img: add _IfdParser.iter_entries()

Steve Canny · Steve Canny · commit 3d3415e6810d · 2014-02-27T12:08:36.000-08:00
diff --git a/docx/image/tiff.py b/docx/image/tiff.py
@@ -133,7 +133,25 @@ def iter_entries(self):
         Generate an |_IfdEntry| instance corresponding to each entry in the
         directory.
         """
-        raise NotImplementedError
+        for idx in range(self._entry_count):
+            dir_entry_offset = self._offset + 2 + (idx*12)
+            ifd_entry = _IfdEntryFactory(self._stream_rdr, dir_entry_offset)
+            yield ifd_entry
+
+    @property
+    def _entry_count(self):
+        """
+        The count of directory entries, read from the top of the IFD header
+        """
+        return self._stream_rdr.read_short(self._offset)
+
+
+def _IfdEntryFactory(stream_rdr, offset):
+    """
+    Return an |_IfdEntry| subclass instance containing the value of the
+    directory entry at *offset* in *stream_rdr*.
+    """
+    raise NotImplementedError
 
 
 class _IfdEntry(object):
diff --git a/tests/image/test_tiff.py b/tests/image/test_tiff.py
@@ -8,14 +8,16 @@
 
 import pytest
 
+from mock import call
+
 from docx.compat import BytesIO
 from docx.image.helpers import BIG_ENDIAN, LITTLE_ENDIAN, StreamReader
 from docx.image.tiff import (
     _IfdEntries, _IfdEntry, _IfdParser, Tiff, _TiffParser
 )
 
 from ..unitutil import (
-    initializer_mock, class_mock, instance_mock, method_mock
+    function_mock, class_mock, initializer_mock, instance_mock, method_mock
 )
 
 
@@ -207,3 +209,45 @@ def offset_(self, request):
     @pytest.fixture
     def stream_(self, request):
         return instance_mock(request, BytesIO)
+
+
+class Describe_IfdParser(object):
+
+    def it_can_iterate_through_the_directory_entries_in_an_IFD(
+            self, iter_fixture):
+        (ifd_parser, _IfdEntryFactory_, stream_rdr, offsets,
+         expected_entries) = iter_fixture
+        entries = [e for e in ifd_parser.iter_entries()]
+        assert _IfdEntryFactory_.call_args_list == [
+            call(stream_rdr, offsets[0]),
+            call(stream_rdr, offsets[1]),
+        ]
+        assert entries == expected_entries
+
+    # fixtures -------------------------------------------------------
+
+    @pytest.fixture
+    def ifd_entry_(self, request):
+        return instance_mock(request, _IfdEntry, tag=1, value=42)
+
+    @pytest.fixture
+    def ifd_entry_2_(self, request):
+        return instance_mock(request, _IfdEntry, tag=2, value=24)
+
+    @pytest.fixture
+    def _IfdEntryFactory_(self, request, ifd_entry_, ifd_entry_2_):
+        return function_mock(
+            request, 'docx.image.tiff._IfdEntryFactory',
+            side_effect=[ifd_entry_, ifd_entry_2_]
+        )
+
+    @pytest.fixture
+    def iter_fixture(self, _IfdEntryFactory_, ifd_entry_, ifd_entry_2_):
+        stream_rdr = StreamReader(BytesIO(b'\x00\x02'), BIG_ENDIAN)
+        offsets = [2, 14]
+        ifd_parser = _IfdParser(stream_rdr, offset=0)
+        expected_entries = [ifd_entry_, ifd_entry_2_]
+        return (
+            ifd_parser, _IfdEntryFactory_, stream_rdr, offsets,
+            expected_entries
+        )
