Add test.

test/test_postprocessor.py

@@ -287,6 +287,15 @@ class MetadataTest(BasePostprocessorTest):
             self._trigger()
         self.assertEqual(self._output(m), "foobar1\nfoobar2\nfoobarbaz\n")
 
+    def test_metadata_tags_array_of_dict(self):
+        self._create(
+            {"mode": "tags"},
+            {"tags": [{"g": "foobar1", "m": "foobar2"}, {"g": None, "m": "foobarbaz"}]},
+        )
+        with patch("builtins.open", mock_open()) as m:
+            self._trigger()
+        self.assertEqual(self._output(m), "foobar1\nfoobar2\nfoobarbaz\n")
+
     def test_metadata_custom(self):
         def test(pp_info):
             pp = self._create(pp_info, {"foo": "bar"})