Add test for reading JSON with missing group_counter_start entry

This tests that the fallback constructor code triggers
correctly.

tests/data/fitsheader-hsc.json

@@ -0,0 +1 @@
+{"_translator": "HSC", "telescope": "Subaru", "instrument": "HSC", "location": [-5464492.282102364, -2493000.6266314997, 2150943.6513960036], "exposure_id": 904024, "visit_id": 904024, "physical_filter": "HSC-I", "datetime_begin": [2456599.0, -0.23853115740740743], "datetime_end": [2456599.0, -0.23816055555555554], "exposure_time": 30.0, "dark_time": 30.0, "boresight_airmass": 1.121626027604189, "boresight_rotation_angle": 270.0, "boresight_rotation_coord": "sky", "detector_num": 50, "detector_name": "12", "detector_unique_name": "1_12", "detector_serial": "120", "detector_group": "1", "detector_exposure_id": 180804850, "object": "STRIPE82L", "temperature": 272.35, "pressure": 621.7, "relative_humidity": 33.1, "tracking_radec": [320.74992499999996, 0.5000194444444445], "altaz_begin": [226.68922661, 63.04359233], "science_program": "o13015", "observation_type": "science", "observation_id": "HSCA90402400", "observation_reason": "science", "exposure_group": "904024", "observing_day": 20131102, "observation_counter": 904024, "group_counter_end": 904024, "__CONTENT__": "translated"}

tests/test_indexing.py

@@ -184,6 +184,21 @@ def test_file_reading(self):
         with self.assertRaises(ValueError):
             read_index(bad_file)
 
+    def test_obs_info_sidecar(self):
+        """Test reading of older files with missing content."""
+
+        # First with a real header (but YAML)
+        file = os.path.join(TESTDATA, "fitsheader-hsc.yaml")
+        info = read_file_info(file, 1, None, "translated", content_type="native")
+        self.assertIsInstance(info, ObservationInfo)
+        self.assertEqual(info.instrument, "HSC")
+
+        # With translated metadata sidecar that lacks the group_counter_start.
+        json_file = os.path.splitext(file)[0] + ".json"
+        json_info = read_sidecar(json_file)
+        self.assertIsInstance(json_info, ObservationInfo)
+        self.assertEqual(json_info, info)
+
 
 if __name__ == "__main__":
     unittest.main()