img: add _Chunk

Steve Canny · Steve Canny · commit 635131bb8787 · 2014-03-01T01:35:30.000-08:00
diff --git a/docx/image/png.py b/docx/image/png.py
@@ -292,7 +292,14 @@ def from_offset(cls, chunk_type, stream_rdr, offset):
         """
         Return a default _Chunk instance that only knows its chunk type.
         """
-        raise NotImplementedError
+        return cls(chunk_type)
+
+    @property
+    def type_name(self):
+        """
+        The chunk type name, e.g. 'IHDR', 'pHYs', etc.
+        """
+        return self._chunk_type
 
 
 class _IHDRChunk(_Chunk):
diff --git a/tests/image/test_png.py b/tests/image/test_png.py
@@ -506,6 +506,15 @@ def stream_rdr_(self, request):
         return instance_mock(request, StreamReader)
 
 
+class Describe_Chunk(object):
+
+    def it_can_construct_from_a_stream_and_offset(self):
+        chunk_type = 'fOOB'
+        chunk = _Chunk.from_offset(chunk_type, None, None)
+        assert isinstance(chunk, _Chunk)
+        assert chunk.type_name == chunk_type
+
+
 class Describe_IHDRChunk(object):
 
     def it_can_construct_from_a_stream_and_offset(self, from_offset_fixture):
