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_ios.py

@@ -3,6 +3,7 @@ import platform
 import shutil
 import subprocess
 import textwrap
+from pathlib import Path
 
 import pytest
 
@@ -22,7 +23,7 @@ import platform
 from unittest import TestCase
 
 class TestPlatform(TestCase):
-    def test_platform(self):
+    def test_platform(self) -> None:
         self.assertEqual(platform.machine(), "{platform.machine()}")
 
 """
@@ -59,7 +60,12 @@ def skip_if_ios_testing_not_supported() -> None:
         {"CIBW_PLATFORM": "ios", "CIBW_BUILD_FRONTEND": "build"},
     ],
 )
-def test_ios_platforms(tmp_path, build_config, monkeypatch, capfd):
+def test_ios_platforms(
+    tmp_path: Path,
+    build_config: dict[str, str],
+    monkeypatch: pytest.MonkeyPatch,
+    capfd: pytest.CaptureFixture[str],
+) -> None:
     skip_if_ios_testing_not_supported()
 
     # Create a temporary "bin" directory, symlink a tool that we know eixsts
@@ -67,7 +73,9 @@ def test_ios_platforms(tmp_path, build_config, monkeypatch, capfd):
     # and add the temp bin directory to the PATH.
     tools_dir = tmp_path / "bin"
     tools_dir.mkdir()
-    tools_dir.joinpath("does-exist").symlink_to(shutil.which("true"))
+    true_app = shutil.which("true")
+    assert true_app is not None
+    tools_dir.joinpath("does-exist").symlink_to(true_app)
 
     monkeypatch.setenv("PATH", str(tools_dir), prepend=os.pathsep)
 
@@ -110,7 +118,7 @@ def test_ios_platforms(tmp_path, build_config, monkeypatch, capfd):
 
 
 @pytest.mark.serial
-def test_no_test_sources(tmp_path, capfd):
+def test_no_test_sources(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     """Build will provide a helpful error if pytest is run and test-sources is not defined."""
     skip_if_ios_testing_not_supported()
 
@@ -138,7 +146,7 @@ def test_no_test_sources(tmp_path, capfd):
     )
 
 
-def test_ios_testing_with_placeholder(tmp_path, capfd):
+def test_ios_testing_with_placeholder(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     """
     Tests with the {project} placeholder are not supported on iOS, because the test command
     is run in the simulator.
@@ -168,7 +176,7 @@ def test_ios_testing_with_placeholder(tmp_path, capfd):
 
 @pytest.mark.serial
 @pytest.mark.flaky(reruns=2)
-def test_ios_test_command_short_circuit(tmp_path, capfd):
+def test_ios_test_command_short_circuit(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     skip_if_ios_testing_not_supported()
 
     project_dir = tmp_path / "project"
@@ -196,7 +204,7 @@ def test_ios_test_command_short_circuit(tmp_path, capfd):
     assert "Zen of Python" not in captured.out + captured.err
 
 
-def test_missing_xbuild_tool(tmp_path, capfd):
+def test_missing_xbuild_tool(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     """Build will fail if xbuild-tools references a non-existent tool."""
     skip_if_ios_testing_not_supported()
 
@@ -220,7 +228,7 @@ def test_missing_xbuild_tool(tmp_path, capfd):
     assert "Could not find a 'does-not-exist' executable on the path." in captured.err
 
 
-def test_no_xbuild_tool_definition(tmp_path, capfd):
+def test_no_xbuild_tool_definition(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     """Build will succeed with a warning if there is no xbuild-tools definition."""
     skip_if_ios_testing_not_supported()
 
@@ -254,7 +262,7 @@ def test_no_xbuild_tool_definition(tmp_path, capfd):
     assert "Your project configuration does not define any cross-build tools." in captured.err
 
 
-def test_empty_xbuild_tool_definition(tmp_path, capfd):
+def test_empty_xbuild_tool_definition(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     """Build will succeed with no warning if there is an empty xbuild-tools definition."""
     skip_if_ios_testing_not_supported()
 
@@ -286,7 +294,9 @@ def test_empty_xbuild_tool_definition(tmp_path, capfd):
 
 
 @pytest.mark.serial
-def test_ios_test_command_without_python_dash_m(tmp_path, capfd):
+def test_ios_test_command_without_python_dash_m(
+    tmp_path: Path, capfd: pytest.CaptureFixture[str]
+) -> None:
     """pytest should be able to run without python -m, but it should warn."""
     skip_if_ios_testing_not_supported()
 
@@ -296,7 +306,7 @@ def test_ios_test_command_without_python_dash_m(tmp_path, capfd):
     project.files["tests/__init__.py"] = ""
     project.files["tests/test_spam.py"] = textwrap.dedent("""
         import spam
-        def test_spam():
+        def test_spam() -> None:
             assert spam.filter("spam") == 0
             assert spam.filter("ham") != 0
     """)
@@ -324,7 +334,7 @@ def test_ios_test_command_without_python_dash_m(tmp_path, capfd):
     assert "iOS tests configured with a test command which doesn't start with 'python -m'" in err
 
 
-def test_ios_test_command_invalid(tmp_path, capfd):
+def test_ios_test_command_invalid(tmp_path: Path, capfd: pytest.CaptureFixture[str]) -> None:
     """Test command should raise an error if it's clearly invalid."""
     skip_if_ios_testing_not_supported()
 
@@ -347,7 +357,7 @@ def test_ios_test_command_invalid(tmp_path, capfd):
     assert "iOS tests configured with a test command which doesn't start with 'python -m'" in err
 
 
-def test_repair_step(tmp_path):
+def test_repair_step(tmp_path: Path) -> None:
     """Build will succeed & the custom repair step is called."""
     skip_if_ios_testing_not_supported()