diff --git a/python/core/qgsmapthemecollection.sip b/python/core/qgsmapthemecollection.sip
index a6b5c61bfc1..94ee5370393 100644
--- a/python/core/qgsmapthemecollection.sip
+++ b/python/core/qgsmapthemecollection.sip
@@ -150,11 +150,13 @@ class QgsMapThemeCollection : QObject
      * @note added in QGIS 3.0
      */
     void applyTheme( const QString& name, QgsLayerTreeGroup* root, QgsLayerTreeModel* model );
-
+    QgsProject* project();
+    void setProject( QgsProject* project );
   signals:
 
     /** Emitted when map themes within the collection are changed.
      */
     void mapThemesChanged();
+    void projectChanged();
 };
 
diff --git a/python/core/qgsprojectversion.sip b/python/core/qgsprojectversion.sip
index a74f3b6e7d2..6f96af33137 100644
--- a/python/core/qgsprojectversion.sip
+++ b/python/core/qgsprojectversion.sip
@@ -20,6 +20,7 @@ class QgsProjectVersion
     int minorVersion();
     int subVersion();
     QString text();
+    bool isNull() const;
 
     /** Boolean equal operator
      */
diff --git a/python/core/qgssnappingconfig.sip b/python/core/qgssnappingconfig.sip
index 4554f0fc5d8..9daf14ccda0 100644
--- a/python/core/qgssnappingconfig.sip
+++ b/python/core/qgssnappingconfig.sip
@@ -222,6 +222,6 @@ class QgsSnappingConfig
      */
     bool removeLayers( const QList<QgsMapLayer*>& layers );
     QgsProject* project() const;
-    void setProject(QgsProject* project);
+    void setProject( QgsProject* project );
 
 };
diff --git a/src/core/qgssnappingconfig.h b/src/core/qgssnappingconfig.h
index 45b43a08313..6cc89f9ab2d 100644
--- a/src/core/qgssnappingconfig.h
+++ b/src/core/qgssnappingconfig.h
@@ -227,7 +227,7 @@ class CORE_EXPORT QgsSnappingConfig
     QgsProject* project() const;
 
     /**
-     * \copydoc project()
+     * The project from which the snapped layers should be retrieved
      *
      * \note Added in QGIS 3.0
      */
diff --git a/tests/src/python/test_qgsattributetablemodel.py b/tests/src/python/test_qgsattributetablemodel.py
index f5e75d470e0..0fdebe23bf5 100644
--- a/tests/src/python/test_qgsattributetablemodel.py
+++ b/tests/src/python/test_qgsattributetablemodel.py
@@ -42,7 +42,6 @@ class TestQgsAttributeTableModel(unittest.TestCase):
         self.cache = QgsVectorLayerCache(self.layer, 100)
         self.am = QgsAttributeTableModel(self.cache)
         self.am.loadLayer()
-        self.am.loadAttributes()
 
     def tearDown(self):
         del self.am
diff --git a/tests/src/python/test_qgsfieldformatters.py b/tests/src/python/test_qgsfieldformatters.py
index 422f6753780..df0a5ee2fc2 100644
--- a/tests/src/python/test_qgsfieldformatters.py
+++ b/tests/src/python/test_qgsfieldformatters.py
@@ -14,7 +14,7 @@ __revision__ = '$Format:%H$'
 
 import qgis  # NOQA
 
-from qgis.core import (QgsMapLayerRegistry, QgsFeature, QgsGeometry, QgsPoint,
+from qgis.core import (QgsFeature, QgsGeometry, QgsPoint,
                        QgsProject, QgsRelation, QgsVectorLayer, NULL, QgsField,
                        QgsValueMapFieldFormatter, QgsValueRelationFieldFormatter,
                        QgsRelationReferenceFieldFormatter)
@@ -34,7 +34,7 @@ class TestQgsValueMapFieldFormatter(unittest.TestCase):
         layer = QgsVectorLayer("none?field=number1:integer&field=number2:double&field=text1:string&field=number3:integer&field=number4:double&field=text2:string",
                                "layer", "memory")
         self.assertTrue(layer.isValid())
-        QgsMapLayerRegistry.instance().addMapLayer(layer)
+        QgsProject.instance().addMapLayer(layer)
         f = QgsFeature()
         f.setAttributes([2, 2.5, 'NULL', None, None, None])
         layer.dataProvider().addFeatures([f])
@@ -60,7 +60,7 @@ class TestQgsValueMapFieldFormatter(unittest.TestCase):
         self.assertEqual(fieldFormatter.representValue(layer, 4, config, None, None), '(NULL)')
         self.assertEqual(fieldFormatter.representValue(layer, 5, config, None, None), '(NULL)')
 
-        QgsMapLayerRegistry.instance().removeAllMapLayers()
+        QgsProject.instance().removeAllMapLayers()
 
 
 class TestQgsValueRelationFieldFormatter(unittest.TestCase):
@@ -73,7 +73,7 @@ class TestQgsValueRelationFieldFormatter(unittest.TestCase):
         second_layer = QgsVectorLayer("none?field=pkid:integer&field=decoded:string",
                                       "second_layer", "memory")
         self.assertTrue(second_layer.isValid())
-        QgsMapLayerRegistry.instance().addMapLayer(second_layer)
+        QgsProject.instance().addMapLayer(second_layer)
         f = QgsFeature()
         f.setAttributes([123])
         first_layer.dataProvider().addFeatures([f])
@@ -107,7 +107,7 @@ class TestQgsValueRelationFieldFormatter(unittest.TestCase):
         config = {'Layer': second_layer.id(), 'Key': 'pkid', 'Value': 'invalid'}
         self.assertEqual(fieldFormatter.representValue(first_layer, 0, config, None, '456'), '(456)')
 
-        QgsMapLayerRegistry.instance().removeMapLayer(second_layer.id())
+        QgsProject.instance().removeMapLayer(second_layer.id())
 
 
 class TestQgsRelationReferenceFieldFormatter(unittest.TestCase):
@@ -120,7 +120,7 @@ class TestQgsRelationReferenceFieldFormatter(unittest.TestCase):
         second_layer = QgsVectorLayer("none?field=pkid:integer&field=decoded:string",
                                       "second_layer", "memory")
         self.assertTrue(second_layer.isValid())
-        QgsMapLayerRegistry.instance().addMapLayers([first_layer, second_layer])
+        QgsProject.instance().addMapLayers([first_layer, second_layer])
         f = QgsFeature()
         f.setAttributes([123])
         first_layer.dataProvider().addFeatures([f])
@@ -196,7 +196,7 @@ class TestQgsRelationReferenceFieldFormatter(unittest.TestCase):
         second_layer.setDisplayExpression('decoded')
         self.assertEqual(fieldFormatter.representValue(first_layer, 0, config, None, '123'), '123')
 
-        QgsMapLayerRegistry.instance().removeAllMapLayers()
+        QgsProject.instance().removeAllMapLayers()
 
 if __name__ == '__main__':
     unittest.main()
diff --git a/tests/testdata/provider/testdata_pg.sql b/tests/testdata/provider/testdata_pg.sql
index 62d5a8a3823..705a3d406c4 100644
--- a/tests/testdata/provider/testdata_pg.sql
+++ b/tests/testdata/provider/testdata_pg.sql
@@ -457,7 +457,7 @@ CREATE TABLE qgis_test.widget_styles(
 );
 
 INSERT INTO qgis_editor_widget_styles VALUES
-('qgis_test', 'widget_styles', 'fld1', 'FooEdit', '<config type="Map"><Option name="param1" value="value1" type="String"/><Option name="param2" value="2" type="String"/></config>');
+('qgis_test', 'widget_styles', 'fld1', 'FooEdit', '<config type="Map"><Option name="param1" value="value1" type="QString"/><Option name="param2" value="2" type="QString"/></config>');
 
 
 -----------------------------