Improve doc/typing/message for `ExceptionInfo.match` (#6776)

src/_pytest/_code/code.py

@@ -633,17 +633,18 @@ class ExceptionInfo(Generic[_E]):
         )
         return fmt.repr_excinfo(self)
 
-    def match(self, regexp: "Union[str, Pattern]") -> bool:
+    def match(self, regexp: "Union[str, Pattern]") -> "Literal[True]":
         """
-        Check whether the regular expression 'regexp' is found in the string
+        Check whether the regular expression `regexp` matches the string
-        representation of the exception using ``re.search``. If it matches
+        representation of the exception using :func:`python:re.search`.
-        then True is returned (so that it is possible to write
+        If it matches `True` is returned.
-        ``assert excinfo.match()``). If it doesn't match an AssertionError is
+        If it doesn't match an `AssertionError` is raised.
-        raised.
         """
         __tracebackhide__ = True
-        if not re.search(regexp, str(self.value)):
+        assert re.search(
-            assert 0, "Pattern {!r} not found in {!r}".format(regexp, str(self.value))
+            regexp, str(self.value)
+        ), "Pattern {!r} does not match {!r}".format(regexp, str(self.value))
+        # Return True to allow for "assert excinfo.match()".
         return True
 
 

testing/code/test_excinfo.py

@@ -411,13 +411,15 @@ def test_match_raises_error(testdir):
     )
     result = testdir.runpytest()
     assert result.ret != 0
-    result.stdout.fnmatch_lines(["*AssertionError*Pattern*[123]*not found*"])
+
+    exc_msg = "Pattern '[[]123[]]+' does not match 'division by zero'"
+    result.stdout.fnmatch_lines(["E * AssertionError: {}".format(exc_msg)])
     result.stdout.no_fnmatch_line("*__tracebackhide__ = True*")
 
     result = testdir.runpytest("--fulltrace")
     assert result.ret != 0
     result.stdout.fnmatch_lines(
-        ["*__tracebackhide__ = True*", "*AssertionError*Pattern*[123]*not found*"]
+        ["*__tracebackhide__ = True*", "E * AssertionError: {}".format(exc_msg)]
     )
 
 

testing/python/raises.py

@@ -194,7 +194,7 @@ class TestRaises:
             int("asdf")
 
         msg = "with base 16"
-        expr = r"Pattern '{}' not found in \"invalid literal for int\(\) with base 10: 'asdf'\"".format(
+        expr = r"Pattern '{}' does not match \"invalid literal for int\(\) with base 10: 'asdf'\"".format(
             msg
         )
         with pytest.raises(AssertionError, match=expr):
@@ -206,7 +206,7 @@ class TestRaises:
             with pytest.raises(AssertionError, match="'foo"):
                 raise AssertionError("'bar")
         (msg,) = excinfo.value.args
-        assert msg == 'Pattern "\'foo" not found in "\'bar"'
+        assert msg == 'Pattern "\'foo" does not match "\'bar"'
 
     def test_raises_match_wrong_type(self):
         """Raising an exception with the wrong type and match= given.