diff --git a/test/functional/command_write_concern.test.js b/test/functional/command_write_concern.test.js
index 8a614a4f0cd..7f3f5797658 100644
--- a/test/functional/command_write_concern.test.js
+++ b/test/functional/command_write_concern.test.js
@@ -1,1205 +1,213 @@
 'use strict';
-var test = require('./shared').assert;
-var co = require('co');
-var mock = require('mongodb-mock-server');
-
-// Extend the object
-var extend = function(template, fields) {
-  var object = {};
-  for (var name in template) {
-    object[name] = template[name];
-  }
-
-  for (var fieldName in fields) {
-    object[fieldName] = fields[fieldName];
-  }
-
-  return object;
-};
-
-describe('Command Write Concern', function() {
-  afterEach(() => mock.cleanup());
-
-  it('successfully pass through writeConcern to aggregate command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
+const co = require('co');
+const mock = require('mongodb-mock-server');
+const expect = require('chai').expect;
+
+const TEST_OPTIONS = { writeConcern: { w: 2, wtimeout: 1000 } };
+
+class WriteConcernTest {
+  constructor(configuration) {
+    this.configuration = configuration;
+    this.responseDecoration = {};
+    const ObjectId = configuration.require.ObjectId;
+    const electionIds = [new ObjectId(), new ObjectId()];
+    const defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
+      setName: 'rs',
+      setVersion: 1,
+      electionId: electionIds[0],
+      hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
+      primary: 'localhost:32000',
+      arbiters: ['localhost:32002']
+    });
+    this.serverStates = {
+      primary: [
+        Object.assign({}, defaultFields, {
           ismaster: true,
           secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
+          me: 'localhost:32000'
         })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
+      ],
+      firstSecondary: [
+        Object.assign({}, defaultFields, {
           ismaster: false,
           secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
+          me: 'localhost:32001'
         })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
+      ],
+      arbiter: [
+        Object.assign({}, defaultFields, {
           ismaster: false,
           secondary: false,
           arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
+          me: 'localhost:32002'
         })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        let primaryServer = yield mock.createServer(32000, 'localhost');
-        let firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        let arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.aggregate) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
+      ]
+    };
+  }
+  decorateResponse(obj) {
+    Object.assign(this.responseDecoration, obj);
+  }
+  run(resultKey, testFn) {
+    const self = this;
+    co(function*() {
+      let primaryServer = yield mock.createServer(32000, 'localhost');
+      let firstSecondaryServer = yield mock.createServer(32001, 'localhost');
+      let arbiterServer = yield mock.createServer(32002, 'localhost');
+
+      primaryServer.setMessageHandler(request => {
+        const doc = request.document;
+        if (doc.ismaster) {
+          request.reply(self.serverStates.primary[0]);
+        } else if (doc[resultKey]) {
+          self.commandResult = doc;
+          request.reply(Object.assign({ ok: 1 }, self.responseDecoration));
+        } else if (doc.endSessions) {
+          request.reply({ ok: 1 });
+        }
+      });
+
+      firstSecondaryServer.setMessageHandler(request => {
+        const doc = request.document;
+        if (doc.ismaster) {
+          request.reply(self.serverStates.firstSecondary[0]);
+        } else if (doc.endSessions) {
+          request.reply({ ok: 1 });
+        }
+      });
+
+      arbiterServer.setMessageHandler(request => {
+        const doc = request.document;
+        if (doc.ismaster) {
+          request.reply(self.serverStates.arbiter[0]);
+        } else if (doc.endSessions) {
+          request.reply({ ok: 1 });
+        }
+      });
+
+      const client = self.configuration.newClient(
+        'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
+      );
+
+      client.connect(function(err, client) {
+        expect(err).to.not.exist;
+        testFn(client, client.db(self.configuration.db));
+      });
+    });
+  }
+}
+
+function writeConcernTest(command, testFn) {
+  return function(done) {
+    const t = new WriteConcernTest(this.configuration);
+    switch (command) {
+      case 'mapReduce':
+        t.decorateResponse({ result: 'tempCollection' });
+        break;
+    }
+    t.run(command, (client, db) =>
+      testFn.call(this, db, Object.assign({}, TEST_OPTIONS), err => {
+        expect(err).to.not.exist;
+        expect(TEST_OPTIONS.writeConcern).to.deep.equal(t.commandResult.writeConcern);
+        client.close(done);
+      })
+    );
+  };
+}
 
-          db.collection('test')
-            .aggregate([{ $match: {} }, { $out: 'readConcernCollectionAggregate1Output' }], {
-              w: 2,
-              wtimeout: 1000
-            })
-            .toArray(function(err) {
-              test.equal(null, err);
-              test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
+describe('Command Write Concern', function() {
+  afterEach(() => mock.cleanup());
+  const metadata = { requires: { generators: true, topology: 'single' } };
 
-              client.close(done);
-            });
-        });
-      });
-    }
+  it('successfully pass through writeConcern to aggregate command', {
+    metadata,
+    test: writeConcernTest('aggregate', function(db, writeConcernTestOptions, done) {
+      db.collection('test')
+        .aggregate(
+          [{ $match: {} }, { $out: 'readConcernCollectionAggregate1Output' }],
+          writeConcernTestOptions
+        )
+        .toArray(done);
+    })
   });
 
   it('successfully pass through writeConcern to create command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId,
-        Long = configuration.require.Long;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.listCollections) {
-            request.reply({
-              ok: 1,
-              cursor: {
-                id: Long.fromNumber(0),
-                ns: 'test.cmd$.listCollections',
-                firstBatch: []
-              }
-            });
-          } else if (doc.create) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          db.createCollection('test_collection_methods', { w: 2, wtimeout: 1000 }, function(err) {
-            test.equal(null, err);
-            test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-            client.close(done);
-          });
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('create', function(db, writeConcernTestOptions, done) {
+      db.createCollection('test_collection_methods', writeConcernTestOptions, done);
+    })
   });
 
   it('successfully pass through writeConcern to createIndexes command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.createIndexes) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          db.collection('indexOptionDefault').createIndex(
-            { a: 1 },
-            {
-              indexOptionDefaults: true,
-              w: 2,
-              wtimeout: 1000
-            },
-            function(err) {
-              test.equal(null, err);
-              test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-              client.close(done);
-            }
-          );
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('createIndexes', function(db, writeConcernTestOptions, done) {
+      db.collection('indexOptionDefault').createIndex(
+        { a: 1 },
+        Object.assign({ indexOptionDefaults: true }, writeConcernTestOptions),
+        done
+      );
+    })
   });
 
   it('successfully pass through writeConcern to drop command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.drop) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          db.collection('indexOptionDefault').drop(
-            {
-              w: 2,
-              wtimeout: 1000
-            },
-            function(err) {
-              test.equal(null, err);
-              test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-              client.close(done);
-            }
-          );
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('drop', function(db, writeConcernTestOptions, done) {
+      db.collection('indexOptionDefault').drop(writeConcernTestOptions, done);
+    })
   });
 
   it('successfully pass through writeConcern to dropDatabase command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.dropDatabase) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          db.dropDatabase(
-            {
-              w: 2,
-              wtimeout: 1000
-            },
-            function(err) {
-              test.equal(null, err);
-              test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-              client.close(done);
-            }
-          );
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('dropDatabase', function(db, writeConcernTestOptions, done) {
+      db.dropDatabase(writeConcernTestOptions, done);
+    })
   });
 
   it('successfully pass through writeConcern to dropIndexes command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.dropIndexes) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          db.collection('test').dropIndexes(
-            {
-              w: 2,
-              wtimeout: 1000
-            },
-            function(err) {
-              test.equal(null, err);
-              test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-              client.close(done);
-            }
-          );
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('dropIndexes', function(db, writeConcernTestOptions, done) {
+      db.collection('test').dropIndexes(writeConcernTestOptions, done);
+    })
   });
 
   it('successfully pass through writeConcern to mapReduce command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId,
-        Code = configuration.require.Code;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.mapReduce) {
-            commandResult = doc;
-            request.reply({ ok: 1, result: 'tempCollection' });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          // String functions
-          var map = new Code('function() { emit(this.user_id, 1); }');
-          var reduce = new Code('function(k,vals) { return 1; }');
-
-          // db.collection('test').mapReduce({
-          db.collection('test').mapReduce(
-            map,
-            reduce,
-            {
-              out: { replace: 'tempCollection' },
-              w: 2,
-              wtimeout: 1000
-            },
-            function(err) {
-              test.equal(null, err);
-              test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-              client.close(done);
-            }
-          );
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('mapReduce', function(db, writeConcernTestOptions, done) {
+      const Code = this.configuration.require.Code;
+      const map = new Code('function() { emit(this.user_id, 1); }');
+      const reduce = new Code('function(k,vals) { return 1; }');
+      db.collection('test').mapReduce(
+        map,
+        reduce,
+        Object.assign({ out: { replace: 'tempCollection' } }, writeConcernTestOptions),
+        done
+      );
+    })
   });
 
   it('successfully pass through writeConcern to createUser command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.createUser) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          db.admin().addUser('kay:kay', 'abc123', { w: 2, wtimeout: 1000 }, function(err) {
-            test.equal(null, err);
-            test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-            client.close(done);
-          });
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('createUser', function(db, writeConcernTestOptions, done) {
+      db.admin().addUser('kay:kay', 'abc123', writeConcernTestOptions, done);
+    })
   });
 
   it('successfully pass through writeConcern to dropUser command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.dropUser) {
-            commandResult = doc;
-            request.reply({ ok: 1 });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          db.admin().removeUser('kay:kay', { w: 2, wtimeout: 1000 }, function(err) {
-            test.equal(null, err);
-            test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-            client.close(done);
-          });
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('dropUser', function(db, writeConcernTestOptions, done) {
+      db.admin().removeUser('kay:kay', writeConcernTestOptions, done);
+    })
   });
 
   it('successfully pass through writeConcern to findAndModify command', {
-    metadata: {
-      requires: {
-        generators: true,
-        topology: 'single'
-      }
-    },
-
-    test: function(done) {
-      var configuration = this.configuration,
-        ObjectId = configuration.require.ObjectId;
-
-      var electionIds = [new ObjectId(), new ObjectId()];
-      var defaultFields = Object.assign({}, mock.DEFAULT_ISMASTER, {
-        setName: 'rs',
-        setVersion: 1,
-        electionId: electionIds[0],
-        hosts: ['localhost:32000', 'localhost:32001', 'localhost:32002'],
-        arbiters: ['localhost:32002']
-      });
-
-      // Primary server states
-      var primary = [
-        extend(defaultFields, {
-          ismaster: true,
-          secondary: false,
-          me: 'localhost:32000',
-          primary: 'localhost:32000',
-          tags: { loc: 'ny' }
-        })
-      ];
-
-      // Primary server states
-      var firstSecondary = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: true,
-          me: 'localhost:32001',
-          primary: 'localhost:32000',
-          tags: { loc: 'sf' }
-        })
-      ];
-
-      // Primary server states
-      var arbiter = [
-        extend(defaultFields, {
-          ismaster: false,
-          secondary: false,
-          arbiterOnly: true,
-          me: 'localhost:32002',
-          primary: 'localhost:32000'
-        })
-      ];
-
-      // Boot the mock
-      co(function*() {
-        const primaryServer = yield mock.createServer(32000, 'localhost');
-        const firstSecondaryServer = yield mock.createServer(32001, 'localhost');
-        const arbiterServer = yield mock.createServer(32002, 'localhost');
-
-        primaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(primary[0]);
-          } else if (doc.findAndModify) {
-            commandResult = doc;
-            request.reply({ ok: 1, result: {} });
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        firstSecondaryServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(firstSecondary[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        arbiterServer.setMessageHandler(request => {
-          var doc = request.document;
-          if (doc.ismaster) {
-            request.reply(arbiter[0]);
-          } else if (doc.endSessions) {
-            request.reply({ ok: 1 });
-          }
-        });
-
-        var commandResult = null;
-
-        // Connect to the mocks
-        const client = configuration.newClient(
-          'mongodb://localhost:32000,localhost:32001,localhost:32002/test?replicaSet=rs'
-        );
-
-        client.connect(function(err, client) {
-          test.equal(null, err);
-          var db = client.db(configuration.db);
-
-          // Simple findAndModify command returning the new document
-          db.collection('test').findAndModify(
-            { a: 1 },
-            [['a', 1]],
-            { $set: { b1: 1 } },
-            { new: true, w: 2, wtimeout: 1000 },
-            function(err) {
-              test.equal(null, err);
-              test.deepEqual({ w: 2, wtimeout: 1000 }, commandResult.writeConcern);
-
-              client.close(done);
-            }
-          );
-        });
-      });
-    }
+    metadata,
+    test: writeConcernTest('findAndModify', function(db, writeConcernTestOptions, done) {
+      db.collection('test').findAndModify(
+        { a: 1 },
+        [['a', 1]],
+        { $set: { b1: 1 } },
+        Object.assign({ new: true }, writeConcernTestOptions),
+        done
+      );
+    })
   });
 });