tests/test_typing.py: new, check that mypy finds py.typed file in pymupdf install.

Author: julian-smith-artifex-com

tests/test_typing.py

@@ -0,0 +1,33 @@
+import os
+import subprocess
+
+import pymupdf
+
+
+def run(command, check=1):
+    print(f'Running: {command}')
+    subprocess.run(command, shell=1, check=check)
+
+def test_py_typed():
+    print(f'test_py_typed(): {pymupdf.__path__=}')
+    run('pip uninstall -y mypy')
+    run('pip install mypy')
+    root = os.path.abspath(f'{__file__}/../..')
+    
+    # Run mypy on this .py file; it will fail at `import pymypdf` if the
+    # pymupdf install does not have a py.typed file.
+    #
+    # This doesn't actually check pymupdf's typing. It looks like
+    # we can do that with `mypy -m pymupdf`, but as of 2026-1-18 this
+    # gives many errors such as:
+    #
+    #   ...site-packages/pymupdf/__init__.py:15346: error: point_like? has no attribute "y"  [attr-defined]
+    #
+    # It's important to use `--no-incremental`, otherwise if one has
+    # experimented with `mypy -m pymupdf`, this test will get the
+    # same failures, via `.mypy_cache/` directories.
+    #
+    # We run in sub-directory to avoid spurious mypy errors
+    # if there is a local mupdf/ directory.
+    #
+    run(f'cd {root}/tests && mypy --no-incremental {os.path.abspath(__file__)}')