Preliminary cli for mypy options

MANIFEST.in

@@ -5,3 +5,4 @@ include README*
 include SECURITY*
 include pytest.ini
 recursive-include qtpy/tests *.py *.ui
+include qtpy/py.typed

README.md

@@ -71,6 +71,25 @@ conda install qtpy
 ```
 
 
+### mypy
+
+A CLI is offered to help with usage of QtPy.  Presently, the only feature
+is to generate command line arguments for Mypy that will enable it to
+process the QtPy source files with the same API as QtPy itself would have
+selected.
+
+```
+--always-false=PYQT5 --always-false=PYQT6 --always-true=PYSIDE2 --always-false=PYSIDE6
+```
+
+If using bash or similar, this can be integrated into the Mypy command line
+as follows.
+
+```console
+$ env/bin/mypy --package mypackage $(env/bin/qtpy mypy-args)
+```
+
+
 ## Contributing
 
 Everyone is welcome to contribute!

qtpy/__init__.py

@@ -101,9 +101,11 @@ class PythonQtWarning(Warning):
 # Setting a default value for QT_API
 os.environ.setdefault(QT_API, 'pyqt5')
 
+API_NAMES = {'pyqt5': 'PyQt5', 'pyqt6': 'PyQt6',
+             'pyside2':'PySide2', 'pyside6': 'PySide6'}
 API = os.environ[QT_API].lower()
 initial_api = API
-assert API in (PYQT5_API + PYQT6_API + PYSIDE2_API + PYSIDE6_API)
+assert API in API_NAMES
 
 is_old_pyqt = is_pyqt46 = False
 QT5 = PYQT5 = True
@@ -201,8 +203,9 @@ class PythonQtWarning(Warning):
     warnings.warn('Selected binding "{}" could not be found, '
                   'using "{}"'.format(initial_api, API), RuntimeWarning)
 
-API_NAME = {'pyqt6': 'PyQt6', 'pyqt5': 'PyQt5',
-            'pyside2':'PySide2', 'pyside6': 'PySide6'}[API]
+
+# Set display name of the Qt API
+API_NAME = API_NAMES[API]
 
 try:
     # QtDataVisualization backward compatibility (QtDataVisualization vs. QtDatavisualization)

qtpy/__main__.py

@@ -0,0 +1,9 @@
+import qtpy.cli
+
+
+def main():
+    return qtpy.cli.cli()
+
+
+if __name__ == "__main__":
+    main()

qtpy/cli.py

@@ -0,0 +1,77 @@
+# -*- coding: utf-8 -*-
+# -----------------------------------------------------------------------------
+# Copyright © 2009- The QtPy Contributors
+#
+# Released under the terms of the MIT License
+# (see LICENSE.txt for details)
+# -----------------------------------------------------------------------------
+
+"""Provide a CLI to allow configuring developer settings, including mypy."""
+
+# Standard library imports
+import argparse
+import sys
+import textwrap
+
+
+class RawDescriptionArgumentDefaultsHelpFormatter(
+    argparse.RawDescriptionHelpFormatter,
+    argparse.ArgumentDefaultsHelpFormatter,
+):
+    pass
+
+
+def cli(args=sys.argv[1:]):
+    parser = argparse.ArgumentParser(
+        description="Features in support of development with QtPy.",
+        formatter_class=RawDescriptionArgumentDefaultsHelpFormatter,
+    )
+
+    parser.set_defaults(func=parser.print_help)
+
+    cli_subparsers = parser.add_subparsers()
+
+    mypy_args_parser = cli_subparsers.add_parser(
+        name='mypy-args',
+        description=textwrap.dedent(
+            """\
+            Generate command line arguments for using mypy with QtPy.
+
+            This will generate strings similar to the following which help guide mypy
+            through which library QtPy would have used so that mypy can get the proper
+            underlying type hints.
+
+                --always-false=PYQT5 --always-false=PYQT6 --always-true=PYSIDE2 --always-false=PYSIDE6
+
+            Use such as:
+
+                env/bin/mypy --package mypackage $(env/bin/qtpy mypy-args)
+            """
+        ),
+        formatter_class=RawDescriptionArgumentDefaultsHelpFormatter,
+    )
+    mypy_args_parser.set_defaults(func=mypy_args)
+
+    arguments = parser.parse_args(args=args)
+
+    reserved_parameters = {'func'}
+    cleaned = {
+        k: v
+        for k, v in vars(arguments).items()
+        if k not in reserved_parameters
+    }
+
+    arguments.func(**cleaned)
+
+
+def mypy_args():
+    options = {False: '--always-false', True: '--always-true'}
+
+    import qtpy
+
+    apis_active = {name: qtpy.API == name for name in qtpy.API_NAMES}
+    print(' '.join(
+        f'{options[is_active]}={name.upper()}'
+        for name, is_active
+        in apis_active.items()
+    ))

qtpy/tests/test_cli.py

@@ -0,0 +1,45 @@
+from __future__ import absolute_import
+
+import subprocess
+import sys
+
+import pytest
+
+import qtpy
+
+
+subcommands = [
+    ['mypy'],
+    ['mypy', 'args'],
+]
+
+
+@pytest.mark.parametrize(
+    argnames=['subcommand'],
+    argvalues=[[subcommand] for subcommand in subcommands],
+    ids=[' '.join(subcommand) for subcommand in subcommands],
+)
+def test_cli_help_does_not_fail(subcommand):
+    # .check_call() over .run(..., check=True) because of py2
+    subprocess.check_call(
+        [sys.executable, '-m', 'qtpy', *subcommand, '--help'],
+    )
+
+
+def test_cli_mypy_args():
+    output = subprocess.check_output(
+        [sys.executable, '-m', 'qtpy', 'mypy', 'args'],
+    )
+
+    if qtpy.PYQT5:
+        expected = b'--always-true=PYQT5 --always-false=PYQT6 --always-false=PYSIDE2 --always-false=PYSIDE6\n'
+    elif qtpy.PYQT6:
+        expected = b'--always-false=PYQT5 --always-true=PYQT6 --always-false=PYSIDE2 --always-false=PYSIDE6\n'
+    elif qtpy.PYSIDE2:
+        expected = b'--always-false=PYQT5 --always-false=PYQT6 --always-true=PYSIDE2 --always-false=PYSIDE6\n'
+    elif qtpy.PYSIDE6:
+        expected = b'--always-false=PYQT5 --always-false=PYQT6 --always-false=PYSIDE2 --always-true=PYSIDE6\n'
+    else:
+        assert False, 'No valid API to test'
+
+    assert output == expected

setup.cfg

@@ -56,3 +56,7 @@ test =
     pytest>=6,!=7.0.0,!=7.0.1
     pytest-cov>=3.0.0
     pytest-qt
+
+[options.entry_points]
+console_scripts =
+    qtpy = qtpy.__main__:main