create a "tests" key in extras_require

.appveyor.yml

@@ -39,15 +39,12 @@ install:
   - python --version
   - python -m pip install --upgrade pip
   - python -m pip install --upgrade setuptools wheel
-  - python -m pip install --upgrade pytest pytest-cov pytest-runner
   - python -m pip install %QT_API%
   - IF "%CLONE_PYTHONNET%"=="true" (
       python -m pip install --upgrade pycparser &&
       python -m pip install git+https://github.com/pythonnet/pythonnet.git
-    ) ELSE (
-      python -m pip install --upgrade pythonnet
     )
-  - python -m pip list
+  - python -m pip install --upgrade --editable .[tests]
 
 build: off
 

.travis.yml

@@ -72,9 +72,8 @@ install:
   - python --version
   - python -m pip install --upgrade pip
   - python -m pip install --upgrade setuptools wheel
-  - python -m pip install --upgrade pytest pytest-cov pytest-runner
   - python -m pip install --upgrade $QT_API
-  - python -m pip list
+  - python -m pip install --upgrade --editable .[tests]
 
 before_script:
   - |

setup.py

@@ -134,14 +134,11 @@ def get_version():
 
 install_requires = []
 
-tests_require = ['pytest', 'pytest-cov']
-if sys.version_info[:2] == (3, 5):
-    tests_require.append('PySide2')
-else:
-    tests_require.append('PySide6')
-
-if sys.platform == 'win32' and sys.version_info[:2] < (3, 9):
-    tests_require.append('pythonnet')
+tests_require = [
+    'pytest',
+    'pytest-cov',
+    "pythonnet;sys_platform=='win32' and python_version<'3.9'",
+]
 
 testing = {'test', 'tests', 'pytest'}.intersection(sys.argv)
 pytest_runner = ['pytest-runner'] if testing else []
@@ -184,6 +181,7 @@ def get_version():
         'PySide2': ['PySide2'],
         'PyQt6': ['PyQt6'],
         'PyQt5': ['PyQt5'],
+        'tests': tests_require,
     },
     cmdclass={'docs': BuildDocs, 'apidocs': ApiDocs},
     packages=find_packages(include=('msl*',)),