Enhance errors for exception/warnings matching (#8508)

Co-authored-by: Florian Bruhin <me@the-compiler.org>

testing/code/test_excinfo.py

@@ -420,18 +420,20 @@ def test_match_raises_error(pytester: Pytester) -> None:
             excinfo.match(r'[123]+')
     """
     )
-    result = pytester.runpytest()
+    result = pytester.runpytest("--tb=short")
     assert result.ret != 0
 
-    exc_msg = "Regex pattern '[[]123[]]+' does not match 'division by zero'."
-    result.stdout.fnmatch_lines([f"E * AssertionError: {exc_msg}"])
+    match = [
+        r"E .* AssertionError: Regex pattern did not match.",
+        r"E .* Regex: '\[123\]\+'",
+        r"E .* Input: 'division by zero'",
+    ]
+    result.stdout.re_match_lines(match)
     result.stdout.no_fnmatch_line("*__tracebackhide__ = True*")
 
     result = pytester.runpytest("--fulltrace")
     assert result.ret != 0
-    result.stdout.fnmatch_lines(
-        ["*__tracebackhide__ = True*", f"E * AssertionError: {exc_msg}"]
-    )
+    result.stdout.re_match_lines([r".*__tracebackhide__ = True.*", *match])
 
 
 class TestFormattedExcinfo:

testing/python/raises.py

@@ -191,10 +191,12 @@ class TestRaises:
             int("asdf")
 
         msg = "with base 16"
-        expr = "Regex pattern {!r} does not match \"invalid literal for int() with base 10: 'asdf'\".".format(
-            msg
+        expr = (
+            "Regex pattern did not match.\n"
+            f" Regex: {msg!r}\n"
+            " Input: \"invalid literal for int() with base 10: 'asdf'\""
         )
-        with pytest.raises(AssertionError, match=re.escape(expr)):
+        with pytest.raises(AssertionError, match="(?m)" + re.escape(expr)):
             with pytest.raises(ValueError, match=msg):
                 int("asdf", base=10)
 
@@ -217,7 +219,7 @@ class TestRaises:
             with pytest.raises(AssertionError, match="'foo"):
                 raise AssertionError("'bar")
         (msg,) = excinfo.value.args
-        assert msg == 'Regex pattern "\'foo" does not match "\'bar".'
+        assert msg == '''Regex pattern did not match.\n Regex: "'foo"\n Input: "'bar"'''
 
     def test_match_failure_exact_string_message(self):
         message = "Oh here is a message with (42) numbers in parameters"
@@ -226,9 +228,10 @@ class TestRaises:
                 raise AssertionError(message)
         (msg,) = excinfo.value.args
         assert msg == (
-            "Regex pattern 'Oh here is a message with (42) numbers in "
-            "parameters' does not match 'Oh here is a message with (42) "
-            "numbers in parameters'. Did you mean to `re.escape()` the regex?"
+            "Regex pattern did not match.\n"
+            " Regex: 'Oh here is a message with (42) numbers in parameters'\n"
+            " Input: 'Oh here is a message with (42) numbers in parameters'\n"
+            " Did you mean to `re.escape()` the regex?"
         )
 
     def test_raises_match_wrong_type(self):

testing/test_recwarn.py

@@ -1,4 +1,3 @@
-import re
 import warnings
 from typing import Optional
 
@@ -263,7 +262,7 @@ class TestWarns:
             with pytest.warns(RuntimeWarning):
                 warnings.warn("user", UserWarning)
         excinfo.match(
-            r"DID NOT WARN. No warnings of type \(.+RuntimeWarning.+,\) were emitted. "
+            r"DID NOT WARN. No warnings of type \(.+RuntimeWarning.+,\) were emitted.\n"
             r"The list of emitted warnings is: \[UserWarning\('user',?\)\]."
         )
 
@@ -271,15 +270,15 @@ class TestWarns:
             with pytest.warns(UserWarning):
                 warnings.warn("runtime", RuntimeWarning)
         excinfo.match(
-            r"DID NOT WARN. No warnings of type \(.+UserWarning.+,\) were emitted. "
-            r"The list of emitted warnings is: \[RuntimeWarning\('runtime',?\)\]."
+            r"DID NOT WARN. No warnings of type \(.+UserWarning.+,\) were emitted.\n"
+            r"The list of emitted warnings is: \[RuntimeWarning\('runtime',?\)]."
         )
 
         with pytest.raises(pytest.fail.Exception) as excinfo:
             with pytest.warns(UserWarning):
                 pass
         excinfo.match(
-            r"DID NOT WARN. No warnings of type \(.+UserWarning.+,\) were emitted. "
+            r"DID NOT WARN. No warnings of type \(.+UserWarning.+,\) were emitted.\n"
             r"The list of emitted warnings is: \[\]."
         )
 
@@ -289,18 +288,14 @@ class TestWarns:
                 warnings.warn("runtime", RuntimeWarning)
                 warnings.warn("import", ImportWarning)
 
-        message_template = (
-            "DID NOT WARN. No warnings of type {0} were emitted. "
-            "The list of emitted warnings is: {1}."
-        )
-        excinfo.match(
-            re.escape(
-                message_template.format(
-                    warning_classes, [each.message for each in warninfo]
-                )
-            )
+        messages = [each.message for each in warninfo]
+        expected_str = (
+            f"DID NOT WARN. No warnings of type {warning_classes} were emitted.\n"
+            f"The list of emitted warnings is: {messages}."
         )
 
+        assert str(excinfo.value) == expected_str
+
     def test_record(self) -> None:
         with pytest.warns(UserWarning) as record:
             warnings.warn("user", UserWarning)