feat: adds ForeignTypeInfo test (#2076)

* likely gonna delete this branch cause TestTableSchema may not be necessary

* Adds ForeignTypeInfo test_from_api_repr

* 🦉 Updates from OwlBot post-processor

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* 🦉 Updates from OwlBot post-processor

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* fixes merge conflict

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

google/cloud/bigquery/schema.py

@@ -24,7 +24,6 @@
 from google.cloud.bigquery import standard_sql
 from google.cloud.bigquery._helpers import (
     _isinstance_or_raise,
-    _from_api_repr,
     _get_sub_prop,
 )
 from google.cloud.bigquery.enums import StandardSqlTypeNames
@@ -501,6 +500,7 @@ def _to_schema_fields(schema):
         sequence is not a :class:`~google.cloud.bigquery.schema.SchemaField`
         instance or a compatible mapping representation of the field.
     """
+
     for field in schema:
         if not isinstance(field, (SchemaField, collections.abc.Mapping)):
             raise ValueError(
@@ -598,61 +598,6 @@ def to_api_repr(self) -> dict:
         return answer
 
 
-class TableSchema:
-    """Schema of a table
-
-    Args:
-        fields (Optional[list]): Describes the fields in a table.
-        foreignTypeInfo (Optional[str]): Specifies metadata of the foreign data type
-            definition in field schema.
-    """
-
-    def __init__(
-        self, fields: Optional[list] = None, foreign_type_info: Optional[str] = None
-    ):
-        self._properties: Dict[str, Any] = {}
-        self.fields = fields
-        self.foreign_type_info = foreign_type_info
-
-    @property
-    def fields(self) -> Any:
-        """Describes the fields in a table."""
-
-        return self._properties.get("fields")
-
-    @fields.setter
-    def fields(self, value: list, dtype: str) -> None:
-        value = _isinstance_or_raise(value, list, none_allowed=True)
-        self._properties["fields"] = value
-
-    @property
-    def foreign_type_info(self) -> Any:
-        """Optional. Specifies metadata of the foreign data type definition in
-        field schema (TableFieldSchema.foreign_type_definition)."""
-
-        return self._properties.get("foreignTypeInfo")
-
-    @foreign_type_info.setter
-    def foreign_type_info(self, value: str, dtype: str) -> None:
-        if not isinstance(value, str):
-            raise ValueError(
-                f"Pass {value} as a '{repr(dtype)}'." f"Got {type(value)}."
-            )
-        self._properties["foreignTypeInfo"] = value
-
-    def to_api_repr(self) -> dict:
-        """Build an API representation of this object.
-
-        Returns:
-            Dict[str, Any]:
-                A dictionary in the format used by the BigQuery API.
-        """
-        return copy.deepcopy(self._properties)
-
-    def from_api_repr(self, resource):
-        return _from_api_repr(self, resource)
-
-
 class ForeignTypeInfo:
     """Metadata about the foreign data type definition such as the system in which the
     type is defined.
@@ -687,8 +632,21 @@ def to_api_repr(self) -> dict:
         """
         return copy.deepcopy(self._properties)
 
-    def from_api_repr(self, resource):
-        return _from_api_repr(self, resource)
+    @classmethod
+    def from_api_repr(cls, resource):
+        """Factory: constructs an instance of the class (cls)
+        given its API representation.
+
+        Args:
+            resource (Dict[str, Any]):
+                API representation of the object to be instantiated.
+
+        Returns:
+            An instance of the class initialized with data from 'resource'.
+        """
+        config = cls()
+        config._properties = copy.deepcopy(resource)
+        return config
 
 
 class StorageDescriptor:

tests/unit/test_schema.py

@@ -16,7 +16,7 @@
 from google.cloud.bigquery.standard_sql import StandardSqlStructType
 from google.cloud.bigquery.schema import (
     PolicyTagList,
-    # ForeignTypeInfo,
+    ForeignTypeInfo,
     StorageDescriptor,
     SerDeInfo,
 )
@@ -1121,8 +1121,6 @@ class TestForeignTypeInfo:
 
     @staticmethod
     def _get_target_class():
-        from google.cloud.bigquery.schema import ForeignTypeInfo
-
         return ForeignTypeInfo
 
     def _make_one(self, *args, **kw):
@@ -1160,6 +1158,22 @@ def test_to_api_repr(self, type_system, expected):
         result = self._make_one(type_system=type_system)
         assert result.to_api_repr() == expected
 
+    def test_from_api_repr(self):
+        """GIVEN an api representation of a ForeignTypeInfo object (i.e. resource)
+        WHEN converted into a ForeignTypeInfo object using from_api_repr() and
+        displayed as a dict
+        THEN it will have the same representation a ForeignTypeInfo object created
+        directly (via _make_one()) and displayed as a dict.
+        """
+        resource = {"typeSystem": "TYPE_SYSTEM_UNSPECIFIED"}
+
+        expected = self._make_one(type_system="TYPE_SYSTEM_UNSPECIFIED")
+
+        klass = self._get_target_class()
+        result = klass.from_api_repr(resource)
+
+        assert result.to_api_repr() == expected.to_api_repr()
+
 
 @pytest.fixture
 def _make_storage_descriptor():