 +24,30 @@ var Leaderboard = React.createClass({
     function update() {
       comp.setState({players: query.results});
     }
-  },
+  }
 
-  componentWillUnmount: function() {
+  componentWillUnmount() {
     query.destroy();
-  },
+  }
 
-  selectedPlayer: function() {
+  selectedPlayer() {
     return _.find(this.state.players, function(x) {
       return x.id === this.state.selectedPlayerId;
     }.bind(this));
-  },
+  }
 
-  handlePlayerSelected: function(id) {
+  handlePlayerSelected(id) {
     this.setState({selectedPlayerId: id});
-  },
+  }
 
-  handleAddPoints: function() {
+  handleAddPoints() {
     var op = [{p: ['score'], na: 5}];
     connection.get('players', this.state.selectedPlayerId).submitOp(op, function(err) {
       if (err) { console.error(err); return; }
     });
-  },
+  }
 
-  render: function() {
+  render() {
     return (
       <div>
         <div className="leaderboard">
@@ -54,7 +57,7 @@ var Leaderboard = React.createClass({
       </div>
     );
   }
-});
+}
 
 module.exports = Leaderboard;
 
diff --git a/examples/leaderboard/client/Player.jsx b/examples/leaderboard/client/Player.jsx
index 2580bd11..f7c08e3f 100644
--- a/examples/leaderboard/client/Player.jsx
+++ b/examples/leaderboard/client/Player.jsx
@@ -1,18 +1,18 @@
+var PropTypes = require('prop-types');
 var React = require('react');
 var classNames = require('classnames');
 
-var Player = React.createClass({
-  propTypes: {
-    doc: React.PropTypes.object.isRequired,
-    onPlayerSelected: React.PropTypes.func.isRequired,
-    selected: React.PropTypes.bool.isRequired
-  },
+class Player extends React.Component {
+  constructor(props) {
+    super(props);
+    this.handleClick = this.handleClick.bind(this);
+  }
 
-  handleClick: function(event) {
+  handleClick(event) {
     this.props.onPlayerSelected(this.props.doc.id);
-  },
+  }
 
-  componentDidMount: function() {
+  componentDidMount() {
     var comp = this;
     var doc = comp.props.doc;
     doc.subscribe();
@@ -22,13 +22,13 @@ var Player = React.createClass({
       // `comp.props.doc.data` is now updated. re-render component.
       comp.forceUpdate();
     }
-  },
+  }
 
-  componentWillUnmount: function() {
+  componentWillUnmount() {
     this.doc.unsubscribe();
-  },
+  }
 
-  render: function() {
+  render() {
     var classes = {
       'player': true,
       'selected': this.props.selected
@@ -41,6 +41,12 @@ var Player = React.createClass({
       </li>
     );
   }
-});
+}
+
+Player.propTypes = {
+  doc: PropTypes.object.isRequired,
+  onPlayerSelected: PropTypes.func.isRequired,
+  selected: PropTypes.bool.isRequired
+};
 
 module.exports = Player;
diff --git a/examples/leaderboard/client/PlayerList.jsx b/examples/leaderboard/client/PlayerList.jsx
index 469ceef0..a7ea78b0 100644
--- a/examples/leaderboard/client/PlayerList.jsx
+++ b/examples/leaderboard/client/PlayerList.jsx
@@ -1,30 +1,29 @@
+var PropTypes = require('prop-types');
 var React = require('react');
 var Player = require('./Player.jsx');
 var _ = require('underscore');
 
-var PlayerList = React.createClass({
-  propTypes: {
-    players: React.PropTypes.array.isRequired,
-    selectedPlayerId: React.PropTypes.string
-  },
+function PlayerList(props) {
+  var { players, selectedPlayerId } = props;
+  var other = _.omit(props, 'players', 'selectedPlayerId');
 
-  render: function() {
-    var { players, selectedPlayerId } = this.props;
-    var other = _.omit(this.props, 'players', 'selectedPlayerId');
+  var playerNodes = players.map(function(player, index) {
+    var selected = selectedPlayerId === player.id;
 
-    var playerNodes = players.map(function(player, index) {
-      var selected = selectedPlayerId === player.id;
-
-      return (
-        <Player {...other} doc={player} key={player.id} selected={selected} />
-      );
-    });
     return (
-      <div className="playerList">
-        {playerNodes}
-      </div>
+      <Player {...other} doc={player} key={player.id} selected={selected} />
     );
-  }
-});
+  });
+  return (
+    <div className="playerList">
+      {playerNodes}
+    </div>
+  );
+}
+
+PlayerList.propTypes = {
+  players: PropTypes.array.isRequired,
+  selectedPlayerId: PropTypes.string
+};
 
-module.exports = PlayerList;
\ No newline at end of file
+module.exports = PlayerList;
diff --git a/examples/leaderboard/client/PlayerSelector.jsx b/examples/leaderboard/client/PlayerSelector.jsx
index 2a61d425..b778693a 100644
--- a/examples/leaderboard/client/PlayerSelector.jsx
+++ b/examples/leaderboard/client/PlayerSelector.jsx
@@ -1,24 +1,23 @@
+var PropTypes = require('prop-types');
 var React = require('react');
 
-var PlayerSelector = React.createClass({
-  propTypes: {
-    selectedPlayer: React.PropTypes.object
-  },
+function PlayerSelector({ selectedPlayer, onAddPoints }) {
+  var node;
 
-  render: function() {
-    var node;
+  if (selectedPlayer) {
+    node = <div className="details">
+      <div className="name">{selectedPlayer.data.name}</div>
+      <button className="inc" onClick={onAddPoints}>Add 5 points</button>
+    </div>;
+  } else {
+    node = <div className="message">Click a player to select</div>;
+  }
 
-    if (this.props.selectedPlayer) {
-      node = <div className="details">
-        <div className="name">{this.props.selectedPlayer.data.name}</div>
-        <button className="inc" onClick={this.props.onAddPoints}>Add 5 points</button>
-      </div>;
-    } else {
-      node = <div className="message">Click a player to select</div>;
-    }
+  return node;
+}
 
-    return node;
-  }
-});
+PlayerSelector.propTypes = {
+  selectedPlayer: PropTypes.object
+};
 
 module.exports = PlayerSelector;
diff --git a/examples/leaderboard/client/connection.js b/examples/leaderboard/client/connection.js
index a3c03eaa..a9001050 100644
--- a/examples/leaderboard/client/connection.js
+++ b/examples/leaderboard/client/connection.js
@@ -1,6 +1,7 @@
+var ReconnectingWebSocket = require('reconnecting-websocket');
 var sharedb = require('sharedb/lib/client');
 
 // Expose a singleton WebSocket connection to ShareDB server
-var socket = new WebSocket('ws://' + window.location.host);
+var socket = new ReconnectingWebSocket('ws://' + window.location.host);
 var connection = new sharedb.Connection(socket);
 module.exports = connection;
diff --git a/examples/leaderboard/package.json b/examples/leaderboard/package.json
index 6ee5782c..705cf66b 100644
--- a/examples/leaderboard/package.json
+++ b/examples/leaderboard/package.json
@@ -1,10 +1,10 @@
 {
   "name": "sharedb-example-leaderboard",
-  "version": "0.0.1",
+  "version": "1.0.0",
   "description": "React Leaderboard backed by ShareDB",
   "main": "server.js",
   "scripts": {
-    "build": "mkdir -p dist/ && ./node_modules/.bin/browserify -t [ babelify --presets [ react ] ] client/index.jsx -o dist/bundle.js",
+    "build": "mkdir -p static/dist/ && ./node_modules/.bin/browserify -t [ babelify --presets [ react ] ] client/index.jsx -o static/dist/bundle.js",
     "test": "echo \"Error: no test specified\" && exit 1",
     "start": "node server/index.js"
   },
@@ -15,21 +15,21 @@
   ],
   "license": "MIT",
   "dependencies": {
+    "@teamwork/websocket-json-stream": "^2.0.0",
     "classnames": "^2.2.5",
-    "connect": "^3.4.1",
-    "react": "^15.1.0",
-    "react-dom": "^15.1.0",
-    "serve-static": "^1.11.1",
+    "express": "^4.17.1",
+    "prop-types": "^15.7.2",
+    "react": "^16.11.0",
+    "react-dom": "^16.11.0",
+    "reconnecting-websocket": "^4.2.0",
     "sharedb": "^1.0.0-beta",
     "sharedb-mingo-memory": "^1.0.0-beta",
-    "through2": "^2.0.1",
     "underscore": "^1.8.3",
-    "@teamwork/websocket-json-stream": "^2.0.0",
-    "ws": "^1.1.0"
+    "ws": "^7.2.0"
   },
   "devDependencies": {
     "babel-preset-react": "^6.5.0",
     "babelify": "^7.3.0",
-    "browserify": "^13.0.1"
+    "browserify": "^16.5.0"
   }
 }
diff --git a/examples/leaderboard/server/index.js b/examples/leaderboard/server/index.js
index 6aebe997..242d9dd3 100644
--- a/examples/leaderboard/server/index.js
+++ b/examples/leaderboard/server/index.js
@@ -1,7 +1,6 @@
 var http = require('http');
 var ShareDB = require('sharedb');
-var connect = require('connect');
-var serveStatic = require('serve-static');
+var express = require('express');
 var ShareDBMingoMemory = require('sharedb-mingo-memory');
 var WebSocketJSONStream = require('@teamwork/websocket-json-stream');
 var WebSocket = require('ws');
@@ -10,8 +9,8 @@ var WebSocket = require('ws');
 var share = new ShareDB({db: new ShareDBMingoMemory()});
 
 // Create a WebSocket server
-var app = connect();
-app.use(serveStatic('.'));
+var app = express();
+app.use(express.static('static'));
 var server = http.createServer(app);
 var wss = new WebSocket.Server({server: server});
 server.listen(8080);
diff --git a/examples/leaderboard/index.html b/examples/leaderboard/static/index.html
similarity index 100%
rename from examples/leaderboard/index.html
rename to examples/leaderboard/static/index.html
diff --git a/examples/leaderboard/leaderboard.css b/examples/leaderboard/static/leaderboard.css
similarity index 100%
rename from examples/leaderboard/leaderboard.css
rename to examples/leaderboard/static/leaderboard.css
diff --git a/examples/rich-text/client.js b/examples/rich-text/client.js
index 68541137..5785357d 100644
--- a/examples/rich-text/client.js
+++ b/examples/rich-text/client.js
@@ -1,10 +1,11 @@
+var ReconnectingWebSocket = require('reconnecting-websocket');
 var sharedb = require('sharedb/lib/client');
 var richText = require('rich-text');
 var Quill = require('quill');
 sharedb.types.register(richText.type);
 
 // Open WebSocket connection to ShareDB server
-var socket = new WebSocket('ws://' + window.location.host);
+var socket = new ReconnectingWebSocket('ws://' + window.location.host);
 var connection = new sharedb.Connection(socket);
 
 // For testing reconnection
@@ -12,7 +13,7 @@ window.disconnect = function() {
   connection.close();
 };
 window.connect = function() {
-  var socket = new WebSocket('ws://' + window.location.host);
+  var socket = new ReconnectingWebSocket('ws://' + window.location.host);
   connection.bindToSocket(socket);
 };
 
diff --git a/examples/rich-text/package.json b/examples/rich-text/package.json
index 2249e29c..461a2260 100644
--- a/examples/rich-text/package.json
+++ b/examples/rich-text/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sharedb-example-rich-text",
-  "version": "0.0.1",
+  "version": "1.0.0",
   "description": "A simple rich-text editor example based on Quill and ShareDB",
   "main": "server.js",
   "scripts": {
@@ -14,14 +14,15 @@
   ],
   "license": "MIT",
   "dependencies": {
-    "express": "^4.14.0",
-    "quill": "^1.0.0-beta.11",
-    "rich-text": "^3.0.1",
-    "sharedb": "^1.0.0-beta",
     "@teamwork/websocket-json-stream": "^2.0.0",
-    "ws": "^1.1.0"
+    "express": "^4.17.1",
+    "quill": "^1.3.7",
+    "reconnecting-websocket": "^4.2.0",
+    "rich-text": "^4.0.0",
+    "sharedb": "^1.0.0-beta",
+    "ws": "^7.2.0"
   },
   "devDependencies": {
-    "browserify": "^13.0.1"
+    "browserify": "^16.5.0"
   }
 }
diff --git a/examples/textarea/client.js b/examples/textarea/client.js
index 4cbf5520..c5111c2b 100644
--- a/examples/textarea/client.js
+++ b/examples/textarea/client.js
@@ -2,8 +2,8 @@ var sharedb = require('sharedb/lib/client');
 var StringBinding = require('sharedb-string-binding');
 
 // Open WebSocket connection to ShareDB server
-var WebSocket = require('reconnecting-websocket');
-var socket = new WebSocket('ws://' + window.location.host);
+var ReconnectingWebSocket = require('reconnecting-websocket');
+var socket = new ReconnectingWebSocket('ws://' + window.location.host);
 var connection = new sharedb.Connection(socket);
 
 var element = document.querySelector('textarea');
diff --git a/examples/textarea/package.json b/examples/textarea/package.json
index 1a91a3aa..49c40f12 100644
--- a/examples/textarea/package.json
+++ b/examples/textarea/package.json
@@ -1,6 +1,6 @@
 {
   "name": "sharedb-example-textarea",
-  "version": "0.0.1",
+  "version": "1.0.0",
   "description": "A simple client/server app using ShareDB and WebSockets",
   "main": "server.js",
   "scripts": {
@@ -14,14 +14,14 @@
   ],
   "license": "MIT",
   "dependencies": {
-    "express": "^4.14.0",
-    "reconnecting-websocket": "^3.0.3",
+    "@teamwork/websocket-json-stream": "^2.0.0",
+    "express": "^4.17.1",
+    "reconnecting-websocket": "^4.2.0",
     "sharedb": "^1.0.0-beta",
     "sharedb-string-binding": "^1.0.0",
-    "@teamwork/websocket-json-stream": "^2.0.0",
-    "ws": "^1.1.0"
+    "ws": "^7.2.0"
   },
   "devDependencies": {
-    "browserify": "^13.0.1"
+    "browserify": "^16.5.0"
   }
 }
diff --git a/lib/agent.js b/lib/agent.js
index f548f4d7..9deb83d1 100644
--- a/lib/agent.js
+++ b/lib/agent.js
@@ -1,6 +1,6 @@
 var hat = require('hat');
-var util = require('./util');
 var types = require('./types');
+var util = require('./util');
 var logger = require('./logger');
 
 /**
@@ -105,8 +105,7 @@ Agent.prototype._subscribeToStream = function(collection, id, stream) {
       logger.error('Doc subscription stream error', collection, id, data.error);
       return;
     }
-    if (agent._isOwnOp(collection, data)) return;
-    agent._sendOp(collection, id, data);
+    agent._onOp(collection, id, data);
   });
   stream.on('end', function() {
     // The op stream is done sending, so release its reference
@@ -149,13 +148,41 @@ Agent.prototype._subscribeToQuery = function(emitter, queryId, collection, query
 
   emitter.onOp = function(op) {
     var id = op.d;
-    if (agent._isOwnOp(collection, op)) return;
-    agent._sendOp(collection, id, op);
+    agent._onOp(collection, id, op);
   };
 
   emitter._open();
 };
 
+Agent.prototype._onOp = function(collection, id, op) {
+  if (this._isOwnOp(collection, op)) return;
+
+  // Ops emitted here are coming directly from pubsub, which emits the same op
+  // object to listeners without making a copy. The pattern in middleware is to
+  // manipulate the passed in object, and projections are implemented the same
+  // way currently.
+  //
+  // Deep copying the op would be safest, but deep copies are very expensive,
+  // especially over arbitrary objects. This function makes a shallow copy of an
+  // op, and it requires that projections and any user middleware copy deep
+  // properties as needed when they modify the op.
+  //
+  // Polling of query subscriptions is determined by the same op objects. As a
+  // precaution against op middleware breaking query subscriptions, we delay
+  // before calling into projection and middleware code
+  var agent = this;
+  process.nextTick(function() {
+    var copy = shallowCopy(op);
+    agent.backend.sanitizeOp(agent, collection, id, copy, function(err) {
+      if (err) {
+        logger.error('Error sanitizing op emitted from subscription', collection, id, copy, err);
+        return;
+      }
+      agent._sendOp(collection, id, copy);
+    });
+  });
+};
+
 Agent.prototype._isOwnOp = function(collection, op) {
   // Detect ops from this client on the same projection. Since the client sent
   // these in, the submit reply will be sufficient and we can silently ignore
@@ -186,12 +213,17 @@ Agent.prototype._sendOp = function(collection, id, op) {
 
   this.send(message);
 };
-
 Agent.prototype._sendOps = function(collection, id, ops) {
   for (var i = 0; i < ops.length; i++) {
     this._sendOp(collection, id, ops[i]);
   }
 };
+Agent.prototype._sendOpsBulk = function(collection, opsMap) {
+  for (var id in opsMap) {
+    var ops = opsMap[id];
+    this._sendOps(collection, id, ops);
+  }
+};
 
 function getReplyErrorObject(err) {
   if (typeof err === 'string') {
@@ -201,7 +233,7 @@ function getReplyErrorObject(err) {
     };
   } else {
     if (err.stack) {
-      logger.warn(err.stack);
+      logger.info(err.stack);
     }
     return {
       code: err.code,
@@ -316,7 +348,8 @@ Agent.prototype._handleMessage = function(request, callback) {
       case 'u':
         return this._unsubscribe(request.c, request.d, callback);
       case 'op':
-        var op = this._createOp(request);
+        // Normalize the properties submitted
+        var op = createClientOp(request, this.clientId);
         if (!op) return callback({code: 4000, message: 'Invalid op message'});
         return this._submit(request.c, request.d, op, callback);
       case 'nf':
@@ -493,10 +526,7 @@ Agent.prototype._fetchBulkOps = function(collection, versions, callback) {
   var agent = this;
   this.backend.getOpsBulk(this, collection, versions, null, function(err, opsMap) {
     if (err) return callback(err);
-    for (var id in opsMap) {
-      var ops = opsMap[id];
-      agent._sendOps(collection, id, ops);
-    }
+    agent._sendOpsBulk(collection, opsMap);
     callback();
   });
 };
@@ -505,8 +535,18 @@ Agent.prototype._subscribe = function(collection, id, version, callback) {
   // If the version is specified, catch the client up by sending all ops
   // since the specified version
   var agent = this;
-  this.backend.subscribe(this, collection, id, version, function(err, stream, snapshot) {
+  this.backend.subscribe(this, collection, id, version, function(err, stream, snapshot, ops) {
     if (err) return callback(err);
+    // If we're subscribing from a known version, send any ops committed since
+    // the requested version to bring the client's doc up to date
+    if (ops) {
+      agent._sendOps(collection, id, ops);
+    }
+    // In addition, ops may already be queued on the stream by pubsub.
+    // Subscribe is called before the ops or snapshot are fetched, so it is
+    // possible that some ops may be duplicates. Clients should ignore any
+    // duplicate ops they may receive. This will flush ops already queued and
+    // subscribe to ongoing ops from the stream
     agent._subscribeToStream(collection, id, stream);
     // Snapshot is returned only when subscribing from a null version.
     // Otherwise, ops will have been pushed into the stream
@@ -519,9 +559,13 @@ Agent.prototype._subscribe = function(collection, id, version, callback) {
 };
 
 Agent.prototype._subscribeBulk = function(collection, versions, callback) {
+  // See _subscribe() above. This function's logic should match but in bulk
   var agent = this;
-  this.backend.subscribeBulk(this, collection, versions, function(err, streams, snapshotMap) {
+  this.backend.subscribeBulk(this, collection, versions, function(err, streams, snapshotMap, opsMap) {
     if (err) return callback(err);
+    if (opsMap) {
+      agent._sendOpsBulk(collection, opsMap);
+    }
     for (var id in streams) {
       agent._subscribeToStream(collection, id, streams[id]);
     }
@@ -572,45 +616,58 @@ Agent.prototype._submit = function(collection, id, op, callback) {
   });
 };
 
-function CreateOp(src, seq, v, create) {
+Agent.prototype._fetchSnapshot = function(collection, id, version, callback) {
+  this.backend.fetchSnapshot(this, collection, id, version, callback);
+};
+
+Agent.prototype._fetchSnapshotByTimestamp = function(collection, id, timestamp, callback) {
+  this.backend.fetchSnapshotByTimestamp(this, collection, id, timestamp, callback);
+};
+
+
+function createClientOp(request, clientId) {
+  // src can be provided if it is not the same as the current agent,
+  // such as a resubmission after a reconnect, but it usually isn't needed
+  var src = request.src || clientId;
+  // c, d, and m arguments are intentionally undefined. These are set later
+  return (request.op) ? new EditOp(src, request.seq, request.v, request.op) :
+    (request.create) ? new CreateOp(src, request.seq, request.v, request.create) :
+      (request.del) ? new DeleteOp(src, request.seq, request.v, request.del) :
+        undefined;
+}
+
+function shallowCopy(object) {
+  var out = {};
+  for (var key in object) {
+    out[key] = object[key];
+  }
+  return out;
+}
+
+function CreateOp(src, seq, v, create, c, d, m) {
   this.src = src;
   this.seq = seq;
   this.v = v;
   this.create = create;
-  this.m = null;
+  this.c = c;
+  this.d = d;
+  this.m = m;
 }
-function EditOp(src, seq, v, op) {
+function EditOp(src, seq, v, op, c, d, m) {
   this.src = src;
   this.seq = seq;
   this.v = v;
   this.op = op;
-  this.m = null;
+  this.c = c;
+  this.d = d;
+  this.m = m;
 }
-function DeleteOp(src, seq, v, del) {
+function DeleteOp(src, seq, v, del, c, d, m) {
   this.src = src;
   this.seq = seq;
   this.v = v;
   this.del = del;
-  this.m = null;
+  this.c = c;
+  this.d = d;
+  this.m = m;
 }
-// Normalize the properties submitted
-Agent.prototype._createOp = function(request) {
-  // src can be provided if it is not the same as the current agent,
-  // such as a resubmission after a reconnect, but it usually isn't needed
-  var src = request.src || this.clientId;
-  if (request.op) {
-    return new EditOp(src, request.seq, request.v, request.op);
-  } else if (request.create) {
-    return new CreateOp(src, request.seq, request.v, request.create);
-  } else if (request.del) {
-    return new DeleteOp(src, request.seq, request.v, request.del);
-  }
-};
-
-Agent.prototype._fetchSnapshot = function(collection, id, version, callback) {
-  this.backend.fetchSnapshot(this, collection, id, version, callback);
-};
-
-Agent.prototype._fetchSnapshotByTimestamp = function(collection, id, timestamp, callback) {
-  this.backend.fetchSnapshotByTimestamp(this, collection, id, timestamp, callback);
-};
diff --git a/lib/backend.js b/lib/backend.js
index bdac897f..42c20bd0 100644
--- a/lib/backend.js
+++ b/lib/backend.js
@@ -40,8 +40,8 @@ module.exports = Backend;
 emitter.mixin(Backend);
 
 Backend.prototype.MIDDLEWARE_ACTIONS = {
-  // An operation was successfully submitted to the database.
-  afterSubmit: 'afterSubmit',
+  // An operation was successfully written to the database.
+  afterWrite: 'afterWrite',
   // An operation is about to be applied to a snapshot before being committed to the database
   apply: 'apply',
   // An operation was applied to a snapshot; The operation and new snapshot are about to be written to the database.
@@ -154,7 +154,7 @@ Backend.prototype.use = function(action, fn) {
     for (var i = 0; i < action.length; i++) {
       this.use(action[i], fn);
     }
-    return;
+    return this;
   }
   var fns = this.middleware[action] || (this.middleware[action] = []);
   fns.push(fn);
@@ -199,7 +199,7 @@ Backend.prototype.submit = function(agent, index, id, op, options, callback) {
     if (err) return callback(err);
     request.submit(function(err) {
       if (err) return callback(err);
-      backend.trigger(backend.MIDDLEWARE_ACTIONS.afterSubmit, agent, request, function(err) {
+      backend.trigger(backend.MIDDLEWARE_ACTIONS.afterWrite, agent, request, function(err) {
         if (err) return callback(err);
         backend._sanitizeOps(agent, request.projection, request.collection, id, request.ops, function(err) {
           if (err) return callback(err);
@@ -211,6 +211,12 @@ Backend.prototype.submit = function(agent, index, id, op, options, callback) {
   });
 };
 
+Backend.prototype.sanitizeOp = function(agent, index, id, op, callback) {
+  var projection = this.projections[index];
+  var collection = (projection) ? projection.target : index;
+  this._sanitizeOp(agent, projection, collection, id, op, callback);
+};
+
 Backend.prototype._sanitizeOp = function(agent, projection, collection, id, op, callback) {
   if (projection) {
     try {
@@ -265,6 +271,28 @@ Backend.prototype._getSnapshotsFromMap = function(ids, snapshotMap) {
   return snapshots;
 };
 
+Backend.prototype._getSanitizedOps = function(agent, projection, collection, id, from, to, opsOptions, callback) {
+  var backend = this;
+  backend.db.getOps(collection, id, from, to, opsOptions, function(err, ops) {
+    if (err) return callback(err);
+    backend._sanitizeOps(agent, projection, collection, id, ops, function(err) {
+      if (err) return callback(err);
+      callback(null, ops);
+    });
+  });
+};
+
+Backend.prototype._getSanitizedOpsBulk = function(agent, projection, collection, fromMap, toMap, opsOptions, callback) {
+  var backend = this;
+  backend.db.getOpsBulk(collection, fromMap, toMap, opsOptions, function(err, opsMap) {
+    if (err) return callback(err);
+    backend._sanitizeOpsBulk(agent, projection, collection, opsMap, function(err) {
+      if (err) return callback(err);
+      callback(null, opsMap);
+    });
+  });
+};
+
 // Non inclusive - gets ops from [from, to). Ie, all relevant ops. If to is
 // not defined (null or undefined) then it returns all ops.
 Backend.prototype.getOps = function(agent, index, id, from, to, options, callback) {
@@ -285,13 +313,10 @@ Backend.prototype.getOps = function(agent, index, id, from, to, options, callbac
     to: to
   };
   var opsOptions = options && options.opsOptions;
-  backend.db.getOps(collection, id, from, to, opsOptions, function(err, ops) {
+  backend._getSanitizedOps(agent, projection, collection, id, from, to, opsOptions, function(err, ops) {
     if (err) return callback(err);
-    backend._sanitizeOps(agent, projection, collection, id, ops, function(err) {
-      if (err) return callback(err);
-      backend.emit('timing', 'getOps', Date.now() - start, request);
-      callback(err, ops);
-    });
+    backend.emit('timing', 'getOps', Date.now() - start, request);
+    callback(null, ops);
   });
 };
 
@@ -312,13 +337,10 @@ Backend.prototype.getOpsBulk = function(agent, index, fromMap, toMap, options, c
     toMap: toMap
   };
   var opsOptions = options && options.opsOptions;
-  backend.db.getOpsBulk(collection, fromMap, toMap, opsOptions, function(err, opsMap) {
+  backend._getSanitizedOpsBulk(agent, projection, collection, fromMap, toMap, opsOptions, function(err, opsMap) {
     if (err) return callback(err);
-    backend._sanitizeOpsBulk(agent, projection, collection, opsMap, function(err) {
-      if (err) return callback(err);
-      backend.emit('timing', 'getOpsBulk', Date.now() - start, request);
-      callback(err, opsMap);
-    });
+    backend.emit('timing', 'getOpsBulk', Date.now() - start, request);
+    callback(null, opsMap);
   });
 };
 
@@ -419,21 +441,25 @@ Backend.prototype.subscribe = function(agent, index, id, version, options, callb
   };
   backend.pubsub.subscribe(channel, function(err, stream) {
     if (err) return callback(err);
-    stream.initProjection(backend, agent, projection);
     if (version == null) {
       // Subscribing from null means that the agent doesn't have a document
       // and needs to fetch it as well as subscribing
       backend.fetch(agent, index, id, function(err, snapshot) {
-        if (err) return callback(err);
+        if (err) {
+          stream.destroy();
+          return callback(err);
+        }
         backend.emit('timing', 'subscribe.snapshot', Date.now() - start, request);
         callback(null, stream, snapshot);
       });
     } else {
-      backend.db.getOps(collection, id, version, null, null, function(err, ops) {
-        if (err) return callback(err);
-        stream.pushOps(collection, id, ops);
+      backend._getSanitizedOps(agent, projection, collection, id, version, null, null, function(err, ops) {
+        if (err) {
+          stream.destroy();
+          return callback(err);
+        }
         backend.emit('timing', 'subscribe.ops', Date.now() - start, request);
-        callback(null, stream);
+        callback(null, stream, null, ops);
       });
     }
   });
@@ -457,7 +483,6 @@ Backend.prototype.subscribeBulk = function(agent, index, versions, callback) {
     var channel = backend.getDocChannel(collection, id);
     backend.pubsub.subscribe(channel, function(err, stream) {
       if (err) return eachCb(err);
-      stream.initProjection(backend, agent, projection);
       streams[id] = stream;
       eachCb();
     });
@@ -478,17 +503,13 @@ Backend.prototype.subscribeBulk = function(agent, index, versions, callback) {
       });
     } else {
       // If a versions map, get ops since requested versions
-      backend.db.getOpsBulk(collection, versions, null, null, function(err, opsMap) {
+      backend._getSanitizedOpsBulk(agent, projection, collection, versions, null, null, function(err, opsMap) {
         if (err) {
           destroyStreams(streams);
           return callback(err);
         }
-        for (var id in opsMap) {
-          var ops = opsMap[id];
-          streams[id].pushOps(collection, id, ops);
-        }
         backend.emit('timing', 'subscribeBulk.ops', Date.now() - start, request);
-        callback(null, streams);
+        callback(null, streams, null, opsMap);
       });
     }
   });
@@ -530,7 +551,6 @@ Backend.prototype.querySubscribe = function(agent, index, query, options, callba
     }
     backend.pubsub.subscribe(request.channel, function(err, stream) {
       if (err) return callback(err);
-      stream.initProjection(backend, agent, request.projection);
       if (options.ids) {
         var queryEmitter = new QueryEmitter(request, stream, options.ids);
         backend.emit('timing', 'querySubscribe.reconnect', Date.now() - start, request);
diff --git a/lib/client/connection.js b/lib/client/connection.js
index 779b7138..521a8ceb 100644
--- a/lib/client/connection.js
+++ b/lib/client/connection.js
@@ -293,8 +293,15 @@ Connection.prototype._setState = function(newState, reason) {
   // 'connecting' from anywhere other than 'disconnected' and getting to
   // 'connected' from anywhere other than 'connecting'.
   if (
-    (newState === 'connecting' && this.state !== 'disconnected' && this.state !== 'stopped' && this.state !== 'closed')
-      || (newState === 'connected' && this.state !== 'connecting')
+    (
+      newState === 'connecting' &&
+      this.state !== 'disconnected' &&
+      this.state !== 'stopped' &&
+      this.state !== 'closed'
+    ) || (
+      newState === 'connected' &&
+      this.state !== 'connecting'
+    )
   ) {
     var err = new ShareDBError(5007, 'Cannot transition directly from ' + this.state + ' to ' + newState);
     return this.emit('error', err);
@@ -303,7 +310,13 @@ Connection.prototype._setState = function(newState, reason) {
   this.state = newState;
   this.canSend = (newState === 'connected');
 
-  if (newState === 'disconnected' || newState === 'stopped' || newState === 'closed') this._reset();
+  if (
+    newState === 'disconnected' ||
+    newState === 'stopped' ||
+    newState === 'closed'
+  ) {
+    this._reset();
+  }
 
   // Group subscribes together to help server make more efficient calls
   this.startBulk();
diff --git a/lib/op-stream.js b/lib/op-stream.js
index 3368c0dd..a2608fd2 100644
--- a/lib/op-stream.js
+++ b/lib/op-stream.js
@@ -5,12 +5,7 @@ var util = require('./util');
 // Stream of operations. Subscribe returns one of these
 function OpStream() {
   Readable.call(this, {objectMode: true});
-
   this.id = null;
-  this.backend = null;
-  this.agent = null;
-  this.projection = null;
-
   this.open = true;
 }
 module.exports = OpStream;
@@ -24,33 +19,15 @@ inherits(OpStream, Readable);
 // themselves.
 OpStream.prototype._read = util.doNothing;
 
-OpStream.prototype.initProjection = function(backend, agent, projection) {
-  this.backend = backend;
-  this.agent = agent;
-  this.projection = projection;
-};
-
-OpStream.prototype.pushOp = function(collection, id, op) {
-  if (this.backend) {
-    var stream = this;
-    this.backend._sanitizeOp(this.agent, this.projection, collection, id, op, function(err) {
-      if (!stream.open) return;
-      stream.push(err ? {error: err} : op);
-    });
-  } else {
-    // Ignore any messages after unsubscribe
-    if (!this.open) return;
-    this.push(op);
-  }
-};
-
-OpStream.prototype.pushOps = function(collection, id, ops) {
-  for (var i = 0; i < ops.length; i++) {
-    this.pushOp(collection, id, ops[i]);
-  }
+OpStream.prototype.pushData = function(data) {
+  // Ignore any messages after unsubscribe
+  if (!this.open) return;
+  // This data gets consumed in Agent#_subscribeToStream
+  this.push(data);
 };
 
 OpStream.prototype.destroy = function() {
+  // Only close stream once
   if (!this.open) return;
   this.open = false;
 
diff --git a/lib/pubsub/index.js b/lib/pubsub/index.js
index ff02ac00..e454a694 100644
--- a/lib/pubsub/index.js
+++ b/lib/pubsub/index.js
@@ -90,8 +90,7 @@ PubSub.prototype._emit = function(channel, data) {
   var channelStreams = this.streams[channel];
   if (channelStreams) {
     for (var id in channelStreams) {
-      var copy = shallowCopy(data);
-      channelStreams[id].pushOp(copy.c, copy.d, copy);
+      channelStreams[id].pushData(data);
     }
   }
 };
@@ -129,11 +128,3 @@ PubSub.prototype._removeStream = function(channel, stream) {
 
   this._unsubscribe(channel, this._defaultCallback);
 };
-
-function shallowCopy(object) {
-  var out = {};
-  for (var key in object) {
-    out[key] = object[key];
-  }
-  return out;
-}
diff --git a/lib/query-emitter.js b/lib/query-emitter.js
index fe5c5b01..cfa33884 100644
--- a/lib/query-emitter.js
+++ b/lib/query-emitter.js
@@ -1,5 +1,5 @@
 var arraydiff = require('arraydiff');
-var deepEquals = require('deep-is');
+var deepEqual = require('fast-deep-equal');
 var ShareDBError = require('./error');
 var util = require('./util');
 
@@ -63,7 +63,12 @@ QueryEmitter.prototype._emitTiming = function(action, start) {
 };
 
 QueryEmitter.prototype._update = function(op) {
+  // Note that `op` should not be projected or sanitized yet. It's possible for
+  // a query to filter on a field that's not in the projection. skipPoll checks
+  // to see if an op could possibly affect a query, so it should get passed the
+  // full op. The onOp listener function must call backend.sanitizeOp()
   var id = op.d;
+  var pollCallback = this._defaultCallback;
 
   // Check if the op's id matches the query before updating the query results
   // and send it through immediately if it does. The current snapshot
@@ -90,24 +95,35 @@ QueryEmitter.prototype._update = function(op) {
   // that removed the doc from the query to cause the client-side computed
   // list to update.
   if (this.ids.indexOf(id) !== -1) {
-    this.onOp(op);
+    var emitter = this;
+    pollCallback = function(err) {
+      // Send op regardless of polling error. Clients handle subscription to ops
+      // on the documents that currently match query results independently from
+      // updating which docs match the query
+      emitter.onOp(op);
+      if (err) emitter.onError(err);
+    };
   }
 
   // Ignore if the database or user function says we don't need to poll
   try {
-    if (this.db.skipPoll(this.collection, id, op, this.query)) return this._defaultCallback();
-    if (this.skipPoll(this.collection, id, op, this.query)) return this._defaultCallback();
+    if (
+      this.db.skipPoll(this.collection, id, op, this.query) ||
+      this.skipPoll(this.collection, id, op, this.query)
+    ) {
+      return pollCallback();
+    }
   } catch (err) {
-    return this._defaultCallback(err);
+    return pollCallback(err);
   }
   if (this.canPollDoc) {
     // We can query against only the document that was modified to see if the
     // op has changed whether or not it matches the results
-    this.queryPollDoc(id, this._defaultCallback);
+    this.queryPollDoc(id, pollCallback);
   } else {
     // We need to do a full poll of the query, because the query uses limits,
     // sorts, or something special
-    this.queryPoll(this._defaultCallback);
+    this.queryPoll(pollCallback);
   }
 };
 
@@ -173,7 +189,7 @@ QueryEmitter.prototype.queryPoll = function(callback) {
     emitter._emitTiming('queryEmitter.poll', start);
 
     // Be nice to not have to do this in such a brute force way
-    if (!deepEquals(emitter.extra, extra)) {
+    if (!deepEqual(emitter.extra, extra)) {
       emitter.extra = extra;
       emitter.onExtra(extra);
     }
diff --git a/package.json b/package.json
index b30da817..56a6d272 100644
--- a/package.json
+++ b/package.json
@@ -1,29 +1,29 @@
 {
   "name": "sharedb",
-  "version": "1.0.0-beta.23",
+  "version": "1.0.0-beta.27",
   "description": "JSON OT database backend",
   "main": "lib/index.js",
   "dependencies": {
     "arraydiff": "^0.1.1",
     "async": "^1.4.2",
-    "deep-is": "^0.1.3",
+    "fast-deep-equal": "^2.0.1",
     "hat": "0.0.3",
     "make-error": "^1.1.1",
     "ot-json0": "^1.0.1"
   },
   "devDependencies": {
-    "coveralls": "^2.11.8",
-    "eslint": "^5.16.0",
-    "eslint-config-google": "^0.13.0",
-    "expect.js": "^0.3.1",
-    "istanbul": "^0.4.2",
-    "lolex": "^3.0.0",
-    "mocha": "^5.2.0",
-    "sinon": "^6.1.5"
+    "chai": "^4.2.0",
+    "coveralls": "^3.0.7",
+    "eslint": "^6.5.1",
+    "eslint-config-google": "^0.14.0",
+    "lolex": "^5.1.1",
+    "mocha": "^6.2.2",
+    "nyc": "^14.1.1",
+    "sinon": "^7.5.0"
   },
   "scripts": {
     "test": "./node_modules/.bin/mocha && npm run lint",
-    "test-cover": "node_modules/istanbul/lib/cli.js cover node_modules/mocha/bin/_mocha",
+    "test-cover": "node_modules/nyc/bin/nyc.js --temp-dir=coverage -r text -r lcov node_modules/mocha/bin/_mocha && npm run lint",
     "lint": "./node_modules/.bin/eslint --ignore-path .gitignore '**/*.js'",
     "lint:fix": "npm run lint -- --fix"
   },
diff --git a/test/BasicQueryableMemoryDB.js b/test/BasicQueryableMemoryDB.js
new file mode 100644
index 00000000..85d1ca51
--- /dev/null
+++ b/test/BasicQueryableMemoryDB.js
@@ -0,0 +1,91 @@
+var MemoryDB = require('../lib/db/memory');
+
+module.exports = BasicQueryableMemoryDB;
+
+// Extension of MemoryDB that supports query filters and sorts on simple
+// top-level properties, which is enough for the core ShareDB tests on
+// query subscription updating.
+function BasicQueryableMemoryDB() {
+  MemoryDB.apply(this, arguments);
+}
+BasicQueryableMemoryDB.prototype = Object.create(MemoryDB.prototype);
+BasicQueryableMemoryDB.prototype.constructor = BasicQueryableMemoryDB;
+
+BasicQueryableMemoryDB.prototype._querySync = function(snapshots, query) {
+  if (query.filter) {
+    snapshots = snapshots.filter(function(snapshot) {
+      return querySnapshot(snapshot, query);
+    });
+  }
+
+  if (query.sort) {
+    if (!Array.isArray(query.sort)) {
+      throw new Error('query.sort must be an array');
+    }
+    if (query.sort.length) {
+      snapshots.sort(snapshotComparator(query.sort));
+    }
+  }
+
+  return {snapshots: snapshots};
+};
+
+BasicQueryableMemoryDB.prototype.queryPollDoc = function(collection, id, query, options, callback) {
+  var db = this;
+  process.nextTick(function() {
+    var snapshot = db._getSnapshotSync(collection, id);
+    try {
+      var matches = querySnapshot(snapshot, query);
+    } catch (err) {
+      return callback(err);
+    }
+    callback(null, matches);
+  });
+};
+
+BasicQueryableMemoryDB.prototype.canPollDoc = function(collection, query) {
+  return !query.sort;
+};
+
+function querySnapshot(snapshot, query) {
+  // Never match uncreated or deleted snapshots
+  if (snapshot.type == null) return false;
+  // Match any snapshot when there is no query filter
+  if (!query.filter) return true;
+  // Check that each property in the filter equals the snapshot data
+  for (var queryKey in query.filter) {
+    // This fake only supports simple property equality filters, so
+    // throw an error on Mongo-like filter properties with dots.
+    if (queryKey.includes('.')) {
+      throw new Error('Only simple property filters are supported, got:', queryKey);
+    }
+    if (snapshot.data[queryKey] !== query.filter[queryKey]) {
+      return false;
+    }
+  }
+  return true;
+}
+
+// sortProperties is an array whose items are each [propertyName, direction].
+function snapshotComparator(sortProperties) {
+  return function(snapshotA, snapshotB) {
+    for (var i = 0; i < sortProperties.length; i++) {
+      var sortProperty = sortProperties[i];
+      var sortKey = sortProperty[0];
+      var sortDirection = sortProperty[1];
+
+      var aPropVal = snapshotA.data[sortKey];
+      var bPropVal = snapshotB.data[sortKey];
+      if (aPropVal < bPropVal) {
+        return -1 * sortDirection;
+      } else if (aPropVal > bPropVal) {
+        return sortDirection;
+      } else if (aPropVal === bPropVal) {
+        continue;
+      } else {
+        throw new Error('Could not compare ' + aPropVal + ' and ' + bPropVal);
+      }
+    }
+    return 0;
+  };
+}
diff --git a/test/backend.js b/test/backend.js
index 991c6716..c6177d05 100644
--- a/test/backend.js
+++ b/test/backend.js
@@ -1,5 +1,5 @@
 var Backend = require('../lib/backend');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 
 describe('Backend', function() {
   var backend;
@@ -39,8 +39,8 @@ describe('Backend', function() {
         backend.getOps(null, 'books', '1984', 0, null, options, function(error, ops) {
           if (error) return done(error);
           expect(ops).to.have.length(2);
-          expect(ops[0].m).to.be.ok();
-          expect(ops[1].m).to.be.ok();
+          expect(ops[0].m).to.be.ok;
+          expect(ops[1].m).to.be.ok;
           done();
         });
       });
@@ -64,7 +64,7 @@ describe('Backend', function() {
         };
         backend.fetch(null, 'books', '1984', options, function(error, doc) {
           if (error) return done(error);
-          expect(doc.m).to.be.ok();
+          expect(doc.m).to.be.ok;
           done();
         });
       });
@@ -74,7 +74,7 @@ describe('Backend', function() {
       it('subscribes to the document', function(done) {
         backend.subscribe(null, 'books', '1984', null, function(error, stream, snapshot) {
           if (error) return done(error);
-          expect(stream.open).to.be(true);
+          expect(stream.open).to.equal(true);
           expect(snapshot.data).to.eql({
             title: '1984',
             author: 'George Orwell'
@@ -95,7 +95,7 @@ describe('Backend', function() {
           opsOptions: {metadata: true}
         };
         backend.subscribe(null, 'books', '1984', null, options, function(error) {
-          expect(error.code).to.be(4025);
+          expect(error.code).to.equal(4025);
           done();
         });
       });
diff --git a/test/client/connection.js b/test/client/connection.js
index b38ff53f..a7a6cd82 100644
--- a/test/client/connection.js
+++ b/test/client/connection.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var Backend = require('../../lib/backend');
 var Connection = require('../../lib/client/connection');
 
@@ -69,7 +69,7 @@ describe('client connection', function() {
         expect(originalStream).to.have.property('open', false);
         var newStream = agent.subscribedDocs[collection][docId];
         expect(newStream).to.have.property('open', true);
-        expect(newStream).to.not.be(originalStream);
+        expect(newStream).to.not.equal(originalStream);
         connection.close();
         done();
       });
diff --git a/test/client/doc.js b/test/client/doc.js
index 9b5316e3..fd0e255a 100644
--- a/test/client/doc.js
+++ b/test/client/doc.js
@@ -1,5 +1,5 @@
 var Backend = require('../../lib/backend');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var util = require('../util');
 
 describe('Doc', function() {
@@ -229,7 +229,7 @@ describe('Doc', function() {
     it('succeeds with valid op', function(done) {
       var doc = this.doc;
       doc.create({name: 'Scooby Doo'}, function(error) {
-        expect(error).to.not.be.ok();
+        expect(error).to.not.exist;
         // Build valid op that deletes a substring at index 0 of name.
         var textOpComponents = [{p: 0, d: 'Scooby '}];
         var op = [{p: ['name'], t: 'text0', o: textOpComponents}];
@@ -244,12 +244,12 @@ describe('Doc', function() {
     it('fails with invalid op', function(done) {
       var doc = this.doc;
       doc.create({name: 'Scooby Doo'}, function(error) {
-        expect(error).to.not.be.ok();
+        expect(error).to.not.exist;
         // Build op that tries to delete an invalid substring at index 0 of name.
         var textOpComponents = [{p: 0, d: 'invalid'}];
         var op = [{p: ['name'], t: 'text0', o: textOpComponents}];
         doc.submitOp(op, function(error) {
-          expect(error).to.be.ok();
+          expect(error).instanceOf(Error);
           done();
         });
       });
@@ -286,7 +286,7 @@ describe('Doc', function() {
       util.callInSeries([
         function(next) {
           doc.submitOp(invalidOp, function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             next();
           });
         },
diff --git a/test/client/pending.js b/test/client/pending.js
index 2b22c7a0..bfe84ddd 100644
--- a/test/client/pending.js
+++ b/test/client/pending.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var Backend = require('../../lib/backend');
 
 describe('client connection', function() {
diff --git a/test/client/projections.js b/test/client/projections.js
index 77359563..8b06c9d0 100644
--- a/test/client/projections.js
+++ b/test/client/projections.js
@@ -1,7 +1,10 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var util = require('../util');
 
-module.exports = function() {
+module.exports = function(options) {
+  var getQuery = options.getQuery;
+  var matchAllQuery = getQuery({query: {}});
+
   describe('client projections', function() {
     beforeEach(function(done) {
       this.backend.addProjection('dogs_summary', 'dogs', {age: true, owner: true});
@@ -26,7 +29,7 @@ module.exports = function() {
     ['createFetchQuery', 'createSubscribeQuery'].forEach(function(method) {
       it('snapshot ' + method, function(done) {
         var connection2 = this.backend.connect();
-        connection2[method]('dogs_summary', {}, null, function(err, results) {
+        connection2[method]('dogs_summary', matchAllQuery, null, function(err, results) {
           if (err) return done(err);
           expect(results.length).eql(1);
           expect(results[0].data).eql({age: 3, owner: {name: 'jim'}});
@@ -139,7 +142,7 @@ module.exports = function() {
           if (err) return done(err);
           connection.get('dogs', 'fido').submitOp(op, function(err) {
             if (err) return done(err);
-            connection2.createFetchQuery('dogs_summary', {}, null, function(err) {
+            connection2.createFetchQuery('dogs_summary', matchAllQuery, null, function(err) {
               if (err) return done(err);
               expect(fido.data).eql(expected);
               expect(fido.version).eql(2);
@@ -156,7 +159,7 @@ module.exports = function() {
         var connection = this.connection;
         var connection2 = this.backend.connect();
         var fido = connection2.get('dogs_summary', 'fido');
-        connection2.createSubscribeQuery('dogs_summary', {}, null, function(err) {
+        connection2.createSubscribeQuery('dogs_summary', matchAllQuery, null, function(err) {
           if (err) return done(err);
           fido.on('op', function() {
             expect(fido.data).eql(expected);
@@ -194,7 +197,7 @@ module.exports = function() {
       function test(trigger, callback) {
         var connection = this.connection;
         var connection2 = this.backend.connect();
-        var query = connection2.createSubscribeQuery('dogs_summary', {}, null, function(err) {
+        var query = connection2.createSubscribeQuery('dogs_summary', matchAllQuery, null, function(err) {
           if (err) return callback(err);
           query.on('insert', function() {
             callback(null, query.results);
@@ -203,6 +206,30 @@ module.exports = function() {
         });
       }
       queryUpdateTests(test);
+
+      it('query subscribe on projection will update based on fields not in projection', function(done) {
+        // Create a query on a field not in the projection. The query doesn't
+        // match the doc created in beforeEach
+        var fido = this.connection.get('dogs', 'fido');
+        var connection2 = this.backend.connect();
+        var dbQuery = getQuery({query: {color: 'black'}});
+        var query = connection2.createSubscribeQuery('dogs_summary', dbQuery, null, function(err, results) {
+          if (err) return done(err);
+          expect(results).to.have.length(0);
+
+          // Submit an op on a field not in the projection, where the op should
+          // cause the doc to be included in the query results
+          fido.submitOp({p: ['color'], od: 'gold', oi: 'black'}, null, function(err) {
+            if (err) return done(err);
+            setTimeout(function() {
+              expect(query.results).to.have.length(1);
+              expect(query.results[0].id).to.equal('fido');
+              expect(query.results[0].data).to.eql({age: 3, owner: {name: 'jim'}});
+              done();
+            }, 10);
+          });
+        });
+      });
     });
 
     describe('fetch query', function() {
@@ -211,7 +238,7 @@ module.exports = function() {
         var connection2 = this.backend.connect();
         trigger(connection, function(err) {
           if (err) return callback(err);
-          connection2.createFetchQuery('dogs_summary', {}, null, callback);
+          connection2.createFetchQuery('dogs_summary', matchAllQuery, null, callback);
         });
       }
       queryUpdateTests(test);
@@ -240,7 +267,7 @@ module.exports = function() {
         projected.fetch(function(err) {
           if (err) return done(err);
           projected.submitOp(op, function(err) {
-            expect(err).ok();
+            expect(err).instanceOf(Error);
             doc.fetch(function(err) {
               if (err) return done(err);
               expect(doc.data).eql({age: 3, color: 'gold', owner: {name: 'jim'}, litter: {count: 4}});
@@ -318,7 +345,7 @@ module.exports = function() {
         var projected = this.backend.connect().get('dogs_summary', 'spot');
         var data = {age: 5, foo: 'bar'};
         projected.create(data, function(err) {
-          expect(err).ok();
+          expect(err).instanceOf(Error);
           doc.fetch(function(err) {
             if (err) return done(err);
             expect(doc.data).eql(undefined);
diff --git a/test/client/query-subscribe.js b/test/client/query-subscribe.js
index 166c859e..8667fc81 100644
--- a/test/client/query-subscribe.js
+++ b/test/client/query-subscribe.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var async = require('async');
 var util = require('../util');
 
@@ -83,6 +83,40 @@ module.exports = function(options) {
       });
     });
 
+    it('subscribed query removes document from results before sending delete op to other clients', function(done) {
+      var connection1 = this.backend.connect();
+      var connection2 = this.backend.connect();
+      var matchAllDbQuery = this.matchAllDbQuery;
+      async.parallel([
+        function(cb) {
+          connection1.get('dogs', 'fido').create({age: 3}, cb);
+        },
+        function(cb) {
+          connection1.get('dogs', 'spot').create({age: 5}, cb);
+        }
+      ], function(err) {
+        if (err) return done(err);
+        var query = connection2.createSubscribeQuery('dogs', matchAllDbQuery, null, function(err) {
+          if (err) return done(err);
+          connection1.get('dogs', 'fido').del();
+        });
+        var removed = false;
+        connection2.get('dogs', 'fido').on('del', function() {
+          expect(removed).equal(true);
+          done();
+        });
+        query.on('remove', function(docs, index) {
+          removed = true;
+          expect(util.pluck(docs, 'id')).eql(['fido']);
+          expect(util.pluck(docs, 'data')).eql([{age: 3}]);
+          expect(index).a('number');
+          var results = util.sortById(query.results);
+          expect(util.pluck(results, 'id')).eql(['spot']);
+          expect(util.pluck(results, 'data')).eql([{age: 5}]);
+        });
+      });
+    });
+
     it('subscribed query does not get updated after destroyed', function(done) {
       var connection = this.backend.connect();
       var connection2 = this.backend.connect();
@@ -202,7 +236,9 @@ module.exports = function(options) {
         });
         query.on('remove', function(docs) {
           expect(util.pluck(docs, 'id')).eql(['fido']);
-          expect(util.pluck(docs, 'data')).eql([undefined]);
+          // We don't assert the value of data, because the del op could be
+          // applied by the client before or after the query result is removed.
+          // Order of ops & query result updates is not currently guaranteed
           finish();
         });
       });
diff --git a/test/client/query.js b/test/client/query.js
index 785c5521..b6efc1a2 100644
--- a/test/client/query.js
+++ b/test/client/query.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var async = require('async');
 var util = require('../util');
 
diff --git a/test/client/snapshot-timestamp-request.js b/test/client/snapshot-timestamp-request.js
index 8d7cc4bf..445c53d8 100644
--- a/test/client/snapshot-timestamp-request.js
+++ b/test/client/snapshot-timestamp-request.js
@@ -1,5 +1,5 @@
 var Backend = require('../../lib/backend');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var util = require('../util');
 var lolex = require('lolex');
 var MemoryDb = require('../../lib/db/memory');
@@ -183,7 +183,7 @@ describe('SnapshotTimestampRequest', function() {
         backend.connect().fetchSnapshotByTimestamp('books', 'time-machine', undefined, function() {});
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('throws without a callback', function() {
@@ -191,7 +191,7 @@ describe('SnapshotTimestampRequest', function() {
         backend.connect().fetchSnapshotByTimestamp('books', 'time-machine');
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('throws if the timestamp is -1', function() {
@@ -199,7 +199,7 @@ describe('SnapshotTimestampRequest', function() {
         backend.connect().fetchSnapshotByTimestamp('books', 'time-machine', -1, function() { });
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('errors if the timestamp is a string', function() {
@@ -207,7 +207,7 @@ describe('SnapshotTimestampRequest', function() {
         backend.connect().fetchSnapshotByTimestamp('books', 'time-machine', 'foo', function() { });
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('returns an empty snapshot if trying to fetch a non-existent document', function(done) {
@@ -229,11 +229,11 @@ describe('SnapshotTimestampRequest', function() {
 
       connection.fetchSnapshotByTimestamp('books', 'time-machine', null, function(error) {
         if (error) return done(error);
-        expect(connection.hasPending()).to.be(false);
+        expect(connection.hasPending()).to.equal(false);
         done();
       });
 
-      expect(connection.hasPending()).to.be(true);
+      expect(connection.hasPending()).to.equal(true);
     });
 
     it('deletes the request from the connection', function(done) {
@@ -269,7 +269,7 @@ describe('SnapshotTimestampRequest', function() {
       });
 
       connection.whenNothingPending(function() {
-        expect(snapshotFetched).to.be(true);
+        expect(snapshotFetched).to.equal(true);
         done();
       });
     });
@@ -328,7 +328,7 @@ describe('SnapshotTimestampRequest', function() {
         backend.use(backend.MIDDLEWARE_ACTIONS.readSnapshots,
           function(request) {
             expect(request.snapshots[0]).to.eql(v3);
-            expect(request.snapshotType).to.be(backend.SNAPSHOT_TYPES.byTimestamp);
+            expect(request.snapshotType).to.equal(backend.SNAPSHOT_TYPES.byTimestamp);
             done();
           }
         );
@@ -346,7 +346,7 @@ describe('SnapshotTimestampRequest', function() {
 
         backend.connect().fetchSnapshotByTimestamp('books', 'time-machine', function(error, snapshot) {
           if (error) return done(error);
-          expect(snapshot.data.title).to.be('Alice in Wonderland');
+          expect(snapshot.data.title).to.equal('Alice in Wonderland');
           done();
         });
       });
@@ -359,7 +359,7 @@ describe('SnapshotTimestampRequest', function() {
         ];
 
         backend.connect().fetchSnapshotByTimestamp('books', 'time-machine', day1, function(error) {
-          expect(error.message).to.be('foo');
+          expect(error.message).to.equal('foo');
           done();
         });
       });
@@ -374,8 +374,8 @@ describe('SnapshotTimestampRequest', function() {
         backend.connect().fetchSnapshotByTimestamp('bookTitles', 'time-machine', day2, function(error, snapshot) {
           if (error) return done(error);
 
-          expect(snapshot.data.title).to.be('The Time Machine');
-          expect(snapshot.data.author).to.be(undefined);
+          expect(snapshot.data.title).to.equal('The Time Machine');
+          expect(snapshot.data.author).to.equal(undefined);
           done();
         });
       });
@@ -441,11 +441,11 @@ describe('SnapshotTimestampRequest', function() {
           .fetchSnapshotByTimestamp('books', 'mocking-bird', halfwayBetweenDays3and4, function(error, snapshot) {
             if (error) return done(error);
 
-            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.be(true);
-            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.be(true);
-            expect(db.getOps.calledWith('books', 'mocking-bird', 2, 4)).to.be(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.equal(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.equal(true);
+            expect(db.getOps.calledWith('books', 'mocking-bird', 2, 4)).to.equal(true);
 
-            expect(snapshot.v).to.be(3);
+            expect(snapshot.v).to.equal(3);
             expect(snapshot.data).to.eql({title: 'To Kill a Mocking Bird', author: 'Harper Lee'});
             done();
           });
@@ -459,10 +459,10 @@ describe('SnapshotTimestampRequest', function() {
           .fetchSnapshotByTimestamp('books', 'mocking-bird', day2, function(error, snapshot) {
             if (error) return done(error);
 
-            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.be(true);
-            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.be(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.equal(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.equal(true);
 
-            expect(snapshot.v).to.be(2);
+            expect(snapshot.v).to.equal(2);
             expect(snapshot.data).to.eql({title: 'To Kill a Mocking Bird', author: 'Harper Lea'});
             done();
           });
@@ -477,11 +477,11 @@ describe('SnapshotTimestampRequest', function() {
           .fetchSnapshotByTimestamp('books', 'mocking-bird', day1, function(error, snapshot) {
             if (error) return done(error);
 
-            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.be(true);
-            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.be(true);
-            expect(db.getOps.calledWith('books', 'mocking-bird', 0, 2)).to.be(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.equal(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.equal(true);
+            expect(db.getOps.calledWith('books', 'mocking-bird', 0, 2)).to.equal(true);
 
-            expect(snapshot.v).to.be(1);
+            expect(snapshot.v).to.equal(1);
             expect(snapshot.data).to.eql({title: 'To Kill a Mocking Bird'});
             done();
           });
@@ -496,11 +496,11 @@ describe('SnapshotTimestampRequest', function() {
           .fetchSnapshotByTimestamp('books', 'mocking-bird', day5, function(error, snapshot) {
             if (error) return done(error);
 
-            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.be(true);
-            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.be(true);
-            expect(db.getOps.calledWith('books', 'mocking-bird', 4, null)).to.be(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrBeforeTime.calledOnce).to.equal(true);
+            expect(milestoneDb.getMilestoneSnapshotAtOrAfterTime.calledOnce).to.equal(true);
+            expect(db.getOps.calledWith('books', 'mocking-bird', 4, null)).to.equal(true);
 
-            expect(snapshot.v).to.be(5);
+            expect(snapshot.v).to.equal(5);
             expect(snapshot.data).to.eql({
               title: 'To Kill a Mocking Bird',
               author: 'Harper Lee',
diff --git a/test/client/snapshot-version-request.js b/test/client/snapshot-version-request.js
index a39355f3..e2155d45 100644
--- a/test/client/snapshot-version-request.js
+++ b/test/client/snapshot-version-request.js
@@ -1,5 +1,5 @@
 var Backend = require('../../lib/backend');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var MemoryDb = require('../../lib/db/memory');
 var MemoryMilestoneDb = require('../../lib/milestone-db/memory');
 var sinon = require('sinon');
@@ -105,7 +105,7 @@ describe('SnapshotVersionRequest', function() {
         backend.connect().fetchSnapshot('books', 'don-quixote', undefined, function() {});
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('fetches the latest version when the optional version is not provided', function(done) {
@@ -121,7 +121,7 @@ describe('SnapshotVersionRequest', function() {
         backend.connect().fetchSnapshot('books', 'don-quixote');
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('throws if the version is -1', function() {
@@ -129,7 +129,7 @@ describe('SnapshotVersionRequest', function() {
         backend.connect().fetchSnapshot('books', 'don-quixote', -1, function() {});
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('errors if the version is a string', function() {
@@ -137,13 +137,13 @@ describe('SnapshotVersionRequest', function() {
         backend.connect().fetchSnapshot('books', 'don-quixote', 'foo', function() { });
       };
 
-      expect(fetch).to.throwError();
+      expect(fetch).to.throw(Error);
     });
 
     it('errors if asking for a version that does not exist', function(done) {
       backend.connect().fetchSnapshot('books', 'don-quixote', 4, function(error, snapshot) {
-        expect(error.code).to.be(4024);
-        expect(snapshot).to.be(undefined);
+        expect(error.code).to.equal(4024);
+        expect(snapshot).to.equal(undefined);
         done();
       });
     });
@@ -167,11 +167,11 @@ describe('SnapshotVersionRequest', function() {
 
       connection.fetchSnapshot('books', 'don-quixote', null, function(error) {
         if (error) return done(error);
-        expect(connection.hasPending()).to.be(false);
+        expect(connection.hasPending()).to.equal(false);
         done();
       });
 
-      expect(connection.hasPending()).to.be(true);
+      expect(connection.hasPending()).to.equal(true);
     });
 
     it('deletes the request from the connection', function(done) {
@@ -207,7 +207,7 @@ describe('SnapshotVersionRequest', function() {
       });
 
       connection.whenNothingPending(function() {
-        expect(snapshotFetched).to.be(true);
+        expect(snapshotFetched).to.equal(true);
         done();
       });
     });
@@ -266,7 +266,7 @@ describe('SnapshotVersionRequest', function() {
         backend.use(backend.MIDDLEWARE_ACTIONS.readSnapshots,
           function(request) {
             expect(request.snapshots[0]).to.eql(v3);
-            expect(request.snapshotType).to.be(backend.SNAPSHOT_TYPES.byVersion);
+            expect(request.snapshotType).to.equal(backend.SNAPSHOT_TYPES.byVersion);
             done();
           }
         );
@@ -284,7 +284,7 @@ describe('SnapshotVersionRequest', function() {
 
         backend.connect().fetchSnapshot('books', 'don-quixote', function(error, snapshot) {
           if (error) return done(error);
-          expect(snapshot.data.title).to.be('Alice in Wonderland');
+          expect(snapshot.data.title).to.equal('Alice in Wonderland');
           done();
         });
       });
@@ -297,7 +297,7 @@ describe('SnapshotVersionRequest', function() {
         ];
 
         backend.connect().fetchSnapshot('books', 'don-quixote', 0, function(error) {
-          expect(error.message).to.be('foo');
+          expect(error.message).to.equal('foo');
           done();
         });
       });
@@ -312,8 +312,8 @@ describe('SnapshotVersionRequest', function() {
         backend.connect().fetchSnapshot('bookTitles', 'don-quixote', 2, function(error, snapshot) {
           if (error) return done(error);
 
-          expect(snapshot.data.title).to.be('Don Quixote');
-          expect(snapshot.data.author).to.be(undefined);
+          expect(snapshot.data.title).to.equal('Don Quixote');
+          expect(snapshot.data.author).to.equal(undefined);
           done();
         });
       });
@@ -435,9 +435,9 @@ describe('SnapshotVersionRequest', function() {
           backendWithMilestones.connect().fetchSnapshot('books', 'mocking-bird', 3, next);
         },
         function(snapshot, next) {
-          expect(milestoneDb.getMilestoneSnapshot.calledOnce).to.be(true);
-          expect(db.getOps.calledWith('books', 'mocking-bird', 2, 3)).to.be(true);
-          expect(snapshot.v).to.be(3);
+          expect(milestoneDb.getMilestoneSnapshot.calledOnce).to.equal(true);
+          expect(db.getOps.calledWith('books', 'mocking-bird', 2, 3)).to.equal(true);
+          expect(snapshot.v).to.equal(3);
           expect(snapshot.data).to.eql({title: 'To Kill a Mocking Bird', author: 'Harper Lee'});
           next();
         },
diff --git a/test/client/submit.js b/test/client/submit.js
index 2e47a444..f626f9eb 100644
--- a/test/client/submit.js
+++ b/test/client/submit.js
@@ -1,5 +1,5 @@
 var async = require('async');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var types = require('../../lib/types');
 var deserializedType = require('./deserialized-type');
 var numberType = require('./number-type');
@@ -96,7 +96,7 @@ module.exports = function() {
         if (err) return done(err);
         doc.version++;
         doc.submitOp({p: ['age'], na: 2}, function(err) {
-          expect(err).ok();
+          expect(err).instanceOf(Error);
           done();
         });
       });
@@ -105,7 +105,7 @@ module.exports = function() {
     it('cannot submit op on an uncreated doc', function(done) {
       var doc = this.backend.connect().get('dogs', 'fido');
       doc.submitOp({p: ['age'], na: 2}, function(err) {
-        expect(err).ok();
+        expect(err).instanceOf(Error);
         done();
       });
     });
@@ -113,7 +113,7 @@ module.exports = function() {
     it('cannot delete an uncreated doc', function(done) {
       var doc = this.backend.connect().get('dogs', 'fido');
       doc.del(function(err) {
-        expect(err).ok();
+        expect(err).instanceOf(Error);
         done();
       });
     });
@@ -207,7 +207,7 @@ module.exports = function() {
       doc.create({age: 3}, function(err) {
         if (err) return done(err);
         doc.create({age: 4}, function(err) {
-          expect(err).ok();
+          expect(err).instanceOf(Error);
           expect(doc.version).equal(1);
           expect(doc.data).eql({age: 3});
           done();
@@ -221,7 +221,7 @@ module.exports = function() {
       doc.create({age: 3}, function(err) {
         if (err) return done(err);
         doc2.create({age: 4}, function(err) {
-          expect(err).ok();
+          expect(err).instanceOf(Error);
           expect(doc2.version).equal(1);
           expect(doc2.data).eql({age: 3});
           done();
@@ -262,7 +262,7 @@ module.exports = function() {
           doc.submitOp({p: ['age'], na: 1}, function(err) {
             if (err) return done(err);
             doc2.submitOp({p: ['age'], na: 2}, function(err) {
-              expect(err).ok();
+              expect(err).instanceOf(Error);
               done();
             });
           });
@@ -287,7 +287,7 @@ module.exports = function() {
           doc.submitOp({p: ['age'], na: 1}, function(err) {
             if (err) return done(err);
             doc2.submitOp({p: ['age'], na: 2}, function(err) {
-              expect(err).ok();
+              expect(err).instanceOf(Error);
               done();
             });
           });
@@ -432,7 +432,7 @@ module.exports = function() {
           expect(doc.version).eql(1);
           expect(doc.data).eql({age: 3});
         } else {
-          expect(err).ok();
+          expect(err).instanceOf(Error);
           expect(doc.version).eql(1);
           expect(doc.data).eql({age: 5});
           done();
@@ -445,7 +445,7 @@ module.exports = function() {
           expect(doc2.version).eql(1);
           expect(doc2.data).eql({age: 5});
         } else {
-          expect(err).ok();
+          expect(err).instanceOf(Error);
           expect(doc2.version).eql(1);
           expect(doc2.data).eql({age: 3});
           done();
@@ -537,15 +537,15 @@ module.exports = function() {
               docCallback();
             }
           });
-          doc.submitOp({p: ['age'], na: 2}, function(error) {
-            if (error) return done(error);
+          doc.submitOp({p: ['age'], na: 2}, function(err) {
+            if (err) return done(err);
             // When we know the first op has been committed, we try to commit the second op, which will
             // fail because it's working on an out-of-date snapshot. It will retry, but exceed the
             // maxSubmitRetries limit of 0
             doc2Callback();
           });
-          doc2.submitOp({p: ['age'], na: 7}, function(error) {
-            expect(error).ok();
+          doc2.submitOp({p: ['age'], na: 7}, function(err) {
+            expect(err).instanceOf(Error);
             done();
           });
         });
@@ -616,7 +616,7 @@ module.exports = function() {
           doc2.del(function(err) {
             if (err) return done(err);
             doc.submitOp({p: ['age'], na: 1}, function(err) {
-              expect(err).ok();
+              expect(err).instanceOf(Error);
               expect(doc.version).equal(1);
               expect(doc.data).eql({age: 3});
               done();
@@ -1070,7 +1070,7 @@ module.exports = function() {
       doc.create({age: 3}, function(err) {
         if (err) return done(err);
         doc._submit({}, null, function(err) {
-          expect(err).ok();
+          expect(err).instanceOf(Error);
           done();
         });
       });
@@ -1094,8 +1094,9 @@ module.exports = function() {
         var doc = this.backend.connect().get('dogs', 'fido');
         doc.create([3], deserializedType.type.uri, function(err) {
           if (err) return done(err);
-          expect(doc.data).a(deserializedType.Node);
-          expect(doc.data).eql({value: 3, next: null});
+          expect(doc.data).instanceOf(deserializedType.Node);
+          expect(doc.data.value).equal(3);
+          expect(doc.data.next).equal(null);
           done();
         });
       });
@@ -1120,8 +1121,9 @@ module.exports = function() {
           if (err) return done(err);
           doc2.fetch(function(err) {
             if (err) return done(err);
-            expect(doc2.data).a(deserializedType.Node);
-            expect(doc2.data).eql({value: 3, next: null});
+            expect(doc2.data).instanceOf(deserializedType.Node);
+            expect(doc2.data.value).equal(3);
+            expect(doc2.data.next).equal(null);
             done();
           });
         });
@@ -1133,7 +1135,9 @@ module.exports = function() {
           if (err) return done(err);
           doc.submitOp({insert: 0, value: 2}, function(err) {
             if (err) return done(err);
-            expect(doc.data).eql({value: 2, next: {value: 3, next: null}});
+            expect(doc.data.value).eql(2);
+            expect(doc.data.next.value).equal(3);
+            expect(doc.data.next.next).equal(null);
             done();
           });
         });
@@ -1150,7 +1154,10 @@ module.exports = function() {
               if (err) return done(err);
               doc2.submitOp({insert: 1, value: 4}, function(err) {
                 if (err) return done(err);
-                expect(doc2.data).eql({value: 2, next: {value: 3, next: {value: 4, next: null}}});
+                expect(doc2.data.value).equal(2);
+                expect(doc2.data.next.value).equal(3);
+                expect(doc2.data.next.next.value).equal(4);
+                expect(doc2.data.next.next.next).equal(null);
                 done();
               });
             });
@@ -1164,8 +1171,9 @@ module.exports = function() {
         var doc = this.backend.connect().get('dogs', 'fido');
         doc.create([3], deserializedType.type2.uri, function(err) {
           if (err) return done(err);
-          expect(doc.data).a(deserializedType.Node);
-          expect(doc.data).eql({value: 3, next: null});
+          expect(doc.data).instanceOf(deserializedType.Node);
+          expect(doc.data.value).equal(3);
+          expect(doc.data.next).equal(null);
           done();
         });
       });
@@ -1174,8 +1182,9 @@ module.exports = function() {
         var doc = this.backend.connect().get('dogs', 'fido');
         doc.create(new deserializedType.Node(3), deserializedType.type2.uri, function(err) {
           if (err) return done(err);
-          expect(doc.data).a(deserializedType.Node);
-          expect(doc.data).eql({value: 3, next: null});
+          expect(doc.data).instanceOf(deserializedType.Node);
+          expect(doc.data.value).equal(3);
+          expect(doc.data.next).equal(null);
           done();
         });
       });
diff --git a/test/client/subscribe.js b/test/client/subscribe.js
index f1c3a63a..fe53e9c3 100644
--- a/test/client/subscribe.js
+++ b/test/client/subscribe.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var async = require('async');
 
 module.exports = function() {
@@ -339,7 +339,7 @@ module.exports = function() {
           doc.pause();
           var calls = 0;
           doc.create({age: 3}, function(err) {
-            expect(err).ok();
+            expect(err).instanceOf(Error);
             calls++;
           });
           doc[method](function(err) {
diff --git a/test/db-memory.js b/test/db-memory.js
index 0f0d01a9..e27ce0fe 100644
--- a/test/db-memory.js
+++ b/test/db-memory.js
@@ -1,6 +1,6 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var DB = require('../lib/db');
-var MemoryDB = require('../lib/db/memory');
+var BasicQueryableMemoryDB = require('./BasicQueryableMemoryDB');
 
 describe('DB base class', function() {
   it('can call db.close() without callback', function() {
@@ -16,7 +16,7 @@ describe('DB base class', function() {
   it('returns an error if db.commit() is unimplemented', function(done) {
     var db = new DB();
     db.commit('testcollection', 'test', {}, {}, null, function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       done();
     });
   });
@@ -24,7 +24,7 @@ describe('DB base class', function() {
   it('returns an error if db.getSnapshot() is unimplemented', function(done) {
     var db = new DB();
     db.getSnapshot('testcollection', 'foo', null, null, function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       done();
     });
   });
@@ -32,7 +32,7 @@ describe('DB base class', function() {
   it('returns an error if db.getOps() is unimplemented', function(done) {
     var db = new DB();
     db.getOps('testcollection', 'foo', 0, null, null, function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       done();
     });
   });
@@ -40,7 +40,7 @@ describe('DB base class', function() {
   it('returns an error if db.query() is unimplemented', function(done) {
     var db = new DB();
     db.query('testcollection', {x: 5}, null, null, function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       done();
     });
   });
@@ -48,75 +48,12 @@ describe('DB base class', function() {
   it('returns an error if db.queryPollDoc() is unimplemented', function(done) {
     var db = new DB();
     db.queryPollDoc('testcollection', 'foo', {x: 5}, null, function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       done();
     });
   });
 });
 
-
-// Extension of MemoryDB that supports query filters and sorts on simple
-// top-level properties, which is enough for the core ShareDB tests on
-// query subscription updating.
-function BasicQueryableMemoryDB() {
-  MemoryDB.apply(this, arguments);
-}
-BasicQueryableMemoryDB.prototype = Object.create(MemoryDB.prototype);
-BasicQueryableMemoryDB.prototype.constructor = BasicQueryableMemoryDB;
-
-BasicQueryableMemoryDB.prototype._querySync = function(snapshots, query) {
-  if (query.filter) {
-    snapshots = snapshots.filter(function(snapshot) {
-      for (var queryKey in query.filter) {
-        // This fake only supports simple property equality filters, so
-        // throw an error on Mongo-like filter properties with dots.
-        if (queryKey.includes('.')) {
-          throw new Error('Only simple property filters are supported, got:', queryKey);
-        }
-        if (snapshot.data[queryKey] !== query.filter[queryKey]) {
-          return false;
-        }
-      }
-      return true;
-    });
-  }
-
-  if (query.sort) {
-    if (!Array.isArray(query.sort)) {
-      throw new Error('query.sort must be an array');
-    }
-    if (query.sort.length) {
-      snapshots.sort(snapshotComparator(query.sort));
-    }
-  }
-
-  return {snapshots: snapshots};
-};
-
-// sortProperties is an array whose items are each [propertyName, direction].
-function snapshotComparator(sortProperties) {
-  return function(snapshotA, snapshotB) {
-    for (var i = 0; i < sortProperties.length; i++) {
-      var sortProperty = sortProperties[i];
-      var sortKey = sortProperty[0];
-      var sortDirection = sortProperty[1];
-
-      var aPropVal = snapshotA.data[sortKey];
-      var bPropVal = snapshotB.data[sortKey];
-      if (aPropVal < bPropVal) {
-        return -1 * sortDirection;
-      } else if (aPropVal > bPropVal) {
-        return sortDirection;
-      } else if (aPropVal === bPropVal) {
-        continue;
-      } else {
-        throw new Error('Could not compare ' + aPropVal + ' and ' + bPropVal);
-      }
-    }
-    return 0;
-  };
-}
-
 // Run all the DB-based tests against the BasicQueryableMemoryDB.
 require('./db')({
   create: function(options, callback) {
diff --git a/test/db.js b/test/db.js
index 701bdb7a..0fd9364b 100644
--- a/test/db.js
+++ b/test/db.js
@@ -1,5 +1,5 @@
 var async = require('async');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var Backend = require('../lib/backend');
 var ot = require('../lib/ot');
 
@@ -36,7 +36,7 @@ module.exports = function(options) {
       });
     });
 
-    require('./client/projections')();
+    require('./client/projections')({getQuery: getQuery});
     require('./client/query-subscribe')({getQuery: getQuery});
     require('./client/query')({getQuery: getQuery});
     require('./client/submit')();
@@ -87,7 +87,7 @@ module.exports = function(options) {
       function testCreateCommit(ops, snapshot) {
         expect(snapshot.v).eql(1);
         expect(ops.length).equal(1);
-        expect(ops[0].create).ok();
+        expect(ops[0].create).ok;
       }
 
       it('one commit succeeds from 2 simultaneous creates', function(done) {
@@ -117,8 +117,8 @@ module.exports = function(options) {
       function testOpCommit(ops, snapshot) {
         expect(snapshot.v).equal(2);
         expect(ops.length).equal(2);
-        expect(ops[0].create).ok();
-        expect(ops[1].op).ok();
+        expect(ops[0].create).ok;
+        expect(ops[1].op).ok;
       }
 
       function testDelCommit(ops, snapshot) {
@@ -126,7 +126,7 @@ module.exports = function(options) {
         expect(ops.length).equal(2);
         expect(snapshot.data).equal(undefined);
         expect(snapshot.type).equal(null);
-        expect(ops[0].create).ok();
+        expect(ops[0].create).ok;
         expect(ops[1].del).equal(true);
       }
 
@@ -734,7 +734,8 @@ module.exports = function(options) {
         var db = this.db;
         db.commit('testcollection', 'test', {v: 0, create: {}}, snapshot, null, function(err) {
           if (err) return done(err);
-          db.queryPoll('testcollection', {x: 5}, null, function(err, ids) {
+          var dbQuery = getQuery({query: {x: 5}});
+          db.queryPoll('testcollection', dbQuery, null, function(err, ids) {
             if (err) return done(err);
             expect(ids).eql(['test']);
             done();
@@ -743,7 +744,8 @@ module.exports = function(options) {
       });
 
       it('returns nothing when there is no data', function(done) {
-        this.db.queryPoll('testcollection', {x: 5}, null, function(err, ids) {
+        var dbQuery = getQuery({query: {x: 5}});
+        this.db.queryPoll('testcollection', dbQuery, null, function(err, ids) {
           if (err) return done(err);
           expect(ids).eql([]);
           done();
@@ -753,11 +755,11 @@ module.exports = function(options) {
 
     describe('queryPollDoc', function() {
       it('returns false when the document does not exist', function(done) {
-        var query = {};
-        if (!this.db.canPollDoc('testcollection', query)) return done();
+        var dbQuery = getQuery({query: {}});
+        if (!this.db.canPollDoc('testcollection', dbQuery)) return done();
 
         var db = this.db;
-        db.queryPollDoc('testcollection', 'doesnotexist', query, null, function(err, result) {
+        db.queryPollDoc('testcollection', 'doesnotexist', dbQuery, null, function(err, result) {
           if (err) return done(err);
           expect(result).equal(false);
           done();
@@ -765,14 +767,14 @@ module.exports = function(options) {
       });
 
       it('returns true when the document matches', function(done) {
-        var query = {x: 5};
-        if (!this.db.canPollDoc('testcollection', query)) return done();
+        var dbQuery = getQuery({query: {x: 5}});
+        if (!this.db.canPollDoc('testcollection', dbQuery)) return done();
 
         var snapshot = {type: 'json0', v: 1, data: {x: 5, y: 6}};
         var db = this.db;
         db.commit('testcollection', 'test', {v: 0, create: {}}, snapshot, null, function(err) {
           if (err) return done(err);
-          db.queryPollDoc('testcollection', 'test', query, null, function(err, result) {
+          db.queryPollDoc('testcollection', 'test', dbQuery, null, function(err, result) {
             if (err) return done(err);
             expect(result).equal(true);
             done();
@@ -781,14 +783,14 @@ module.exports = function(options) {
       });
 
       it('returns false when the document does not match', function(done) {
-        var query = {x: 6};
-        if (!this.db.canPollDoc('testcollection', query)) return done();
+        var dbQuery = getQuery({query: {x: 6}});
+        if (!this.db.canPollDoc('testcollection', dbQuery)) return done();
 
         var snapshot = {type: 'json0', v: 1, data: {x: 5, y: 6}};
         var db = this.db;
         db.commit('testcollection', 'test', {v: 0, create: {}}, snapshot, null, function(err) {
           if (err) return done(err);
-          db.queryPollDoc('testcollection', 'test', query, null, function(err, result) {
+          db.queryPollDoc('testcollection', 'test', dbQuery, null, function(err, result) {
             if (err) return done(err);
             expect(result).equal(false);
             done();
diff --git a/test/logger.js b/test/logger.js
index 4efbb0cf..72f75e90 100644
--- a/test/logger.js
+++ b/test/logger.js
@@ -1,5 +1,5 @@
 var Logger = require('../lib/logger/logger');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var sinon = require('sinon');
 
 describe('Logger', function() {
@@ -15,7 +15,7 @@ describe('Logger', function() {
     it('logs to console by default', function() {
       var logger = new Logger();
       logger.warn('warning');
-      expect(console.warn.calledOnceWithExactly('warning')).to.be(true);
+      expect(console.warn.calledOnceWithExactly('warning')).to.equal(true);
     });
 
     it('overrides console', function() {
@@ -27,8 +27,8 @@ describe('Logger', function() {
 
       logger.warn('warning');
 
-      expect(console.warn.notCalled).to.be(true);
-      expect(customWarn.calledOnceWithExactly('warning')).to.be(true);
+      expect(console.warn.notCalled).to.equal(true);
+      expect(customWarn.calledOnceWithExactly('warning')).to.equal(true);
     });
 
     it('only overrides if provided with a method', function() {
@@ -40,7 +40,7 @@ describe('Logger', function() {
 
       logger.warn('warning');
 
-      expect(console.warn.calledOnceWithExactly('warning')).to.be(true);
+      expect(console.warn.calledOnceWithExactly('warning')).to.equal(true);
     });
   });
 });
diff --git a/test/middleware.js b/test/middleware.js
index 0da9f068..9f1ef9f4 100644
--- a/test/middleware.js
+++ b/test/middleware.js
@@ -1,5 +1,5 @@
 var Backend = require('../lib/backend');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var util = require('./util');
 var types = require('../lib/types');
 
@@ -24,6 +24,11 @@ describe('middleware', function() {
       var response = this.backend.use('submit', function() {});
       expect(response).equal(this.backend);
     });
+
+    it('accepts an array of action names', function() {
+      var response = this.backend.use(['submit', 'connect'], function() {});
+      expect(response).equal(this.backend);
+    });
   });
 
   describe('connect', function() {
@@ -208,7 +213,7 @@ describe('middleware', function() {
   });
 
   describe('submit lifecycle', function() {
-    ['submit', 'apply', 'commit', 'afterSubmit'].forEach(function(action) {
+    ['submit', 'apply', 'commit', 'afterWrite'].forEach(function(action) {
       it(action + ' gets options passed to backend.submit', function(done) {
         var doneAfter = util.callAfter(1, done);
         this.backend.use(action, function(request, next) {
@@ -222,4 +227,89 @@ describe('middleware', function() {
       });
     });
   });
+
+  describe('access control', function() {
+    function setupOpMiddleware(backend) {
+      backend.use('apply', function(request, next) {
+        request.priorAccountId = request.snapshot.data && request.snapshot.data.accountId;
+        next();
+      });
+      backend.use('commit', function(request, next) {
+        var accountId = (request.snapshot.data) ?
+          // For created documents, get the accountId from the document data
+          request.snapshot.data.accountId :
+          // For deleted documents, get the accountId from before
+          request.priorAccountId;
+        // Store the accountId for the document on the op for efficient access control
+        request.op.accountId = accountId;
+        next();
+      });
+      backend.use('op', function(request, next) {
+        if (request.op.accountId === request.agent.accountId) {
+          return next();
+        }
+        var err = {message: 'op accountId does not match', code: 'ERR_OP_READ_FORBIDDEN'};
+        return next(err);
+      });
+    }
+
+    it('is possible to cache add additional top-level fields on ops for access control', function(done) {
+      setupOpMiddleware(this.backend);
+      var connection1 = this.backend.connect();
+      var connection2 = this.backend.connect();
+      connection2.agent.accountId = 'foo';
+
+      // Fetching the snapshot here will cause subsequent fetches to get ops
+      connection2.get('dogs', 'fido').fetch(function(err) {
+        if (err) return done(err);
+        var data = {accountId: 'foo', age: 2};
+        connection1.get('dogs', 'fido').create(data, function(err) {
+          if (err) return done(err);
+          // This will go through the 'op' middleware and should pass
+          connection2.get('dogs', 'fido').fetch(done);
+        });
+      });
+    });
+
+    it('op middleware can reject ops', function(done) {
+      setupOpMiddleware(this.backend);
+      var connection1 = this.backend.connect();
+      var connection2 = this.backend.connect();
+      connection2.agent.accountId = 'baz';
+
+      // Fetching the snapshot here will cause subsequent fetches to get ops
+      connection2.get('dogs', 'fido').fetch(function(err) {
+        if (err) return done(err);
+        var data = {accountId: 'foo', age: 2};
+        connection1.get('dogs', 'fido').create(data, function(err) {
+          if (err) return done(err);
+          // This will go through the 'op' middleware and fail;
+          connection2.get('dogs', 'fido').fetch(function(err) {
+            expect(err.code).equal('ERR_OP_READ_FORBIDDEN');
+            done();
+          });
+        });
+      });
+    });
+
+    it('pubsub subscribe can check top-level fields for access control', function(done) {
+      setupOpMiddleware(this.backend);
+      var connection1 = this.backend.connect();
+      var connection2 = this.backend.connect();
+      connection2.agent.accountId = 'foo';
+
+      // Fetching the snapshot here will cause subsequent fetches to get ops
+      connection2.get('dogs', 'fido').subscribe(function(err) {
+        if (err) return done(err);
+        var data = {accountId: 'foo', age: 2};
+        connection1.get('dogs', 'fido').create(data, function(err) {
+          if (err) return done(err);
+          // The subscribed op will go through the 'op' middleware and should pass
+          connection2.get('dogs', 'fido').on('create', function() {
+            done();
+          });
+        });
+      });
+    });
+  });
 });
diff --git a/test/milestone-db.js b/test/milestone-db.js
index 223423d4..b7521636 100644
--- a/test/milestone-db.js
+++ b/test/milestone-db.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var Backend = require('../lib/backend');
 var MilestoneDB = require('../lib/milestone-db');
 var NoOpMilestoneDB = require('../lib/milestone-db/no-op');
@@ -14,14 +14,14 @@ describe('Base class', function() {
 
   it('calls back with an error when trying to get a snapshot', function(done) {
     db.getMilestoneSnapshot('books', '123', 1, function(error) {
-      expect(error.code).to.be(5019);
+      expect(error.code).to.equal(5019);
       done();
     });
   });
 
   it('emits an error when trying to get a snapshot', function(done) {
     db.on('error', function(error) {
-      expect(error.code).to.be(5019);
+      expect(error.code).to.equal(5019);
       done();
     });
 
@@ -30,14 +30,14 @@ describe('Base class', function() {
 
   it('calls back with an error when trying to save a snapshot', function(done) {
     db.saveMilestoneSnapshot('books', {}, function(error) {
-      expect(error.code).to.be(5020);
+      expect(error.code).to.equal(5020);
       done();
     });
   });
 
   it('emits an error when trying to save a snapshot', function(done) {
     db.on('error', function(error) {
-      expect(error.code).to.be(5020);
+      expect(error.code).to.equal(5020);
       done();
     });
 
@@ -46,14 +46,14 @@ describe('Base class', function() {
 
   it('calls back with an error when trying to get a snapshot before a time', function(done) {
     db.getMilestoneSnapshotAtOrBeforeTime('books', '123', 1000, function(error) {
-      expect(error.code).to.be(5021);
+      expect(error.code).to.equal(5021);
       done();
     });
   });
 
   it('calls back with an error when trying to get a snapshot after a time', function(done) {
     db.getMilestoneSnapshotAtOrAfterTime('books', '123', 1000, function(error) {
-      expect(error.code).to.be(5022);
+      expect(error.code).to.equal(5022);
       done();
     });
   });
@@ -83,7 +83,7 @@ describe('NoOpMilestoneDB', function() {
         db.getMilestoneSnapshot('books', 'catcher-in-the-rye', null, next);
       },
       function(snapshot, next) {
-        expect(snapshot).to.be(undefined);
+        expect(snapshot).to.equal(undefined);
         next();
       },
       done
@@ -269,35 +269,35 @@ module.exports = function(options) {
 
     it('errors when fetching an undefined version', function(done) {
       db.getMilestoneSnapshot('books', 'catcher-in-the-rye', undefined, function(error) {
-        expect(error).to.be.ok();
+        expect(error).instanceOf(Error);
         done();
       });
     });
 
     it('errors when fetching version -1', function(done) {
       db.getMilestoneSnapshot('books', 'catcher-in-the-rye', -1, function(error) {
-        expect(error).to.be.ok();
+        expect(error).instanceOf(Error);
         done();
       });
     });
 
     it('errors when fetching version "foo"', function(done) {
       db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 'foo', function(error) {
-        expect(error).to.be.ok();
+        expect(error).instanceOf(Error);
         done();
       });
     });
 
     it('errors when fetching a null collection', function(done) {
       db.getMilestoneSnapshot(null, 'catcher-in-the-rye', 1, function(error) {
-        expect(error).to.be.ok();
+        expect(error).instanceOf(Error);
         done();
       });
     });
 
     it('errors when fetching a null ID', function(done) {
       db.getMilestoneSnapshot('books', null, 1, function(error) {
-        expect(error).to.be.ok();
+        expect(error).instanceOf(Error);
         done();
       });
     });
@@ -312,7 +312,7 @@ module.exports = function(options) {
       );
 
       db.saveMilestoneSnapshot(null, snapshot, function(error) {
-        expect(error).to.be.ok();
+        expect(error).instanceOf(Error);
         done();
       });
     });
@@ -323,7 +323,7 @@ module.exports = function(options) {
           db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 1, next);
         },
         function(snapshot, next) {
-          expect(snapshot).to.be(undefined);
+          expect(snapshot).to.equal(undefined);
           next();
         },
         done
@@ -340,7 +340,7 @@ module.exports = function(options) {
           db.getMilestoneSnapshot('books', 'catcher-in-the-rye', null, next);
         },
         function(snapshot, next) {
-          expect(snapshot).to.be(undefined);
+          expect(snapshot).to.equal(undefined);
           next();
         },
         done
@@ -357,7 +357,7 @@ module.exports = function(options) {
       );
 
       db.on('save', function(collection, snapshot) {
-        expect(collection).to.be('books');
+        expect(collection).to.equal('books');
         expect(snapshot).to.eql(snapshot);
         done();
       });
@@ -367,7 +367,7 @@ module.exports = function(options) {
 
     it('errors when the snapshot is undefined', function(done) {
       db.saveMilestoneSnapshot('books', undefined, function(error) {
-        expect(error).to.be.ok();
+        expect(error).instanceOf(Error);
         done();
       });
     });
@@ -471,14 +471,14 @@ module.exports = function(options) {
 
         it('returns an error for a string timestamp', function(done) {
           db.getMilestoneSnapshotAtOrBeforeTime('books', 'catcher-in-the-rye', 'not-a-timestamp', function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
 
         it('returns an error for a negative timestamp', function(done) {
           db.getMilestoneSnapshotAtOrBeforeTime('books', 'catcher-in-the-rye', -1, function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
@@ -489,7 +489,7 @@ module.exports = function(options) {
               db.getMilestoneSnapshotAtOrBeforeTime('books', 'catcher-in-the-rye', 0, next);
             },
             function(snapshot, next) {
-              expect(snapshot).to.be(undefined);
+              expect(snapshot).to.equal(undefined);
               next();
             },
             done
@@ -498,14 +498,14 @@ module.exports = function(options) {
 
         it('errors if no collection is provided', function(done) {
           db.getMilestoneSnapshotAtOrBeforeTime(undefined, 'catcher-in-the-rye', 0, function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
 
         it('errors if no ID is provided', function(done) {
           db.getMilestoneSnapshotAtOrBeforeTime('books', undefined, 0, function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
@@ -553,14 +553,14 @@ module.exports = function(options) {
 
         it('returns an error for a string timestamp', function(done) {
           db.getMilestoneSnapshotAtOrAfterTime('books', 'catcher-in-the-rye', 'not-a-timestamp', function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
 
         it('returns an error for a negative timestamp', function(done) {
           db.getMilestoneSnapshotAtOrAfterTime('books', 'catcher-in-the-rye', -1, function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
@@ -571,7 +571,7 @@ module.exports = function(options) {
               db.getMilestoneSnapshotAtOrAfterTime('books', 'catcher-in-the-rye', 4000, next);
             },
             function(snapshot, next) {
-              expect(snapshot).to.be(undefined);
+              expect(snapshot).to.equal(undefined);
               next();
             },
             done
@@ -580,14 +580,14 @@ module.exports = function(options) {
 
         it('errors if no collection is provided', function(done) {
           db.getMilestoneSnapshotAtOrAfterTime(undefined, 'catcher-in-the-rye', 0, function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
 
         it('errors if no ID is provided', function(done) {
           db.getMilestoneSnapshotAtOrAfterTime('books', undefined, 0, function(error) {
-            expect(error).to.be.ok();
+            expect(error).instanceOf(Error);
             done();
           });
         });
@@ -608,7 +608,7 @@ module.exports = function(options) {
 
       it('stores a milestone snapshot on commit', function(done) {
         db.on('save', function(collection, snapshot) {
-          expect(collection).to.be('books');
+          expect(collection).to.equal('books');
           expect(snapshot.data).to.eql({title: 'Catcher in the Rye'});
           done();
         });
@@ -639,28 +639,28 @@ module.exports = function(options) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 1, next);
             },
             function(snapshot, next) {
-              expect(snapshot).to.be(undefined);
+              expect(snapshot).to.equal(undefined);
               next();
             },
             function(next) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 2, next);
             },
             function(snapshot, next) {
-              expect(snapshot.v).to.be(2);
+              expect(snapshot.v).to.equal(2);
               next();
             },
             function(next) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 3, next);
             },
             function(snapshot, next) {
-              expect(snapshot.v).to.be(2);
+              expect(snapshot.v).to.equal(2);
               next();
             },
             function(next) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 4, next);
             },
             function(snapshot, next) {
-              expect(snapshot.v).to.be(4);
+              expect(snapshot.v).to.equal(4);
               next();
             },
             done
@@ -699,28 +699,28 @@ module.exports = function(options) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 1, next);
             },
             function(snapshot, next) {
-              expect(snapshot).to.be(undefined);
+              expect(snapshot).to.equal(undefined);
               next();
             },
             function(next) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 2, next);
             },
             function(snapshot, next) {
-              expect(snapshot).to.be(undefined);
+              expect(snapshot).to.equal(undefined);
               next();
             },
             function(next) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 3, next);
             },
             function(snapshot, next) {
-              expect(snapshot.v).to.be(3);
+              expect(snapshot.v).to.equal(3);
               next();
             },
             function(next) {
               db.getMilestoneSnapshot('books', 'catcher-in-the-rye', 4, next);
             },
             function(snapshot, next) {
-              expect(snapshot.v).to.be(4);
+              expect(snapshot.v).to.equal(4);
               next();
             },
             done
diff --git a/test/ot.js b/test/ot.js
index b58b9c89..379d017d 100644
--- a/test/ot.js
+++ b/test/ot.js
@@ -1,33 +1,33 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var ot = require('../lib/ot');
 var type = require('../lib/types').defaultType;
 
 describe('ot', function() {
   describe('checkOp', function() {
     it('fails if op is not an object', function() {
-      expect(ot.checkOp('hi')).ok();
-      expect(ot.checkOp()).ok();
-      expect(ot.checkOp(123)).ok();
-      expect(ot.checkOp([])).ok();
+      expect(ot.checkOp('hi')).ok;
+      expect(ot.checkOp()).ok;
+      expect(ot.checkOp(123)).ok;
+      expect(ot.checkOp([])).ok;
     });
 
     it('fails if op data is missing op, create and del', function() {
-      expect(ot.checkOp({v: 5})).ok();
+      expect(ot.checkOp({v: 5})).ok;
     });
 
     it('fails if src/seq data is invalid', function() {
-      expect(ot.checkOp({del: true, v: 5, src: 'hi'})).ok();
-      expect(ot.checkOp({del: true, v: 5, seq: 123})).ok();
-      expect(ot.checkOp({del: true, v: 5, src: 'hi', seq: 'there'})).ok();
+      expect(ot.checkOp({del: true, v: 5, src: 'hi'})).ok;
+      expect(ot.checkOp({del: true, v: 5, seq: 123})).ok;
+      expect(ot.checkOp({del: true, v: 5, src: 'hi', seq: 'there'})).ok;
     });
 
     it('fails if a create operation is missing its type', function() {
-      expect(ot.checkOp({create: {}})).ok();
-      expect(ot.checkOp({create: 123})).ok();
+      expect(ot.checkOp({create: {}})).ok;
+      expect(ot.checkOp({create: 123})).ok;
     });
 
     it('fails if the type is missing', function() {
-      expect(ot.checkOp({create: {type: 'something that does not exist'}})).ok();
+      expect(ot.checkOp({create: {type: 'something that does not exist'}})).ok;
     });
 
     it('accepts valid create operations', function() {
@@ -54,12 +54,12 @@ describe('ot', function() {
 
   describe('apply', function() {
     it('fails if the versions dont match', function() {
-      expect(ot.apply({v: 0}, {v: 1, create: {type: type.uri}})).ok();
-      expect(ot.apply({v: 0}, {v: 1, del: true})).ok();
-      expect(ot.apply({v: 0}, {v: 1, op: []})).ok();
-      expect(ot.apply({v: 5}, {v: 4, create: {type: type.uri}})).ok();
-      expect(ot.apply({v: 5}, {v: 4, del: true})).ok();
-      expect(ot.apply({v: 5}, {v: 4, op: []})).ok();
+      expect(ot.apply({v: 0}, {v: 1, create: {type: type.uri}})).ok;
+      expect(ot.apply({v: 0}, {v: 1, del: true})).ok;
+      expect(ot.apply({v: 0}, {v: 1, op: []})).ok;
+      expect(ot.apply({v: 5}, {v: 4, create: {type: type.uri}})).ok;
+      expect(ot.apply({v: 5}, {v: 4, del: true})).ok;
+      expect(ot.apply({v: 5}, {v: 4, op: []})).ok;
     });
 
     it('allows the version field to be missing', function() {
@@ -71,7 +71,7 @@ describe('ot', function() {
   describe('create', function() {
     it('fails if the document already exists', function() {
       var doc = {v: 6, create: {type: type.uri}};
-      expect(ot.apply({v: 6, type: type.uri, data: 'hi'}, doc)).ok();
+      expect(ot.apply({v: 6, type: type.uri, data: 'hi'}, doc)).ok;
       // The doc should be unmodified
       expect(doc).eql({v: 6, create: {type: type.uri}});
     });
@@ -105,11 +105,11 @@ describe('ot', function() {
 
   describe('op', function() {
     it('fails if the document does not exist', function() {
-      expect(ot.apply({v: 6}, {v: 6, op: [1, 2, 3]})).ok();
+      expect(ot.apply({v: 6}, {v: 6, op: [1, 2, 3]})).ok;
     });
 
     it('fails if the type is missing', function() {
-      expect(ot.apply({v: 6, type: 'some non existant type'}, {v: 6, op: [1, 2, 3]})).ok();
+      expect(ot.apply({v: 6, type: 'some non existant type'}, {v: 6, op: [1, 2, 3]})).ok;
     });
 
     it('applies the operation to the document data', function() {
@@ -138,21 +138,21 @@ describe('ot', function() {
     it('fails if the version is specified on both and does not match', function() {
       var op1 = {v: 5, op: [{p: [10], si: 'hi'}]};
       var op2 = {v: 6, op: [{p: [5], si: 'abcde'}]};
-      expect(ot.transform(type.uri, op1, op2)).ok();
+      expect(ot.transform(type.uri, op1, op2)).ok;
       expect(op1).eql({v: 5, op: [{p: [10], si: 'hi'}]});
     });
 
     // There's 9 cases here.
     it('create by create fails', function() {
-      expect(ot.transform(null, {v: 10, create: {type: type.uri}}, {v: 10, create: {type: type.uri}})).ok();
+      expect(ot.transform(null, {v: 10, create: {type: type.uri}}, {v: 10, create: {type: type.uri}})).ok;
     });
 
     it('create by delete fails', function() {
-      expect(ot.transform(null, {create: {type: type.uri}}, {del: true})).ok();
+      expect(ot.transform(null, {create: {type: type.uri}}, {del: true})).ok;
     });
 
     it('create by op fails', function() {
-      expect(ot.transform(null, {v: 10, create: {type: type.uri}}, {v: 10, op: [15, 'hi']})).ok();
+      expect(ot.transform(null, {v: 10, create: {type: type.uri}}, {v: 10, op: [15, 'hi']})).ok;
     });
 
     it('create by noop ok', function() {
@@ -162,7 +162,7 @@ describe('ot', function() {
     });
 
     it('delete by create fails', function() {
-      expect(ot.transform(null, {del: true}, {create: {type: type.uri}})).ok();
+      expect(ot.transform(null, {del: true}, {create: {type: type.uri}})).ok;
     });
 
     it('delete by delete ok', function() {
@@ -198,11 +198,11 @@ describe('ot', function() {
     });
 
     it('op by create fails', function() {
-      expect(ot.transform(null, {op: {}}, {create: {type: type.uri}})).ok();
+      expect(ot.transform(null, {op: {}}, {create: {type: type.uri}})).ok;
     });
 
     it('op by delete fails', function() {
-      expect(ot.transform(type.uri, {v: 10, op: []}, {v: 10, del: true})).ok();
+      expect(ot.transform(type.uri, {v: 10, op: []}, {v: 10, del: true})).ok;
     });
 
     it('op by op ok', function() {
diff --git a/test/projections.js b/test/projections.js
index 52dc7261..7bf5eb2a 100644
--- a/test/projections.js
+++ b/test/projections.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 var projections = require('../lib/projections');
 var type = require('../lib/types').defaultType.uri;
 
@@ -12,7 +12,7 @@ describe('projection utility methods', function() {
     it('throws on snapshots with the wrong type', function() {
       expect(function() {
         projections.projectSnapshot({}, {type: 'other', data: 123});
-      }).throwException();
+      }).throw(Error);
     });
 
     it('empty object filters out all properties', function() {
@@ -244,7 +244,7 @@ describe('projection utility methods', function() {
       it('throws on create ops with the wrong type', function() {
         expect(function() {
           projections.projectOp({}, {create: {type: 'other', data: 123}});
-        }).throwException();
+        }).throw(Error);
       });
 
       it('strips data in creates', function() {
diff --git a/test/pubsub-memory.js b/test/pubsub-memory.js
index 498de699..371d982e 100644
--- a/test/pubsub-memory.js
+++ b/test/pubsub-memory.js
@@ -1,6 +1,6 @@
 var MemoryPubSub = require('../lib/pubsub/memory');
 var PubSub = require('../lib/pubsub');
-var expect = require('expect.js');
+var expect = require('chai').expect;
 
 require('./pubsub')(function(callback) {
   callback(null, new MemoryPubSub());
@@ -13,7 +13,7 @@ describe('PubSub base class', function() {
   it('returns an error if _subscribe is unimplemented', function(done) {
     var pubsub = new PubSub();
     pubsub.subscribe('x', function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       expect(err.code).to.equal(5015);
       done();
     });
@@ -22,7 +22,7 @@ describe('PubSub base class', function() {
   it('emits an error if _subscribe is unimplemented and callback is not provided', function(done) {
     var pubsub = new PubSub();
     pubsub.on('error', function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       expect(err.code).to.equal(5015);
       done();
     });
@@ -37,7 +37,7 @@ describe('PubSub base class', function() {
     pubsub.subscribe('x', function(err, stream) {
       if (err) return done(err);
       pubsub.on('error', function(err) {
-        expect(err).to.be.an(Error);
+        expect(err).instanceOf(Error);
         expect(err.code).to.equal(5016);
         done();
       });
@@ -49,7 +49,7 @@ describe('PubSub base class', function() {
     var pubsub = new PubSub();
     pubsub.on('error', done);
     pubsub.publish(['x', 'y'], {test: true}, function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       expect(err.code).to.equal(5017);
       done();
     });
@@ -58,7 +58,7 @@ describe('PubSub base class', function() {
   it('emits an error if _publish is unimplemented and callback is not provided', function(done) {
     var pubsub = new PubSub();
     pubsub.on('error', function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       expect(err.code).to.equal(5017);
       done();
     });
@@ -68,7 +68,7 @@ describe('PubSub base class', function() {
   it('can emit events', function(done) {
     var pubsub = new PubSub();
     pubsub.on('error', function(err) {
-      expect(err).an(Error);
+      expect(err).instanceOf(Error);
       expect(err.message).equal('test error');
       done();
     });
diff --git a/test/pubsub.js b/test/pubsub.js
index 57c19309..123b9496 100644
--- a/test/pubsub.js
+++ b/test/pubsub.js
@@ -1,4 +1,4 @@
-var expect = require('expect.js');
+var expect = require('chai').expect;
 
 module.exports = function(create) {
   describe('pubsub', function() {
@@ -78,7 +78,7 @@ module.exports = function(create) {
 
     it('can emit events', function(done) {
       this.pubsub.on('error', function(err) {
-        expect(err).an(Error);
+        expect(err).instanceOf(Error);
         expect(err.message).equal('test error');
         done();
       });