fix(bigquery): account for range element type, rounding mode, and foreign type in SchemaField equality

[chalmerlowe]

Problem

When comparing two SchemaField objects with ==, fields with different range_element_type values (such as RANGE versus RANGE) were incorrectly evaluated as equal (True).

Investigation revealed that SchemaField._key() omitted range_element_type, meaning two fields with different range element types produced identical comparison keys. Furthermore, rounding_mode and foreign_type_definition were also omitted from _key(), causing fields differing only in those attributes to compare as equal. In addition, FieldElementType lacked custom equality (__eq__) and hashing (__hash__) methods, which prevented comparing element types directly.

Solution

1. SchemaField._key:
   • Parameterized RANGE fields as RANGE in _key(), following the existing conventions used for STRING(max_length) and NUMERIC(precision, scale).
   • Added rounding_mode and foreign_type_definition to _key().
2. SchemaField.__repr__:
   • Updated representation unpacking to cleanly handle all key attributes.
3. FieldElementType:
   • Implemented _key, __eq__, __ne__, __hash__, and __repr__ for FieldElementType.
4. Unit test coverage:
   • Added mismatch and match tests for range_element_type, rounding_mode, and foreign_type_definition.
   • Added equality, hash, and representation tests for FieldElementType.
   • Added parameterized tests verifying SchemaField.from_api_repr generates expected _key() values for RANGE types.

Notes to Reviewers

• Parameterizing RANGE as RANGE aligns with GoogleSQL syntax and mirrors how parameterized string, bytes, and numeric fields are handled in SchemaField._key().
• FieldElementType comparisons are case-insensitive because element types are normalized to uppercase upon creation.

[gemini-code-assist]

Code Review

This pull request updates the BigQuery schema classes to support new fields, including RANGE element types, rounding_mode, and foreign_type_definition. Specifically, it implements equality, hashing, and representation methods for FieldElementType, and updates SchemaField._key() and SchemaField.__repr__ to include these new attributes, along with adding comprehensive unit tests. Feedback on the changes suggests simplifying the SchemaField.__repr__ implementation by slicing the key tuple instead of unpacking all ten attributes to prevent fragility, and avoiding the local import of FieldElementType inside a test function since the schema module is already imported at the module level.

[gemini-code-assist]

The current implementation of __repr__ explicitly unpacks and reconstructs all 10 attributes of SchemaField. This is highly verbose and fragile, as any future addition or reordering of fields in _key() will break this method. Since only policy_tags needs to be modified for the representation, we can slice the key tuple and replace the policy_tags element by index, making the code much more concise and maintainable.

        key = self._key()
        policy_tags = key[6]
        policy_tags_inst = None if policy_tags is None else PolicyTagList(policy_tags)
        adjusted_key = key[:6] + (policy_tags_inst,) + key[7:]
        return f"{self.__class__.__name__}{adjusted_key}"

[chalmerlowe]

Addressed by introducing an internal _SchemaFieldKey NamedTuple and using key._replace(policy_tags=...) in __repr__. This avoids both verbose explicit unpacking and brittle magic index slicing (key[:6]), ensuring future field additions or reorderings remain safe.

[gemini-code-assist]

Avoid importing FieldElementType inside the test function since the schema module is already imported at the module level. You can reference it directly as schema.FieldElementType.

        field = self._make_one("R", "RANGE", range_element_type="DATE")
        other = self._make_one(
            "R", "RANGE", range_element_type=schema.FieldElementType("DATE")
        )

References

1. Do not import modules or classes inside functions if they are already imported at the module level.

[chalmerlowe]

Done! Removed the local import and referenced schema.FieldElementType directly.

[tswast]

Thanks!