diff --git a/lib/model.js b/lib/model.js
index 7601384..fe3a8f8 100644
--- a/lib/model.js
+++ b/lib/model.js
@@ -66,8 +66,8 @@ function serialize (obj) {
   res = JSON.stringify(obj, function (k, v) {
     checkKey(k, v);
 
+    if (typeof v === undefined) { return null; }
     if (typeof v === 'string' || typeof v === 'number' || typeof v === 'boolean' || v === null) { return v; }
-    //if (v && v.constructor && v.constructor.name === 'Date') { console.log("==============="); return { $$date: v.toString() }; }
 
     return v;
   });
@@ -265,6 +265,24 @@ function areThingsEqual (a, b) {
 }
 
 
+/**
+ * Get a value from object with dot notation
+ * @param {Object} obj
+ * @param {String} field
+ */
+//function getDotValue (obj, field) {
+  //var fieldParts = typeof field === 'string' ? field.split('.') : field;
+
+  //if (!obj) { return false; }   // field cannot be empty here so that means there is no match
+
+  //if (fieldParts.length === 1) {
+    //return obj[fieldParts[0]];
+  //} else {
+    //return matcherFunctions.$eq(obj[fieldParts[0]], fieldParts.slice(1));
+  //}
+//}
+
+
 /**
  * Test for field equality
  * @param {Object} obj The model to check
diff --git a/test/db.test.js b/test/db.test.js
index bcd2712..7350e49 100644
--- a/test/db.test.js
+++ b/test/db.test.js
@@ -284,11 +284,12 @@ describe('Database', function () {
       });
     });
 
-    it.only('By default, matching on an array field is matching any of its components', function (done) {
+    it('By default, matching on an array field is matching any of its components', function (done) {
       d.insert({ fruits: ['orange', 'apple', 'pear'] }, function () {
         d.insert({ fruits: ['banana', 'coconut', 'pear'] }, function () {
           d.find({ fruits: 'pear' }, function (err, docs) {
             console.log(docs);
+            // TODO
             done();
           });
         });
diff --git a/test/model.test.js b/test/model.test.js
index e979b97..2a8c304 100644
--- a/test/model.test.js
+++ b/test/model.test.js
@@ -10,7 +10,7 @@ describe('Model', function () {
 
   describe('Serialization, deserialization', function () {
 
-    it('Can serialize and deserialize strings', function (done) {
+    it('Can serialize and deserialize strings', function () {
       var a, b, c;
 
       a = { test: "Some string" };
@@ -28,11 +28,9 @@ describe('Model', function () {
       a.test.indexOf('\n').should.not.equal(-1);
       b.indexOf('\n').should.equal(-1);
       c.test.indexOf('\n').should.not.equal(-1);
-
-      done();
     });
 
-    it('Can serialize and deserialize booleans', function (done) {
+    it('Can serialize and deserialize booleans', function () {
       var a, b, c;
 
       a = { test: true };
@@ -40,11 +38,9 @@ describe('Model', function () {
       c = model.deserialize(b);
       b.indexOf('\n').should.equal(-1);
       c.test.should.equal(true);
-
-      done();
     });
 
-    it('Can serialize and deserialize numbers', function (done) {
+    it('Can serialize and deserialize numbers', function () {
       var a, b, c;
 
       a = { test: 5 };
@@ -52,11 +48,9 @@ describe('Model', function () {
       c = model.deserialize(b);
       b.indexOf('\n').should.equal(-1);
       c.test.should.equal(5);
-
-      done();
     });
 
-    it('Can serialize and deserialize null', function (done) {
+    it('Can serialize and deserialize null', function () {
       var a, b, c;
 
       a = { test: null };
@@ -64,11 +58,20 @@ describe('Model', function () {
       c = model.deserialize(b);
       b.indexOf('\n').should.equal(-1);
       assert.isNull(a.test);
+    });
 
-      done();
+    it('undefined fields are removed when serialized', function() {
+      var a = { bloup: undefined, hello: 'world' }
+        , b = model.serialize(a)
+        , c = model.deserialize(b)
+        ;
+
+      Object.keys(c).length.should.equal(1);
+      c.hello.should.equal('world');
+      assert.isUndefined(c.bloup);
     });
 
-    it('Can serialize and deserialize a date', function (done) {
+    it('Can serialize and deserialize a date', function () {
       var a, b, c
         , d = new Date();
 
@@ -78,11 +81,9 @@ describe('Model', function () {
       b.indexOf('\n').should.equal(-1);
       c.test.constructor.name.should.equal('Date');
       c.test.getTime().should.equal(d.getTime());
-
-      done();
     });
 
-    it('Can serialize and deserialize sub objects', function (done) {
+    it('Can serialize and deserialize sub objects', function () {
       var a, b, c
         , d = new Date();
 
@@ -93,11 +94,9 @@ describe('Model', function () {
       c.test.something.should.equal(39);
       c.test.also.getTime().should.equal(d.getTime());
       c.test.yes.again.should.equal('yes');
-
-      done();
     });
 
-    it('Can serialize and deserialize sub arrays', function (done) {
+    it('Can serialize and deserialize sub arrays', function () {
       var a, b, c
         , d = new Date();
 
@@ -108,8 +107,6 @@ describe('Model', function () {
       c.test[0].should.equal(39);
       c.test[1].getTime().should.equal(d.getTime());
       c.test[2].again.should.equal('yes');
-
-      done();
     });
 
     it('Reject field names beginning with a $ sign', function (done) {
@@ -328,7 +325,7 @@ describe('Model', function () {
   });   // ==== End of 'Modifying documents' ==== //
 
 
-  describe('Finding documents', function () {
+  describe.only('Finding documents', function () {
 
     describe('Comparing things', function () {