TST: Fix assert_is_sorted for eas (#55536)

Author: phofl

pandas/_testing/asserters.py

@@ -440,7 +440,10 @@ def assert_is_sorted(seq) -> None:
     if isinstance(seq, (Index, Series)):
         seq = seq.values
     # sorting does not change precisions
-    assert_numpy_array_equal(seq, np.sort(np.array(seq)))
+    if isinstance(seq, np.ndarray):
+        assert_numpy_array_equal(seq, np.sort(np.array(seq)))
+    else:
+        assert_extension_array_equal(seq, seq[seq.argsort()])
 
 
 def assert_categorical_equal(

pandas/tests/util/test_util.py

@@ -2,7 +2,10 @@
 
 import pytest
 
-from pandas import compat
+from pandas import (
+    array,
+    compat,
+)
 import pandas._testing as tm
 
 
@@ -44,3 +47,12 @@ def test_datapath(datapath):
 def test_external_error_raised():
     with tm.external_error_raised(TypeError):
         raise TypeError("Should not check this error message, so it will pass")
+
+
+def test_is_sorted():
+    arr = array([1, 2, 3], dtype="Int64")
+    tm.assert_is_sorted(arr)
+
+    arr = array([4, 2, 3], dtype="Int64")
+    with pytest.raises(AssertionError, match="ExtensionArray are different"):
+        tm.assert_is_sorted(arr)