feat: enable mypy session for db-dtypes

Author: chalmerlowe

packages/db-dtypes/db_dtypes/core.py

@@ -58,7 +58,7 @@ def __init__(self, values, dtype=None, copy: bool = False):
         elif copy:
             values = values.copy()
 
-        super().__init__(values=values, dtype=values.dtype)
+        super().__init__(values=values, dtype=values.dtype)  # type: ignore[call-arg]
 
     @classmethod
     def __ndarray(cls, scalars):
@@ -164,17 +164,17 @@ def min(self, *, axis: Optional[int] = None, skipna: bool = True, **kwargs):
             values=self._ndarray, axis=axis, mask=self.isna(), skipna=skipna
         )
         if axis is None or self.ndim == 1:
-            return self._box_func(result)
-        return self._from_backing_data(result)
+            return self._box_func(result)  # type: ignore[attr-defined]
+        return self._from_backing_data(result)  # type: ignore[attr-defined]
 
     def max(self, *, axis: Optional[int] = None, skipna: bool = True, **kwargs):
         pandas_backports.numpy_validate_max((), kwargs)
         result = pandas_backports.nanmax(
             values=self._ndarray, axis=axis, mask=self.isna(), skipna=skipna
         )
         if axis is None or self.ndim == 1:
-            return self._box_func(result)
-        return self._from_backing_data(result)
+            return self._box_func(result)  # type: ignore[attr-defined]
+        return self._from_backing_data(result)  # type: ignore[attr-defined]
 
     def median(
         self,
@@ -191,5 +191,5 @@ def median(
         )
         result = pandas_backports.nanmedian(self._ndarray, axis=axis, skipna=skipna)
         if axis is None or self.ndim == 1:
-            return self._box_func(result)
-        return self._from_backing_data(result)
+            return self._box_func(result)  # type: ignore[attr-defined]
+        return self._from_backing_data(result)  # type: ignore[attr-defined]

packages/db-dtypes/db_dtypes/json.py

@@ -32,12 +32,12 @@ class JSONDtype(pd.api.extensions.ExtensionDtype):
     name = "dbjson"
 
     @property
-    def na_value(self) -> pd.NA:
+    def na_value(self) -> pd.NA:  # type: ignore[valid-type]
         """Default NA value to use for this type."""
         return pd.NA
 
     @property
-    def type(self) -> type[str]:
+    def type(self) -> type[str]:  # type: ignore[override]
         """
         Return the scalar type for the array elements.
         The standard JSON data types can be one of `dict`, `list`, `str`, `int`, `float`,

packages/db-dtypes/db_dtypes/pandas_backports.py

@@ -26,16 +26,16 @@
 pandas_release = packaging.version.parse(pandas.__version__).release
 
 # # Create aliases for private methods in case they move in a future version.
-nanall = pandas.core.nanops.nanall
-nanany = pandas.core.nanops.nanany
-nanmax = pandas.core.nanops.nanmax
-nanmin = pandas.core.nanops.nanmin
+nanall = pandas.core.nanops.nanall  # type: ignore[attr-defined]
+nanany = pandas.core.nanops.nanany  # type: ignore[attr-defined]
+nanmax = pandas.core.nanops.nanmax  # type: ignore[attr-defined]
+nanmin = pandas.core.nanops.nanmin  # type: ignore[attr-defined]
 numpy_validate_all = pandas.compat.numpy.function.validate_all
 numpy_validate_any = pandas.compat.numpy.function.validate_any
 numpy_validate_max = pandas.compat.numpy.function.validate_max
 numpy_validate_min = pandas.compat.numpy.function.validate_min
 
-nanmedian = pandas.core.nanops.nanmedian
+nanmedian = pandas.core.nanops.nanmedian  # type: ignore[attr-defined]
 numpy_validate_median = pandas.compat.numpy.function.validate_median
 
 

packages/db-dtypes/noxfile.py

@@ -487,6 +487,18 @@ def core_deps_from_source(session):
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def mypy(session):
     """Run the type checker."""
-    # TODO(https://github.com/googleapis/google-cloud-python/issues/16014):
-    # Add mypy tests
-    session.skip("mypy tests are not yet supported")
+    session.install(
+        "mypy<1.16.0",
+        "types-requests",
+        "types-protobuf",
+        "pandas-stubs",
+    )
+    session.install("-e", ".")
+    session.run(
+        "mypy",
+        "-p",
+        "db_dtypes",
+        "--check-untyped-defs",
+        "--ignore-missing-imports",
+        *session.posargs,
+    )