Run static type checking with Mypy

.github/workflows/test.yml

@@ -45,6 +45,8 @@ jobs:
           "ubuntu-py310",
           "ubuntu-py311",
           "ubuntu-py312",
+
+          "ubuntu-mypy",
         ]
 
         include:
@@ -99,6 +101,11 @@ jobs:
             os: ubuntu-latest
             tox_env: "py312"
 
+          - name: "ubuntu-mypy"
+            python: "3.12"
+            os: ubuntu-latest
+            tox_env: "mypy"
+
     steps:
     - uses: actions/checkout@v3
 

pyproject.toml

@@ -5,4 +5,8 @@ requires = [
 ]
 build-backend = "setuptools.build_meta"
 
+[tool.mypy]
+warn_unused_configs = true
+warn_unused_ignores = true
+
 [tool.setuptools_scm]

setup.cfg

@@ -26,17 +26,24 @@ classifiers =
 keywords = test, unittest, pytest
 
 [options]
-py_modules = pytest_subtests
 install_requires =
     pytest>=7.0
     attrs>=19.2.0
 python_requires = >=3.7
+packages = find:
 package_dir =
-    =src
+    = src
 setup_requires =
     setuptools
     setuptools-scm>=6.0
 
+[options.packages.find]
+where = src
+
 [options.entry_points]
 pytest11 =
-    subtests = pytest_subtests
+    subtests = pytest_subtests.plugin
+
+# Include src/py.typed in the distribution.
+[options.package_data]
+pytest_subtests = py.typed

src/pytest_subtests.py → src/pytest_subtests/plugin.py

@@ -1,6 +1,10 @@
+from __future__ import annotations
+
 import time
 from contextlib import contextmanager
 from contextlib import nullcontext
+from typing import Any
+from typing import Mapping
 
 import attr
 import pytest
@@ -17,7 +21,7 @@
 from _pytest.unittest import TestCaseFunction
 
 
-def pytest_addoption(parser):
+def pytest_addoption(parser: pytest.Parser) -> None:
     group = parser.getgroup("subtests")
     group.addoption(
         "--no-subtests-shortletter",
@@ -35,15 +39,15 @@ class SubTestContext:
 
 
 @attr.s(init=False)
-class SubTestReport(TestReport):
+class SubTestReport(TestReport):  # type: ignore[misc]
     context = attr.ib()
 
     @property
-    def head_line(self):
+    def head_line(self) -> str:
         _, _, domain = self.location
         return f"{domain} {self.sub_test_description()}"
 
-    def sub_test_description(self):
+    def sub_test_description(self) -> str:
         parts = []
         if isinstance(self.context.msg, str):
             parts.append(f"[{self.context.msg}]")
@@ -54,7 +58,7 @@ def sub_test_description(self):
             parts.append(f"({params_desc})")
         return " ".join(parts) or "(<subtest>)"
 
-    def _to_json(self):
+    def _to_json(self) -> dict:
         data = super()._to_json()
         del data["context"]
         data["_report_type"] = "SubTestReport"
@@ -95,9 +99,9 @@ def _addSubTest(self, test_case, test, exc_info):
             )
 
 
-def pytest_configure(config):
-    TestCaseFunction.addSubTest = _addSubTest
-    TestCaseFunction.failfast = False
+def pytest_configure(config: pytest.Config) -> None:
+    TestCaseFunction.addSubTest = _addSubTest  # type: ignore[attr-defined]
+    TestCaseFunction.failfast = False  # type: ignore[attr-defined]
 
     # Hack (#86): the terminal does not know about the "subtests"
     # status, so it will by default turn the output to yellow.
@@ -110,7 +114,7 @@ def pytest_configure(config):
     # We need to check if we are not re-adding because we run our own tests
     # with pytester in-process mode, so this will be called multiple times.
     if new_types[0] not in _pytest.terminal.KNOWN_TYPES:
-        _pytest.terminal.KNOWN_TYPES = _pytest.terminal.KNOWN_TYPES + new_types
+        _pytest.terminal.KNOWN_TYPES = _pytest.terminal.KNOWN_TYPES + new_types  # type: ignore[assignment]
 
     _pytest.terminal._color_for_type.update(
         {
@@ -121,7 +125,7 @@ def pytest_configure(config):
     )
 
 
-def pytest_unconfigure():
+def pytest_unconfigure() -> None:
     if hasattr(TestCaseFunction, "addSubTest"):
         del TestCaseFunction.addSubTest
     if hasattr(TestCaseFunction, "failfast"):
@@ -193,7 +197,7 @@ def _capturing_logs(self):
                 yield captured_logs
 
     @contextmanager
-    def test(self, msg=None, **kwargs):
+    def test(self, msg: str | None = None, **kwargs):
         start = time.time()
         precise_start = time.perf_counter()
         exc_info = None
@@ -257,7 +261,7 @@ class Captured:
     out = attr.ib(default="", type=str)
     err = attr.ib(default="", type=str)
 
-    def update_report(self, report):
+    def update_report(self, report: pytest.TestReport):
         if self.out:
             report.sections.append(("Captured stdout call", self.out))
         if self.err:
@@ -282,15 +286,19 @@ def pytest_report_to_serializable(report):
         return report._to_json()
 
 
-def pytest_report_from_serializable(data):
+def pytest_report_from_serializable(data: dict[str, Any]):
     if data.get("_report_type") == "SubTestReport":
         return SubTestReport._from_json(data)
+    return None
 
 
 @pytest.hookimpl(tryfirst=True)
-def pytest_report_teststatus(report, config):
+def pytest_report_teststatus(
+    report: pytest.TestReport,
+    config: pytest.Config,
+) -> tuple[str, str, str | Mapping[str, bool]] | None:
     if report.when != "call" or not isinstance(report, SubTestReport):
-        return
+        return None
 
     if hasattr(report, "wasxfail"):
         return None
@@ -306,3 +314,5 @@ def pytest_report_teststatus(report, config):
     elif outcome == "failed":
         short = "" if config.option.no_subtests_shortletter else "u"
         return outcome, short, f"{description} SUBFAIL"
+
+    return None

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py37,py38,py39,py310,py311,py312
+envlist = py37,py38,py39,py310,py311,py312,mypy
 
 [testenv]
 passenv =
@@ -12,3 +12,7 @@ deps =
 
 commands =
     pytest {posargs:tests}
+
+[testenv:mypy]
+deps = mypy
+commands = mypy src