img: add _MarkerFinder.from_stream()

Steve Canny · Steve Canny · commit 2b14ad4e8102 · 2014-02-27T12:08:35.000-08:00
diff --git a/docx/image/jpeg.py b/docx/image/jpeg.py
@@ -139,12 +139,16 @@ class _MarkerFinder(object):
     """
     Service class that knows how to find the next JFIF marker in a stream.
     """
+    def __init__(self, stream):
+        super(_MarkerFinder, self).__init__()
+        self._stream = stream
+
     @classmethod
     def from_stream(cls, stream):
         """
         Return a |_MarkerFinder| instance to find JFIF markers in *stream*.
         """
-        raise NotImplementedError
+        return cls(stream)
 
     def next(self, start):
         """
diff --git a/tests/image/test_jpeg.py b/tests/image/test_jpeg.py
@@ -151,6 +151,29 @@ def stream_(self, request):
         return instance_mock(request, BytesIO)
 
 
+class Describe_MarkerFinder(object):
+
+    def it_can_construct_from_a_stream(self, from_stream_fixture):
+        stream_, _MarkerFinder__init_ = from_stream_fixture
+        marker_finder = _MarkerFinder.from_stream(stream_)
+        _MarkerFinder__init_.assert_called_once_with(stream_)
+        assert isinstance(marker_finder, _MarkerFinder)
+
+    # fixtures -------------------------------------------------------
+
+    @pytest.fixture
+    def from_stream_fixture(self, stream_, _MarkerFinder__init_):
+        return stream_, _MarkerFinder__init_
+
+    @pytest.fixture
+    def _MarkerFinder__init_(self, request):
+        return initializer_mock(request, _MarkerFinder)
+
+    @pytest.fixture
+    def stream_(self, request):
+        return instance_mock(request, BytesIO)
+
+
 class Describe_MarkerParser(object):
 
     def it_can_construct_from_a_jfif_stream(self, from_stream_fixture):
