Proof of concept

src/_pytest/_code/code.py

@@ -704,7 +704,12 @@ class ExceptionInfo(Generic[E]):
         If it matches `True` is returned, otherwise an `AssertionError` is raised.
         """
         __tracebackhide__ = True
-        value = str(self.value)
+        value = "\n".join(
+            [
+                str(self.value),
+                *getattr(self.value, "__notes__", []),
+            ]
+        )
         msg = f"Regex pattern did not match.\n Regex: {regexp!r}\n Input: {value!r}"
         if regexp == value:
             msg += "\n Did you mean to `re.escape()` the regex?"

testing/code/test_excinfo.py

@@ -1648,3 +1648,38 @@ def test_hidden_entries_of_chained_exceptions_are_not_shown(pytester: Pytester)
         ],
         consecutive=True,
     )
+
+
+@pytest.mark.skip("sys.version_info < (3,11)")
+@pytest.mark.parametrize(
+    "error,notes,match",
+    [
+        (Exception("test"), [], "test"),
+        (AssertionError("foo"), ["bar"], "bar"),
+        (AssertionError("foo"), ["bar", "baz"], "bar"),
+        (AssertionError("foo"), ["bar", "baz"], "baz"),
+    ],
+)
+def test_check_error_notes_success(error, notes, match):
+    for note in notes:
+        error.add_note(note)
+
+    with pytest.raises(Exception, match=match):
+        raise error
+
+
+@pytest.mark.skip("sys.version_info < (3,11)")
+@pytest.mark.parametrize(
+    "error, notes, match",
+    [
+        (Exception("test"), [], "foo"),
+        (AssertionError("foo"), ["bar"], "baz"),
+    ],
+)
+def test_check_error_notes_failure(error, notes, match):
+    for note in notes:
+        error.add_note(note)
+
+    with pytest.raises(AssertionError):
+        with pytest.raises(type(error), match=match):
+            raise error