tests: Run Mypy against tests

Run Mypy static checks against our tests. This brings them inline with
the rest of the codebase, and we have an extra level of certainty that
the tests (and unit tests in particular) will not significantly diverge
from the code they are testing.

Makefile

@@ -27,7 +27,10 @@ mypy-host:
 mypy-container:
 	mypy $(MYPY_ARGS) container
 
-mypy: mypy-host  mypy-container ## check type hints with mypy
+mypy-tests:
+	mypy $(MYPY_ARGS) tests
+
+mypy: mypy-host  mypy-container mypy-tests ## check type hints with mypy
 
 .PHONY: lint
 lint: lint-black lint-isort mypy ## check the code with various linters

tests/__init__.py

@@ -3,7 +3,7 @@ from pathlib import Path
 
 import pytest
 
-sys.dangerzone_dev = True
+sys.dangerzone_dev = True  # type: ignore[attr-defined]
 
 SAMPLE_DIRECTORY = "test_docs"
 BASIC_SAMPLE = "sample.pdf"

tests/test_cli.py

@@ -11,7 +11,7 @@ from typing import Sequence
 
 import pytest
 from click.testing import CliRunner, Result
-from strip_ansi import strip_ansi  # type: ignore
+from strip_ansi import strip_ansi
 
 from dangerzone.cli import cli_main, display_banner
 
@@ -125,17 +125,17 @@ class TestCli(TestBase):
 
 
 class TestCliBasic(TestCli):
-    def test_no_args(self):
+    def test_no_args(self) -> None:
         """``$ dangerzone-cli``"""
         result = self.run_cli()
         result.assert_failure()
 
-    def test_help(self):
+    def test_help(self) -> None:
         """``$ dangerzone-cli --help``"""
         result = self.run_cli("--help")
         result.assert_success()
 
-    def test_display_banner(self, capfd):
+    def test_display_banner(self, capfd) -> None:  # type: ignore[no-untyped-def]
         display_banner()  # call the test subject
         (out, err) = capfd.readouterr()
         plain_lines = [strip_ansi(line) for line in out.splitlines()]
@@ -148,38 +148,38 @@ class TestCliBasic(TestCli):
 
 
 class TestCliConversion(TestCliBasic):
-    def test_invalid_lang(self):
+    def test_invalid_lang(self) -> None:
         result = self.run_cli([self.sample_doc, "--ocr-lang", "piglatin"])
         result.assert_failure()
 
     @for_each_doc
-    def test_formats(self, doc):
+    def test_formats(self, doc: Path) -> None:
         result = self.run_cli(str(doc))
         result.assert_success()
 
-    def test_output_filename(self):
+    def test_output_filename(self) -> None:
         temp_dir = tempfile.mkdtemp(prefix="dangerzone-")
         output_filename = str(Path(temp_dir) / "safe.pdf")
         result = self.run_cli([self.sample_doc, "--output-filename", output_filename])
         result.assert_success()
 
-    def test_output_filename_spaces(self):
+    def test_output_filename_spaces(self) -> None:
         temp_dir = tempfile.mkdtemp(prefix="dangerzone-")
         output_filename = str(Path(temp_dir) / "safe space.pdf")
         result = self.run_cli([self.sample_doc, "--output-filename", output_filename])
         result.assert_success()
 
-    def test_output_filename_new_dir(self):
+    def test_output_filename_new_dir(self) -> None:
         output_filename = str(Path("fake-directory") / "my-output.pdf")
         result = self.run_cli([self.sample_doc, "--output-filename", output_filename])
         result.assert_failure()
 
-    def test_sample_not_found(self):
+    def test_sample_not_found(self) -> None:
         input_filename = str(Path("fake-directory") / "fake-file.pdf")
         result = self.run_cli(input_filename)
         result.assert_failure()
 
-    def test_lang_eng(self):
+    def test_lang_eng(self) -> None:
         result = self.run_cli([self.sample_doc, "--ocr-lang", "eng"])
         result.assert_success()
 
@@ -191,7 +191,7 @@ class TestCliConversion(TestCliBasic):
             "spaces test.pdf",
         ],
     )
-    def test_filenames(self, filename):
+    def test_filenames(self, filename: str) -> None:
         tempdir = tempfile.mkdtemp(prefix="dangerzone-")
         doc_path = os.path.join(filename)
         shutil.copyfile(self.sample_doc, doc_path)

tests/test_util.py

@@ -9,7 +9,7 @@ import dangerzone.util as util
 VERSION_FILE_NAME = "version.txt"
 
 
-def test_get_resource_path():
+def test_get_resource_path() -> None:
     share_dir = Path("share").resolve()
     resource_path = Path(util.get_resource_path(VERSION_FILE_NAME)).parent
     assert share_dir.samefile(
@@ -18,6 +18,6 @@ def test_get_resource_path():
 
 
 @pytest.mark.skipif(platform.system() != "Windows", reason="Windows-specific")
-def test_get_subprocess_startupinfo():
+def test_get_subprocess_startupinfo() -> None:
     startupinfo = util.get_subprocess_startupinfo()
-    assert isinstance(startupinfo, subprocess.STARTUPINFO)
+    assert isinstance(startupinfo, subprocess.STARTUPINFO)  # type: ignore[attr-defined]