metadata writer: some progress

test/test_metadata_writer.py

@@ -0,0 +1,8 @@
+
+from photools3.metadata_writer import read_metadata
+from test.test_photo import PATHS_DNG_EXAMPLES
+
+
+def test_read_metadata():
+    result = read_metadata(PATHS_DNG_EXAMPLES[0])
+    assert result