DOC: add examples to docstrings of assert_ functions (#37844)

Co-authored-by: Marco Gorelli <[email protected]>

Author: nguevara

pandas/_testing.py

@@ -739,6 +739,13 @@ def assert_index_equal(
     obj : str, default 'Index'
         Specify object name being compared, internally used to show appropriate
         assertion message.
+
+    Examples
+    --------
+    >>> from pandas.testing import assert_index_equal
+    >>> a = pd.Index([1, 2, 3])
+    >>> b = pd.Index([1, 2, 3])
+    >>> assert_index_equal(a, b)
     """
     __tracebackhide__ = True
 
@@ -1205,6 +1212,13 @@ def assert_extension_array_equal(
     Missing values are checked separately from valid values.
     A mask of missing values is computed for each and checked to match.
     The remaining all-valid values are cast to object dtype and checked.
+
+    Examples
+    --------
+    >>> from pandas.testing import assert_extension_array_equal
+    >>> a = pd.Series([1, 2, 3, 4])
+    >>> b, c = a.array, a.array
+    >>> assert_extension_array_equal(b, c)
     """
     if check_less_precise is not no_default:
         warnings.warn(
@@ -1334,6 +1348,13 @@ def assert_series_equal(
     obj : str, default 'Series'
         Specify object name being compared, internally used to show appropriate
         assertion message.
+
+    Examples
+    --------
+    >>> from pandas.testing import assert_series_equal
+    >>> a = pd.Series([1, 2, 3, 4])
+    >>> b = pd.Series([1, 2, 3, 4])
+    >>> assert_series_equal(a, b)
     """
     __tracebackhide__ = True