DOC: fixes for assert_frame_equal check_freq argument

doc/source/whatsnew/v1.1.0.rst

@@ -342,6 +342,21 @@ Other enhancements
 - ``compute.use_numba`` now exists as a configuration option that utilizes the numba engine when available (:issue:`33966`, :issue:`35374`)
 - :meth:`Series.plot` now supports asymmetric error bars. Previously, if :meth:`Series.plot` received a "2xN" array with error values for ``yerr`` and/or ``xerr``, the left/lower values (first row) were mirrored, while the right/upper values (second row) were ignored. Now, the first row represents the left/lower error values and the second row the right/upper error values. (:issue:`9536`)
 
+
+.. ---------------------------------------------------------------------------
+
+.. _whatsnew_110.api_breaking:
+
+Backwards incompatible API changes
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+.. _whatsnew_110.api_breaking._testing.assert_frame_equal:
+
+Added ``check_freq`` argument to ``assert_frame_equal``
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The ``check_freq`` argument was added to :func:`assert_frame_equal` and defaults to ``True``. :func:`assert_frame_equal` now raises ``AssertionError`` if the indexes do not have the same frequency. Before pandas 1.1.0, the index frequency was not checked by :func:`assert_frame_equal`.
+
 .. ---------------------------------------------------------------------------
 
 .. _whatsnew_110.notable_bug_fixes:

pandas/_testing.py

@@ -1576,6 +1576,8 @@ def assert_frame_equal(
         (same as in columns) - same labels must be with the same data.
     check_freq : bool, default True
         Whether to check the `freq` attribute on a DatetimeIndex or TimedeltaIndex.
+
+        .. versionadded:: 1.1.0
     check_flags : bool, default True
         Whether to check the `flags` attribute.
     rtol : float, default 1e-5