From 231d06d105fe37e80fbb8d293bf854b719832d5a Mon Sep 17 00:00:00 2001
From: Stephen Finucane <stephen@that.guru>
Date: Sun, 5 Apr 2026 21:07:32 +0100
Subject: [PATCH 1/2] typing: Fix compatibility with mypy 1.20.0

Beyond some tweaks to `type: ignore` comments, we need to disable the
`warn_unused_configs = true` option to work around [1]. We also take the
opportunity to drop the unnecessary `warn_unused_ignores = true` option
which is already handled by `strict = true`

[1] https://github.com/python/mypy/issues/21137

Signed-off-by: Stephen Finucane <stephen@that.guru>
---
 pyproject.toml         | 6 ++++--
 testtools/testcase.py  | 4 ++--
 testtools/testsuite.py | 2 +-
 tox.ini                | 2 +-
 4 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/pyproject.toml b/pyproject.toml
index 67782eee..68fb18c6 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -38,7 +38,7 @@ test = ["testscenarios", "testresources"]
 twisted = ["Twisted", "fixtures"]
 dev = [
     "ruff==0.15.8",
-    "mypy>=1.0.0",
+    "mypy>=1.20.0",
     "typing-extensions;python_version<'3.11'",
 ]
 
@@ -63,7 +63,9 @@ python_version = "3.10"
 show_column_numbers = true
 show_error_context = true
 strict = true
-warn_unused_ignores = true
+# remove this when 1.20.1 is released
+# https://github.com/python/mypy/issues/21137
+warn_unused_configs = false
 # FIXME(stephenfin): We should remove this
 implicit_reexport = true
 exclude = 'doc'
diff --git a/testtools/testcase.py b/testtools/testcase.py
index e60ba339..746cb862 100644
--- a/testtools/testcase.py
+++ b/testtools/testcase.py
@@ -928,7 +928,7 @@ def _validate_setup_called(result: object) -> object:
                     )
                 return result
 
-            ret.addBoth(_validate_setup_called)
+            ret.addBoth(_validate_setup_called)  # type: ignore[attr-defined]
         else:
             # Synchronous: validate immediately
             if not self.__setup_called:
@@ -964,7 +964,7 @@ def _validate_teardown_called(result: object) -> object:
                     )
                 return result
 
-            ret.addBoth(_validate_teardown_called)
+            ret.addBoth(_validate_teardown_called)  # type: ignore[attr-defined]
         else:
             # Synchronous: validate immediately
             if not self.__teardown_called:
diff --git a/testtools/testsuite.py b/testtools/testsuite.py
index 119624df..8dcae5cd 100644
--- a/testtools/testsuite.py
+++ b/testtools/testsuite.py
@@ -62,7 +62,7 @@ def iterate_tests(
         for test in test_suite_or_case:
             yield from iterate_tests(test)
     else:
-        yield test_suite_or_case  # type: ignore[misc]
+        yield test_suite_or_case
 
 
 class ConcurrentTestSuite(unittest.TestSuite):
diff --git a/tox.ini b/tox.ini
index 6cf33bac..70e91ff5 100644
--- a/tox.ini
+++ b/tox.ini
@@ -19,6 +19,6 @@ commands =
 
 [testenv:mypy]
 deps =
-  mypy
+  mypy>=1.20.0
 commands =
   mypy --cache-dir="{envdir}/mypy_cache" {posargs:testtools}

From ec15b814161f0ffbd66f892194225f7f39d21910 Mon Sep 17 00:00:00 2001
From: Stephen Finucane <stephen@that.guru>
Date: Sun, 5 Apr 2026 00:07:57 +0100
Subject: [PATCH 2/2] typing: Make less use of ParamSpec

This is a partial revert of 107864786f8a40af7984f8cc0638751a42f341e5.
mypy (and possibly others) are not able to correctly resolve a ParamSpec
for an overridden method. This causes a lot of false positives when
using assertRaises (as a function) on methods with overrides, which
cannot be resolved except through `type: ignore` statements. In
addition, it's often desirable to test functions with incorrect types to
assert runtime validation. Given these two issues, it's easier to just
drop the use of ParamSpec.

Signed-off-by: Stephen Finucane <stephen@that.guru>
---
 testtools/testcase.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/testtools/testcase.py b/testtools/testcase.py
index 746cb862..bdd640a9 100644
--- a/testtools/testcase.py
+++ b/testtools/testcase.py
@@ -577,18 +577,18 @@ def assertIsInstance(  # type: ignore[override]
     def assertRaises(
         self,
         expected_exception: type[_E],
-        callable: Callable[_P, _R],
-        *args: _P.args,
-        **kwargs: _P.kwargs,
+        callable: Callable[..., Any],
+        *args: Any,
+        **kwargs: Any,
     ) -> _E: ...
 
     @overload
     def assertRaises(
         self,
         expected_exception: tuple[type[BaseException], ...],
-        callable: Callable[_P, _R],
-        *args: _P.args,
-        **kwargs: _P.kwargs,
+        callable: Callable[..., Any],
+        *args: Any,
+        **kwargs: Any,
     ) -> BaseException: ...
 
     @overload