add mypy support

copier.yml

@@ -151,11 +151,11 @@ use_precommit:
   default: "{% if template_mode != 'minimal' %}yes{% else %}no{% endif %}"
   help: "Do you want to pre-commit hooks to format your code on save?"
 
-use_types:
+use_mypy:
   when: "{{ template_mode == 'custom' }}"
   type: bool
   default: "{% if template_mode != 'minimal' %}yes{% else %}no{% endif %}"
-  help: "Do you want to use typing annotations and type check your code?"
+  help: "Do you want to use mypy to check type annotations?"
 
 ############### All things related to testing ###################
 

includes/pyproject/deps-pep-621.toml.jinja

@@ -27,7 +27,7 @@ style = [
     "ruff",
 ]
 {% endif %}
-{%- if use_types -%}
+{%- if use_mypy -%}
 types = [
     "mypy",
 ]

pyproject.toml

@@ -35,6 +35,7 @@ ignore = [
     "S602",
     "S603",
     "S607",
+    "FBT001",  # boolean positional arguments are fine always but especially in tests
 ]
 
 [tool.ruff.lint.isort]

template/pyproject.toml.jinja

@@ -45,7 +45,7 @@ classifiers = [
     {% endif -%}
     "Operating System :: OS Independent",
     "Programming Language :: Python :: 3 :: Only",
-    {%- if use_types %}
+    {%- if use_mypy %}
     "Typing :: Typed",
     {%- endif %}
 ]
@@ -72,7 +72,7 @@ dev = [
         {%- if documentation!="" %}docs,{% endif -%}
         {%- if use_test %}tests,{% endif -%}
         {%- if use_lint %}style,{% endif -%}
-        {%- if use_types %}types,{% endif -%}
+        {%- if use_mypy %}types,{% endif -%}
     audit]",
     {%- endif %}
 ]
@@ -179,7 +179,7 @@ lines-after-imports = 1
 
 [tool.pydoclint]
 style = "numpy"
-{%- if use_types %}
+{%- if use_mypy %}
 arg-type-hints-in-signature = true
 {%- else  %}
 arg-type-hints-in-signature = false
@@ -192,24 +192,16 @@ exclude = "_version.py"
 {%- endif %}
 {%- endif %}
 
-{%- if use_types %}
-# TODO: Adjust mypy configuration.
-#[tool.mypy]
-#plugins = [
-#    "pydantic.mypy",
-#]
-
-# Stop mypy from complaining about missing types from imports.
-#[[tool.mypy.overrides]]
-#module = [
-#    "pandas",
-#]
-#ignore_missing_imports = true
-
-#[tool.pydantic-mypy]
-#init_forbid_extra = true
-#init_typed = true
-#warn_required_dynamic_aliases = true
+{%- if use_mypy %}
+[tool.mypy]
+packages = ["{{ package_name }}"]
+warn_redundant_casts = true
+warn_unused_ignores = true
+show_error_context = true
+show_column_numbers = true
+show_error_code_links = true
+pretty = true
+color_output = true
 {%- endif %}
 
 {%- if use_hatch_envs %}
@@ -242,7 +234,7 @@ extra-dependencies = [
 [tool.hatch.envs.audit.scripts]
 check = ["pip-audit"]
 
-{%- if use_types %}
+{%- if use_mypy %}
 [tool.hatch.envs.types]
 description = """Check the static types of the codebase."""
 dependencies = [

template/{% if use_git and dev_platform == 'GitHub' %}.github{% endif %}/workflows/test.yml.jinja

@@ -67,7 +67,7 @@ jobs:
     - name: Check dependencies
       run: hatch run audit:check
 
-{%- if use_types %}
+{%- if use_mypy %}
     - name: Check types
       run: hatch run types:check
 {%- endif %}
@@ -82,4 +82,27 @@ jobs:
       run: bash <(curl -s https://codecov.io/bash)
 {%- endraw %}
 {%- endif %}
+{%- else %}
+
+    - name: Install package
+      run: python -m pip install '.[dev]'
+
+    - name: Check dependencies
+      run: python -m pip-audit
+
+{%- if use_mypy %}
+
+    - name: Check types
+      run: python -m mypy
+{%- endif %}
+
+{%- if use_test %}
+
+    - name: Run tests
+      run: python -m pytest --cov={{ package_name }} --cov-report=term-missing
+
+    - name: Report coverage
+      shell: bash
+      run: bash <(curl -s https://codecov.io/bash)
+{%- endif %}
 {%- endif %}

tests/conftest.py

@@ -1,8 +1,9 @@
 """Provide fixtures to the entire test suite."""
 
 import shutil
+from collections.abc import Generator
 from pathlib import Path
-from typing import TYPE_CHECKING, Generator
+from typing import TYPE_CHECKING
 
 import pytest
 from _pytest.monkeypatch import MonkeyPatch

tests/test_template_init.py

@@ -22,8 +22,10 @@
 import os
 import subprocess
 import sys
+import venv
 from datetime import datetime, timezone
 from pathlib import Path
+from textwrap import dedent
 from typing import Callable
 
 import pytest
@@ -196,7 +198,7 @@ def test_docs_build(documentation: str, generated: Callable[..., Path], use_hatc
             )
         run_command("sphinx-apidoc -o docs/api src/alien_clones", project)
         # prepend pythonpath so we don't have to actually install here...
-        run_command(f"PYTHONPATH={str(project/'src')} sphinx-build -W -b html docs docs/_build", project)
+        run_command(f"PYTHONPATH={project/'src'!s} sphinx-build -W -b html docs docs/_build", project)
 
     run_command("pre-commit run --all-files -v check-readthedocs", project)
 
@@ -229,7 +231,7 @@ def test_non_hatch_deps(
     project = generated(
         use_hatch_envs=False,
         use_lint=True,
-        use_types=True,
+        use_mypy=True,
         use_test=True,
         use_git=False,
         documentation=documentation,
@@ -254,3 +256,50 @@ def test_non_hatch_deps(
     if documentation != "no":
         assert "docs" in optional_deps
         assert any(dep.startswith(documentation) for dep in optional_deps["docs"])
+
+@pytest.mark.parametrize("use_hatch_envs", [True, False])
+@pytest.mark.parametrize("valid", [True, False])
+def test_mypy(generated: Callable[..., Path], use_hatch_envs: bool, valid: bool, tmp_path: Path):
+    """Mypy type checking works out of the box."""
+    if valid:
+        module = dedent("""
+        def f1(value: int, other: int = 2) -> int:
+            return value * other
+
+        def f2(value: int) -> float:
+            return f1(value, 5) / 2
+        """)
+    else:
+        module = dedent("""
+        def f1(value: int, other: int = 2) -> int:
+            return value * other
+
+        def f2(value: str) -> str:
+            return f1(value, 5) / 2
+        """)
+
+    root = generated(use_hatch_envs=use_hatch_envs, use_mypy=True)
+    pkg_path = root / "src" / "alien_clones"
+    module_path = pkg_path / "typechecking.py"
+    with module_path.open("w") as f:
+        f.write(module)
+
+    if use_hatch_envs:
+        command = "hatch run types:check"
+    else:
+        venv_path = tmp_path / ".venv"
+        if sys.platform == "win32":
+            mypy_path = venv_path / "Scripts" / "mypy.exe"
+            python_path = venv_path / "Scripts" / "python.exe"
+        else:
+            mypy_path = venv_path / "bin" / "mypy"
+            python_path = venv_path / "bin" / "python"
+        venv.EnvBuilder(with_pip=True).create(venv_path)
+        run_command(f'{python_path!s} -m pip install -e ".[types]"', root)
+        command = f"{mypy_path!s} {pkg_path!s}"
+
+    if valid:
+        run_command(command, root)
+    else:
+        with pytest.raises(subprocess.CalledProcessError):
+            run_command(command, root)