Added stubgen+mypy test

Author: timohl

tests/requirements.txt

@@ -1,6 +1,7 @@
 --extra-index-url=https://www.graalvm.org/python/wheels
 --only-binary=:all:
 build>=1
+mypy
 numpy~=1.23.0; python_version=="3.8" and platform_python_implementation=="PyPy"
 numpy~=1.25.0; python_version=="3.9" and platform_python_implementation=="PyPy"
 numpy~=2.2.0; python_version=="3.10" and platform_python_implementation=="PyPy"

tests/test_stubgen.py

@@ -1,7 +1,35 @@
 from __future__ import annotations
 
+from pathlib import Path
+
+import pybind11_stubgen as stubgen
+from mypy import api
+
 from pybind11_tests import stubgen as m
 
 
-def test_stubgen() -> None:
+def test_stubgen(tmp_path: Path) -> None:
     assert m.add_int(1, 2) == 3
+
+    stubgen.main(
+        [
+            "pybind11_tests.stubgen",
+            "-o",
+            tmp_path.as_posix(),
+        ]
+    )
+    print(f"Stubgen output: {tmp_path.as_posix()}")
+    stub_file = tmp_path / "pybind11_tests" / "stubgen.pyi"
+    assert stub_file.exists()
+    stub_content = stub_file.read_text()
+    assert (
+        "def add_int(a: typing.SupportsInt, b: typing.SupportsInt) -> int:"
+        in stub_content
+    )
+    normal_report, error_report, exit_status = api.run([stub_file.as_posix()])
+    print("Normal report:")
+    print(normal_report)
+    print("Error report:")
+    print(error_report)
+    assert exit_status == 0
+    assert "Success: no issues found in 1 source file" in normal_report