Adjust the api to use node-style callbacks with error parameter.

lib/persistence/plain.js

@@ -1,22 +1,21 @@
 var fs = require('fs');
 var defer = process.nextTick;
 
+
 exports.connect = function connect(filename, callback) {
   defer(function () {
-    callback({
+    callback(null, {
       getStore: function getStore(name, callback) {
         defer(function () {
-          callback({
+          callback(null, {
             get: function get(query, options, callback) {},
             insert: function insert(data, callback) {},
             update: function update(data, query, options, callback) {},
             remove: function remove(query, options, callback) {}
           });
         })
       },
-      close: function (callback) {
-        defer(callback);
-      }
+      close: defer
     });
   });
 };

test.js

@@ -9,12 +9,14 @@ Step(
     sys.puts("connect");
     DbDriver.connect('mydb.json', this);
   },
-  function getStore(db) {
-    sys.puts("getStore");
+  function getStore(err, db) {
+    if (err) { throw err; }
+    sys.puts("getStore", sys.inspect(db));
     this.db = db;
     db.getStore("people", this);
   },
-  function testStore(people) {
+  function testStore(err, people) {
+    if (err) { throw err; }
     people.get();
     people.update();
     people.insert();
@@ -23,7 +25,8 @@ Step(
     sys.p(people);
     this.db.close(this);
   },
-  function done() {
+  function done(err) {
+    if (err) { throw err; }
     sys.puts("done");
   }
 );