MNT: Add useful error message when packet to datasets fails

imap_processing/tests/test_utils.py

@@ -97,6 +97,16 @@ def test_packet_file_to_datasets(use_derived_value, expected_mode):
     np.testing.assert_array_equal(data["mode"], [expected_mode] * len(data["mode"]))
 
 
+def test_packet_file_to_datasets_flat_definition():
+    test_file = "tests/idex/imap_idex_l0_raw_20230725_v001.pkts"
+    packet_files = imap_module_directory / test_file
+    packet_definition = (
+        imap_module_directory / "idex/packet_definitions/idex_packet_definition.xml"
+    )
+    with pytest.raises(ValueError, match="Packet fields do not match"):
+        utils.packet_file_to_datasets(packet_files, packet_definition)
+
+
 def test__create_minimum_dtype_array():
     """Test expected return types for minimum data types."""
     result = utils._create_minimum_dtype_array([1, 2, 3], "uint8")

imap_processing/utils.py

@@ -348,6 +348,8 @@ def packet_file_to_datasets(
     data_dict: dict[int, dict] = dict()
     # Also keep track of the datatype mapping for each field
     datatype_mapping: dict[int, dict] = dict()
+    # Keep track of which variables (keys) are in the dataset
+    variable_mapping: dict[int, set] = dict()
 
     # Set up the parser from the input packet definition
     packet_definition = xtcedef.XtcePacketDefinition(xtce_packet_definition)
@@ -361,6 +363,14 @@ def packet_file_to_datasets(
                 # This is the first packet for this APID
                 data_dict[apid] = collections.defaultdict(list)
                 datatype_mapping[apid] = dict()
+                variable_mapping[apid] = packet.data.keys()
+            if variable_mapping[apid] != packet.data.keys():
+                raise ValueError(
+                    f"Packet fields do not match for APID {apid}. This could be "
+                    f"due to a conditional packet definition in the XTCE, while this "
+                    f"function currently only supports flat packet definitions."
+                    f"\nExpected: {variable_mapping[apid]},\ngot: {packet.data.keys()}"
+                )
 
             # TODO: Do we want to give an option to remove the header content?
             packet_content = packet.data | packet.header