tests: fully type the test suite (#2794)

* tests: fully type the test suite

* chore: require more typing

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Signed-off-by: Henry Schreiner <henryfs@princeton.edu>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

test/test_0_basic.py

@@ -1,4 +1,5 @@
 import textwrap
+from pathlib import Path
 
 import packaging.utils
 import pytest
@@ -21,7 +22,7 @@ basic_project = test_projects.new_c_project(
 
 
 @pytest.mark.serial
-def test_dummy_serial():
+def test_dummy_serial() -> None:
     """A no-op test to ensure that at least one serial test is always found.
 
     Without this no-op test, CI fails on CircleCI because no serial tests are
@@ -29,7 +30,9 @@ def test_dummy_serial():
     """
 
 
-def test(tmp_path, build_frontend_env, capfd):
+def test(
+    tmp_path: Path, build_frontend_env: dict[str, str], capfd: pytest.CaptureFixture[str]
+) -> None:
     project_dir = tmp_path / "project"
     basic_project.generate(project_dir)
 
@@ -52,7 +55,7 @@ def test(tmp_path, build_frontend_env, capfd):
 
 
 @pytest.mark.skip(reason="to keep test output clean")
-def test_sample_build(tmp_path, capfd):
+def test_sample_build(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     project_dir = tmp_path / "project"
     basic_project.generate(project_dir)
 
@@ -70,7 +73,9 @@ def test_sample_build(tmp_path, capfd):
 @pytest.mark.parametrize(
     "enable_setting", ["", "cpython-prerelease", "pypy", "cpython-freethreading"]
 )
-def test_build_identifiers(tmp_path, enable_setting, monkeypatch):
+def test_build_identifiers(
+    tmp_path: Path, enable_setting: str, monkeypatch: pytest.MonkeyPatch
+) -> None:
     project_dir = tmp_path / "project"
     basic_project.generate(project_dir)
 
@@ -93,7 +98,9 @@ def test_build_identifiers(tmp_path, enable_setting, monkeypatch):
         (None, {"CIBW_ALLOW_EMPTY": "1"}),
     ],
 )
-def test_allow_empty(tmp_path, add_args, env_allow_empty):
+def test_allow_empty(
+    tmp_path: Path, add_args: list[str] | None, env_allow_empty: dict[str, str]
+) -> None:
     project_dir = tmp_path / "project"
     basic_project.generate(project_dir)