fix #912 - ensure mypy safe version template

this also adds

* a regression test running mypy (unpinned)
* a regression tests running flake8 (unpinned)

CHANGELOG.rst

@@ -1,3 +1,11 @@
+v8.0.2
+======
+
+bugfix
+------
+
+* fix #912: ensure mypy safety of the version template + regression test
+
 
 v8.0.1
 ======

src/setuptools_scm/_integration/dump_version.py

@@ -15,6 +15,8 @@
     ".py": """\
 # file generated by setuptools_scm
 # don't change, don't track in version control
+from __future__ import annotations
+
 __version__ = version = {version!r}  # type: str
 __version_tuple__ = version_tuple = {version_tuple!r}  # type: tuple[int | str, ...]
 """,

testing/test_functions.py

@@ -110,24 +110,44 @@ def test_dump_version_modern(monkeypatch: pytest.MonkeyPatch, tmp_path: Path) ->
     assert target.read_text() == version
 
 
-def test_dump_version_on_old_python(tmp_path: Path) -> None:
-    python37 = shutil.which("python3.7")
-    if python37 is None:
-        pytest.skip("python3.7 not found")
+def dump_a_version(tmp_path: Path) -> None:
     from setuptools_scm._integration.dump_version import write_version_to_path
 
     version = "1.2.3"
     scm_version = meta(version, config=c)
     write_version_to_path(
         tmp_path / "VERSION.py", template=None, version=version, scm_version=scm_version
     )
+
+
+def test_dump_version_on_old_python(tmp_path: Path) -> None:
+    python37 = shutil.which("python3.7")
+    if python37 is None:
+        pytest.skip("python3.7 not found")
+    dump_a_version(tmp_path)
     subprocess.run(
         [python37, "-c", "import VERSION;print(VERSION.version)"],
         cwd=tmp_path,
         check=True,
     )
 
 
+def test_dump_version_mypy(tmp_path: Path) -> None:
+    mypy = shutil.which("mypy")
+    if mypy is None:
+        pytest.skip("mypy not found")
+    dump_a_version(tmp_path)
+    subprocess.run([mypy, "--strict", "VERSION.py"], cwd=tmp_path, check=True)
+
+
+def test_dump_version_flake8(tmp_path: Path) -> None:
+    flake8 = shutil.which("flake8")
+    if flake8 is None:
+        pytest.skip("flake8 not found")
+    dump_a_version(tmp_path)
+    subprocess.run([flake8, "VERSION.py"], cwd=tmp_path, check=True)
+
+
 def test_has_command() -> None:
     with pytest.warns(RuntimeWarning, match="yadayada"):
         assert not has_command("yadayada_setuptools_aint_ne")