add test for depr is_copy

pandas/tests/generic/test_generic.py

@@ -820,6 +820,18 @@ def test_take_invalid_kwargs(self):
             with pytest.raises(ValueError, match=msg):
                 obj.take(indices, mode="clip")
 
+    def test_depr_take_kwarg_is_copy(self):
+        # GH 27357
+        df = DataFrame({"A": [1, 2, 3]})
+        msg = (
+            "is_copy is deprecated and will be removed in a future version. "
+            "take will always return a copy in the future."
+        )
+        with tm.assert_produces_warning(FutureWarning) as w:
+            df.take([0, 1], is_copy=True)
+
+        assert w[0].message.args[0] == msg
+
     def test_equals(self):
         s1 = pd.Series([1, 2, 3], index=[0, 2, 1])
         s2 = s1.copy()