Mod: Show regressions in shape colouring

This PR demonstrates the known regressions of the recently merged material branch:
* Changing the transparency after setting color per face will reset them
* The result of boolean operations or compound doesn't inherit the colour of its input objects
* If colour is set per face to a boolean operaton object then saving and restoring the file causes weird rendering behaviour
  because material binding is set to PER_PART but only a single colour is defined
* If a shape inside a part container has set colour per face then saving and restoring as STEP file causes weird rendering
behaviour for the same reason
* Shape binder or datum objects don't show the correct default shape colour

src/Mod/PartDesign/TestPartDesignGui.py

@@ -253,3 +253,87 @@ class PartDesignTransformed(unittest.TestCase):
 #   def tearDown(self):
 #       #closing doc
 #       FreeCAD.closeDocument("SketchGuiTest")
+
+class TestShapeBinder(unittest.TestCase):
+    def setUp(self):
+        self.Doc = FreeCAD.newDocument("PartDesignTestShapeBinder")
+
+    def testDefaultColor(self):
+        """
+        A shape binder uses a different default color than a Part feature.
+        This color must still be set after its creation.
+        """
+        self.Body = self.Doc.addObject('PartDesign::Body','Body')
+        self.Box = self.Doc.addObject('PartDesign::AdditiveBox','Box')
+        self.Body.addObject(self.Box)
+        self.Doc.recompute()
+        binder = self.Doc.addObject('PartDesign::ShapeBinder','ShapeBinder')
+        binder.Support = [(self.Box, 'Face1')]
+
+        grp = App.ParamGet("User parameter:BaseApp/Preferences/Mod/PartDesign")
+        packed_color = grp.GetUnsigned("DefaultDatumColor", 0xFFD70099)
+        r, g, b, a = binder.ViewObject.ShapeColor
+        color = int(r * 255.0 + 0.5) << 24 | int(g * 255.0 + 0.5) << 16 | int(b * 255.0 + 0.5) << 8 | int(a * 255.0 + 0.5)
+
+        self.assertEqual(packed_color, color)
+
+    def tearDown(self):
+        FreeCAD.closeDocument(self.Doc.Name)
+
+
+class TestSubShapeBinder(unittest.TestCase):
+    def setUp(self):
+        self.Doc = FreeCAD.newDocument("PartDesignTestSubShapeBinder")
+
+    def tearDown(self):
+        FreeCAD.closeDocument(self.Doc.Name)
+
+    def testDefaultColor(self):
+        """
+        A sub-shape binder uses a different default color than a Part feature.
+        This color must still be set after its creation.
+        """
+        body = self.Doc.addObject('PartDesign::Body','Body')
+        box = self.Doc.addObject('PartDesign::AdditiveBox','Box')
+        body.addObject(box)
+
+        self.Doc.recompute()
+        binder = body.newObject('PartDesign::SubShapeBinder','Binder')
+        binder.Support = [(box, ("Face1"))]
+
+        grp = App.ParamGet("User parameter:BaseApp/Preferences/Mod/PartDesign")
+        packed_color = grp.GetUnsigned("DefaultDatumColor", 0xFFD70099)
+        r, g, b, a = binder.ViewObject.ShapeColor
+        color = int(r * 255.0 + 0.5) << 24 | int(g * 255.0 + 0.5) << 16 | int(b * 255.0 + 0.5) << 8 | int(a * 255.0 + 0.5)
+
+        self.assertEqual(packed_color, color)
+
+
+class TestDatumPlane(unittest.TestCase):
+    def setUp(self):
+        self.Doc = FreeCAD.newDocument("PartDesignTestDatumPlane")
+
+    def tearDown(self):
+        FreeCAD.closeDocument(self.Doc.Name)
+
+    def testDefaultColor(self):
+        """
+        A datum object uses a different default color than a Part feature.
+        This color must still be set after its creation.
+        """
+        body = self.Doc.addObject('PartDesign::Body','Body')
+        box = self.Doc.addObject('PartDesign::AdditiveBox','Box')
+        body.addObject(box)
+
+        self.Doc.recompute()
+        datum = body.newObject('PartDesign::Plane','DatumPlane')
+        datum.AttachmentSupport = [(box, 'Face6')]
+        datum.MapMode = 'FlatFace'
+        self.Doc.recompute()
+
+        grp = App.ParamGet("User parameter:BaseApp/Preferences/Mod/PartDesign")
+        packed_color = grp.GetUnsigned("DefaultDatumColor", 0xFFD70099)
+        r, g, b, a = datum.ViewObject.ShapeColor
+        color = int(r * 255.0 + 0.5) << 24 | int(g * 255.0 + 0.5) << 16 | int(b * 255.0 + 0.5) << 8 | int(a * 255.0 + 0.5)
+
+        self.assertEqual(packed_color, color)