using classmethods now

pandas/tests/extension/base/base.py

@@ -2,15 +2,20 @@
 
 
 class BaseExtensionTests:
-    # can't use staticmethod() as this confuses mypy
-    def assert_equal(self, left, right, **kwargs):
+    # classmethod and different signature is needed
+    # to make inheritance compliant with mypy
+    @classmethod
+    def assert_equal(cls, left, right, **kwargs):
         return tm.assert_equal(left, right, **kwargs)
 
-    def assert_series_equal(self, left, right, *args, **kwargs):
+    @classmethod
+    def assert_series_equal(cls, left, right, *args, **kwargs):
         return tm.assert_series_equal(left, right, *args, **kwargs)
 
-    def assert_frame_equal(self, left, right, *args, **kwargs):
+    @classmethod
+    def assert_frame_equal(cls, left, right, *args, **kwargs):
         return tm.assert_frame_equal(left, right, *args, **kwargs)
 
-    def assert_extension_array_equal(self, left, right, *args, **kwargs):
+    @classmethod
+    def assert_extension_array_equal(cls, left, right, *args, **kwargs):
         return tm.assert_extension_array_equal(left, right, *args, **kwargs)

pandas/tests/extension/decimal/test_decimal.py

@@ -66,7 +66,8 @@ def data_for_grouping():
 
 
 class BaseDecimal:
-    def assert_series_equal(self, left, right, *args, **kwargs):
+    @classmethod
+    def assert_series_equal(cls, left, right, *args, **kwargs):
         def convert(x):
             # need to convert array([Decimal(NaN)], dtype='object') to np.NaN
             # because Series[object].isnan doesn't recognize decimal(NaN) as
@@ -88,7 +89,8 @@ def convert(x):
         tm.assert_series_equal(left_na, right_na)
         return tm.assert_series_equal(left[~left_na], right[~right_na], *args, **kwargs)
 
-    def assert_frame_equal(self, left, right, *args, **kwargs):
+    @classmethod
+    def assert_frame_equal(cls, left, right, *args, **kwargs):
         # TODO(EA): select_dtypes
         tm.assert_index_equal(
             left.columns,
@@ -103,7 +105,7 @@ def assert_frame_equal(self, left, right, *args, **kwargs):
         decimals = (left.dtypes == "decimal").index
 
         for col in decimals:
-            self.assert_series_equal(left[col], right[col], *args, **kwargs)
+            cls.assert_series_equal(left[col], right[col], *args, **kwargs)
 
         left = left.drop(columns=decimals)
         right = right.drop(columns=decimals)