Add strict_na keyword to the assert_.._equal methods for object dtype to help with deprecation

pandas/_libs/testing.pyi

@@ -7,6 +7,7 @@ def assert_almost_equal(
     rtol: float = ...,
     atol: float = ...,
     check_dtype: bool = ...,
+    strict_na: bool = ...,
     obj=...,
     lobj=...,
     robj=...,

pandas/_libs/testing.pyx

@@ -52,7 +52,7 @@ cpdef assert_dict_equal(a, b, bint compare_keys=True):
 
 cpdef assert_almost_equal(a, b,
                           rtol=1.e-5, atol=1.e-8,
-                          bint check_dtype=True,
+                          bint check_dtype=True, bint strict_na=True,
                           obj=None, lobj=None, robj=None, index_values=None):
     """
     Check that left and right objects are almost equal.
@@ -67,6 +67,7 @@ cpdef assert_almost_equal(a, b,
         Absolute tolerance.
     check_dtype: bool, default True
         check dtype if both a and b are np.ndarray.
+    strict_na : bool, default True
     obj : str, default None
         Specify object name being compared, internally used to show
         appropriate assertion message.
@@ -155,7 +156,9 @@ cpdef assert_almost_equal(a, b,
 
         for i in range(len(a)):
             try:
-                assert_almost_equal(a[i], b[i], rtol=rtol, atol=atol)
+                assert_almost_equal(
+                    a[i], b[i], rtol=rtol, atol=atol, strict_na=strict_na
+                )
             except AssertionError:
                 is_unequal = True
                 diff += 1
@@ -185,8 +188,10 @@ cpdef assert_almost_equal(a, b,
         if is_matching_na(a, b, nan_matches_none=False):
             return True
         elif checknull(b):
-            # GH#18463
-            raise AssertionError(f"Mismatched null-like values {a} != {b}")
+            if strict_na:
+                raise AssertionError(f"Mismatched null-like values {a} != {b}")
+            else:
+                return True
         raise AssertionError(f"{a} != {b}")
     elif checknull(b):
         raise AssertionError(f"{a} != {b}")

pandas/_testing/asserters.py

@@ -69,6 +69,7 @@ def assert_almost_equal(
     check_dtype: bool | Literal["equiv"] = "equiv",
     rtol: float = 1.0e-5,
     atol: float = 1.0e-8,
+    strict_na: bool = True,
     **kwargs,
 ) -> None:
     """
@@ -89,6 +90,7 @@ def assert_almost_equal(
         Relative tolerance.
     atol : float, default 1e-8
         Absolute tolerance.
+    strict_na : bool, default True
     """
     if isinstance(left, Index):
         assert_index_equal(
@@ -141,7 +143,7 @@ def assert_almost_equal(
 
         # if we have "equiv", this becomes True
         _testing.assert_almost_equal(
-            left, right, check_dtype=bool(check_dtype), rtol=rtol, atol=atol, **kwargs
+            left, right, check_dtype=bool(check_dtype), rtol=rtol, atol=atol, strict_na=strict_na, **kwargs
         )
 
 
@@ -839,6 +841,7 @@ def assert_series_equal(
     check_flags: bool = True,
     rtol: float | lib.NoDefault = lib.no_default,
     atol: float | lib.NoDefault = lib.no_default,
+    strict_na: bool = True,
     obj: str = "Series",
     *,
     check_index: bool = True,
@@ -1070,6 +1073,7 @@ def assert_series_equal(
             rtol=rtol,
             atol=atol,
             check_dtype=bool(check_dtype),
+            strict_na=strict_na,
             obj=str(obj),
             index_values=left.index,
         )
@@ -1108,6 +1112,7 @@ def assert_frame_equal(
     check_flags: bool = True,
     rtol: float | lib.NoDefault = lib.no_default,
     atol: float | lib.NoDefault = lib.no_default,
+    strict_na: bool = True,
     obj: str = "DataFrame",
 ) -> None:
     """
@@ -1291,6 +1296,7 @@ def assert_frame_equal(
                 atol=atol,
                 check_index=False,
                 check_flags=False,
+                strict_na=strict_na,
             )
 
 

pandas/tests/util/test_assert_almost_equal.py

@@ -333,6 +333,8 @@ def test_mismatched_na_assert_almost_equal(left, right):
     else:
         with pytest.raises(AssertionError, match=msg):
             _assert_almost_equal_both(left, right, check_dtype=False)
+
+        _assert_almost_equal_both(left, right, check_dtype=False, strict_na=False)
 
         # TODO: to get the same deprecation in assert_numpy_array_equal we need
         #  to change/deprecate the default for strict_nan to become True
@@ -343,11 +345,17 @@ def test_mismatched_na_assert_almost_equal(left, right):
             tm.assert_series_equal(
                 Series(left_arr, dtype=object), Series(right_arr, dtype=object)
             )
+        tm.assert_series_equal(
+                Series(left_arr, dtype=object), Series(right_arr, dtype=object), strict_na=False
+            )
+
         with pytest.raises(AssertionError, match="DataFrame.iloc.* are different"):
             tm.assert_frame_equal(
                 DataFrame(left_arr, dtype=object), DataFrame(right_arr, dtype=object)
             )
-
+        tm.assert_frame_equal(
+                DataFrame(left_arr, dtype=object), DataFrame(right_arr, dtype=object), strict_na=False
+            )
 
 def test_assert_not_almost_equal_inf():
     _assert_not_almost_equal_both(np.inf, 0)