refactor: Improve error messages in CounterPivotTable and DelimitedList (#27)

Include annotation types and quote field names in error messages for
easier debugging.

Co-authored-by: Rahul Kaushal <kaushalrahul15@gmail.com>

Author: msto

fgmetric/collections/_counter_pivot_table.py

@@ -70,15 +70,15 @@ def _get_counter_fieldname(cls) -> str | None:
         if len(counter_fieldnames) > 1:
             raise TypeError(
                 "Only one Counter per model is currently supported. "
-                f"Found multiple fields with Counter types: {', '.join(counter_fieldnames)}"
+                f"Found multiple Counter fields: {', '.join(counter_fieldnames)}"
             )
 
         counter_fieldname: str | None = counter_fieldnames[0] if counter_fieldnames else None
 
         if counter_fieldname:
             counter_field_info: FieldInfo = cls.model_fields[counter_fieldname]
             if is_optional(counter_field_info.annotation):
-                raise TypeError(f"Optional Counters are not supported: {counter_fieldname}")
+                raise TypeError(f"Optional Counter fields are not supported: '{counter_fieldname}'")
 
         return counter_fieldname
 
@@ -109,7 +109,8 @@ def _get_counter_enum(cls) -> type[StrEnum] | None:  # noqa: C901
             enum_cls: type[StrEnum] = args[0]
         else:
             raise TypeError(
-                f"Counter fields must have a StrEnum type parameter: {cls._counter_fieldname}"
+                f"Counter fields must have a StrEnum type parameter,"
+                f" got {info.annotation} for field '{cls._counter_fieldname}'"
             )
 
         return enum_cls

fgmetric/collections/_delimited_list.py

@@ -101,7 +101,8 @@ def _require_single_character_collection_delimiter(cls) -> None:
         """Require collection delimiters to be single characters."""
         if len(cls.collection_delimiter) != 1:
             raise ValueError(
-                f"Class collection delimiter must be a single character: {cls.collection_delimiter}"
+                "collection_delimiter must be a single character,"
+                f" got: {cls.collection_delimiter!r}"
             )
 
     @final

tests/test_collections.py

@@ -258,7 +258,10 @@ class FakeMetric(Metric):
             name: str
             counts: Counter[str]
 
-    assert str(excinfo.value) == "Counter fields must have a StrEnum type parameter: counts"
+    assert str(excinfo.value) == (
+        "Counter fields must have a StrEnum type parameter,"
+        " got collections.Counter[str] for field 'counts'"
+    )
 
 
 def test_counter_pivot_table_raises_if_multiple_counters() -> None:
@@ -280,7 +283,7 @@ class FakeMetric(Metric):
 
     assert str(excinfo.value) == (
         "Only one Counter per model is currently supported. "
-        "Found multiple fields with Counter types: foo_counts, bar_counts"
+        "Found multiple Counter fields: foo_counts, bar_counts"
     )
 
 
@@ -296,4 +299,4 @@ class FakeMetric(Metric):
             name: str
             counts: Counter[FakeEnum] | None
 
-    assert str(excinfo.value) == "Optional Counters are not supported: counts"
+    assert str(excinfo.value) == "Optional Counter fields are not supported: 'counts'"