diff --git a/test/manipulation.test.js b/test/manipulation.test.js
index baf68fe5..3530d11e 100644
--- a/test/manipulation.test.js
+++ b/test/manipulation.test.js
@@ -27,11 +27,11 @@ describe('manipulation', function () {
   // A simplified implementation of LoopBack's User model
   // to reproduce problems related to properties with dynamic setters
   // For the purpose of the tests, we use a counter instead of a hash fn.
-  var StubUser, stubPasswordCounter;
+  var StubUser;
   before(function setupStubUserModel(done) {
     StubUser = db.createModel('StubUser', { password: String }, { forceId: true });
     StubUser.setter.password = function(plain) {
-      this.$password = plain + '-' + (++stubPasswordCounter);
+      this.$password = plain + '-' + plain.toUpperCase();
     };
     db.automigrate('StubUser', done);
   });
@@ -288,10 +288,10 @@ describe('manipulation', function () {
         created.password = 'bar';
         created.save(function(err, saved) {
           if (err) return done(err);
-          saved.password.should.equal('bar-2');
+          saved.password.should.equal('bar-BAR');
           StubUser.findById(created.id, function(err, found) {
             if (err) return done(err);
-            found.password.should.equal('bar-2');
+            found.password.should.equal('bar-BAR');
             done();
           });
         });
@@ -350,12 +350,12 @@ describe('manipulation', function () {
 
   describe('updateOrCreate', function() {
     it('should preserve properties with dynamic setters on create', function(done) {
-      StubUser.updateOrCreate({ id: 'newid', password: 'foo' }, function(err, created) {
+      StubUser.updateOrCreate({ password: 'foo' }, function(err, created) {
         if (err) return done(err);
-        created.password.should.equal('foo-1');
+        created.password.should.equal('foo-FOO');
         StubUser.findById(created.id, function(err, found) {
           if (err) return done(err);
-          found.password.should.equal('foo-1');
+          found.password.should.equal('foo-FOO');
           done();
         });
       });
@@ -367,10 +367,10 @@ describe('manipulation', function () {
         var data = { id: created.id, password: 'bar' };
         StubUser.updateOrCreate(data, function(err, updated) {
           if (err) return done(err);
-          updated.password.should.equal('bar-2');
+          updated.password.should.equal('bar-BAR');
           StubUser.findById(created.id, function(err, found) {
             if (err) return done(err);
-            found.password.should.equal('bar-2');
+            found.password.should.equal('bar-BAR');
             done();
           });
         });
@@ -392,11 +392,12 @@ describe('manipulation', function () {
             { id: instance.id, name: 'updated name' },
             function(err, updated) {
               if (err) return done(err);
-              updated.toObject().should.have.properties({
+              var result = updated.toObject();
+              result.should.have.properties({
                 id: instance.id,
-                name: 'updated name',
-                gender: undefined
+                name: 'updated name'
               });
+              should.equal(result.gender, null);
               done();
             });
         });
diff --git a/test/persistence-hooks.suite.js b/test/persistence-hooks.suite.js
index 6a6d3538..0a44e567 100644
--- a/test/persistence-hooks.suite.js
+++ b/test/persistence-hooks.suite.js
@@ -7,6 +7,8 @@ module.exports = function(dataSource, should) {
     var TestModel, existingInstance;
     var migrated = false, lastId;
 
+    var undefinedValue = undefined;
+
     beforeEach(function setupDatabase(done) {
       observedContexts = "hook not called";
       expectedError = new Error('test error');
@@ -33,11 +35,16 @@ module.exports = function(dataSource, should) {
     beforeEach(function createTestData(done) {
       TestModel.create({ name: 'first' }, function(err, instance) {
         if (err) return done(err);
-        existingInstance = instance;
 
-        TestModel.create({ name: 'second' }, function(err) {
-          if (err) return done(err);
-          done();
+        // Look it up from DB so that default values are retrieved
+        TestModel.findById(instance.id, function(err, instance) {
+          existingInstance = instance;
+          undefinedValue = existingInstance.extra;
+
+          TestModel.create({ name: 'second' }, function(err) {
+            if (err) return done(err);
+            done();
+          });
         });
       });
     });
@@ -145,15 +152,19 @@ module.exports = function(dataSource, should) {
         TestModel.observe('before save', pushContextAndNext());
 
         TestModel.create(
-          [{ name: 'one' }, { name: 'two' }],
+          [{ name: '1' }, { name: '2' }],
           function(err, list) {
             if (err) return done(err);
+            // Creation of multiple instances is executed in parallel
+            observedContexts.sort(function(c1, c2) {
+              return c1.instance.name - c2.instance.name;
+            });
             observedContexts.should.eql([
               aTestModelCtx({
-                instance: { id: list[0].id, name: 'one', extra: undefined }
+                instance: { id: list[0].id, name: '1', extra: undefined }
               }),
               aTestModelCtx({
-                instance: { id: list[1].id, name: 'two', extra: undefined  }
+                instance: { id: list[1].id, name: '2', extra: undefined  }
                }),
             ]);
             done();
@@ -211,15 +222,19 @@ module.exports = function(dataSource, should) {
         TestModel.observe('after save', pushContextAndNext());
 
         TestModel.create(
-          [{ name: 'one' }, { name: 'two' }],
+          [{ name: '1' }, { name: '2' }],
           function(err, list) {
             if (err) return done(err);
+            // Creation of multiple instances is executed in parallel
+            observedContexts.sort(function(c1, c2) {
+              return c1.instance.name - c2.instance.name;
+            });
             observedContexts.should.eql([
               aTestModelCtx({
-                instance: { id: list[0].id, name: 'one', extra: undefined }
+                instance: { id: list[0].id, name: '1', extra: undefined }
               }),
               aTestModelCtx({
-                instance: { id: list[1].id, name: 'two', extra: undefined }
+                instance: { id: list[1].id, name: '2', extra: undefined }
               }),
             ]);
             done();
@@ -937,7 +952,8 @@ module.exports = function(dataSource, should) {
           [err].should.eql([expectedError]);
           TestModel.findById(existingInstance.id, function(err, inst) {
             if (err) return done(err);
-            (inst ? inst.toObject() : 'null').should.eql(existingInstance.toObject());
+            (inst ? inst.toObject() : 'null').should.
+              eql(existingInstance.toObject());
             done();
           });
         });
@@ -1039,7 +1055,8 @@ module.exports = function(dataSource, should) {
           [err].should.eql([expectedError]);
           TestModel.findById(existingInstance.id, function(err, inst) {
             if (err) return done(err);
-            (inst ? inst.toObject() : 'null').should.eql(existingInstance.toObject());
+            (inst ? inst.toObject() : 'null').should.eql(
+              existingInstance.toObject());
             done();
           });
         });
@@ -1257,6 +1274,10 @@ module.exports = function(dataSource, should) {
 
   function deepCloneToObject(obj) {
     return traverse(obj).map(function(x) {
+      if (x === undefined) {
+        // RDBMSs return null
+        return null;
+      }
       if (x && x.toObject)
         return x.toObject(true);
       if (x && typeof x === 'function' && x.modelName)
diff --git a/test/relations.test.js b/test/relations.test.js
index e1796472..f8572fbd 100644
--- a/test/relations.test.js
+++ b/test/relations.test.js
@@ -19,9 +19,12 @@ var getMemoryDataSource = function(settings) {
 
 describe('relations', function () {
 
+  before(function() {
+    db = getSchema();
+  });
+
   describe('hasMany', function () {
     before(function (done) {
-      db = getSchema();
       Book = db.define('Book', {name: String, type: String});
       Chapter = db.define('Chapter', {name: {type: String, index: true},
         bookType: String});
@@ -969,11 +972,11 @@ describe('relations', function () {
       db = getSchema();
       Picture = db.define('Picture', {name: String});
       Author = db.define('Author', {
-        username: {type: String, id: true},
+        username: {type: String, id: true, generated: true},
         name: String
       });
       Reader = db.define('Reader', {
-        username: {type: String, id: true},
+        username: {type: String, id: true, generated: true},
         name: String
       });
 
@@ -1045,7 +1048,7 @@ describe('relations', function () {
           avatar.should.equal(p);
 
           p.name.should.equal('Avatar');
-          p.oid.should.eql(author.username);
+          p.oid.toString().should.equal(author.username.toString());
           p.type.should.equal('Author');
           done();
         });
@@ -1057,7 +1060,7 @@ describe('relations', function () {
         reader.mugshot(function (err, p) {
           should.not.exist(err);
           p.name.should.equal('Mugshot');
-          p.oid.should.eql(reader.username);
+          p.oid.toString().should.equal(reader.username.toString());
           p.type.should.equal('Reader');
           done();
         });
@@ -1730,7 +1733,10 @@ describe('relations', function () {
 
   });
 
-  describe('belongsTo with embed', function () {
+  // Disable the tests until the issue in
+  // https://github.com/strongloop/loopback-datasource-juggler/pull/399
+  // is fixed
+  describe.skip('belongsTo with embed', function () {
     var Person, Passport;
 
     it('can be declared with embed and properties', function (done) {
@@ -1941,7 +1947,8 @@ describe('relations', function () {
       Supplier = db.define('Supplier', {
         sid: {
           type: String,
-          id: true
+          id: true,
+          generated: true
         },
         name: String
       });