def test_resample_how_callables(self):
        # GH 7929
        data = np.arange(5, dtype=np.int64)
        ind = pd.DatetimeIndex(start='2014-01-01', periods=len(data), freq='d')
        df = pd.DataFrame({"A": data, "B": data}, index=ind)

        def fn(x, a=1):
            return str(type(x))

        class fn_class:
            def __call__(self, x):
                return str(type(x))

        df_standard = df.resample("M", how=fn)
        df_lambda = df.resample("M", how=lambda x: str(type(x)))
        df_partial = df.resample("M", how=partial(fn))
        df_partial2 = df.resample("M", how=partial(fn, a=2))
        df_class = df.resample("M", how=fn_class())

        assert_frame_equal(df_standard, df_lambda)
        assert_frame_equal(df_standard, df_partial)
        assert_frame_equal(df_standard, df_partial2)
        assert_frame_equal(df_standard, df_class)