pythoningLearning
diff --git a/‎opc/package.py‎
Lines changed: 10 additions & 0 deletions b/‎opc/package.py‎
Lines changed: 10 additions & 0 deletions
diff --git a/‎tests/test_package.py‎
Lines changed: 20 additions & 1 deletion b/‎tests/test_package.py‎
Lines changed: 20 additions & 1 deletion
@@ -32,11 +32,21 @@ def open(pkg_file):
         return pkg
 
 
+class Part(object):
+    """
+    Base class for package parts. Provides common properties and methods, but
+    intended to be subclassed in client code to implement specific part
+    behaviors.
+    """
+
+
 class PartFactory(object):
     """
     Provides a way for client code to specify a subclass of |Part| to be
     constructed by |Unmarshaller| based on its content type.
     """
+    def __new__(cls, partname, content_type, blob):
+        return Part(partname, content_type, blob)
 
 
 class Unmarshaller(object):
 
@@ -13,7 +13,7 @@
 
 from mock import call, Mock
 
-from opc.package import OpcPackage, Unmarshaller
+from opc.package import OpcPackage, PartFactory, Unmarshaller
 
 from .unitutil import class_mock, method_mock
 
@@ -46,6 +46,25 @@ def it_can_open_a_pkg_file(self, PackageReader_, PartFactory_,
         assert isinstance(pkg, OpcPackage)
 
 
+class DescribePartFactory(object):
+
+    @pytest.fixture
+    def Part_(self, request):
+        return class_mock('opc.package.Part', request)
+
+    def it_constructs_a_part_instance(self, Part_):
+        # mockery ----------------------
+        partname, content_type, blob = (
+            Mock(name='partname'), Mock(name='content_type'),
+            Mock(name='blob')
+        )
+        # exercise ---------------------
+        part = PartFactory(partname, content_type, blob)
+        # verify -----------------------
+        Part_.assert_called_once_with(partname, content_type, blob)
+        assert part == Part_.return_value
+
+
 class DescribeUnmarshaller(object):
 
     @pytest.fixture