handle server inconsistency and unit tests

Author: Linchin

google/cloud/bigquery/schema.py

@@ -279,6 +279,15 @@ def from_api_repr(cls, api_repr: dict) -> "SchemaField":
         """
         placeholder = cls("this_will_be_replaced", "PLACEHOLDER")
 
+        # The API would return a string despite we send an integer. To ensure
+        # success of resending received schema, we convert string to integer
+        # to ensure consistency.
+        if (
+            isinstance(api_repr, dict)
+            and type(api_repr.get("timestampPrecision")) is str
+        ):
+            api_repr["timestampPrecision"] = int(api_repr["timestampPrecision"])
+
         # Note: we don't make a copy of api_repr because this can cause
         # unnecessary slowdowns, especially on deeply nested STRUCT / RECORD
         # fields. See https://github.com/googleapis/python-bigquery/issues/6

tests/unit/test_schema.py

@@ -294,6 +294,17 @@ def test_from_api_repr_defaults(self):
         self.assertNotIn("policyTags", field._properties)
         self.assertNotIn("rangeElementType", field._properties)
 
+    def test_from_api_repr_timestamp_precision_str(self):
+        # The backend would return timestampPrecision field as a string, even
+        # if we send over an integer. This test verifies we manually converted
+        # it into integer to ensure resending could succeed.
+        field = self._get_target_class().from_api_repr(
+            {
+                "timestampPrecision": "12",
+            }
+        )
+        self.assertEqual(field._properties["timestampPrecision"], 12)
+
     def test_name_property(self):
         name = "lemon-ness"
         schema_field = self._make_one(name, "INTEGER")
@@ -353,6 +364,14 @@ def test_foreign_type_definition_property_str(self):
         schema_field._properties["foreignTypeDefinition"] = FOREIGN_TYPE_DEFINITION
         self.assertEqual(schema_field.foreign_type_definition, FOREIGN_TYPE_DEFINITION)
 
+    def test_timestamp_precision_unsupported_type(self):
+        with pytest.raises(ValueError) as e:
+            self._make_one("test", "TIMESTAMP", timestamp_precision=12)
+
+        assert "timestamp_precision must be class enums.TimestampPrecision" in str(
+            e.value
+        )
+
     def test_timestamp_precision_property(self):
         TIMESTAMP_PRECISION = enums.TimestampPrecision.PICOSECOND
         schema_field = self._make_one("test", "TIMESTAMP")