libs: Add mypy-abstracts plugin (#24)

Signed-off-by: Ryan Northey <ryan@synca.io>

mypy-abstracts/README.rst

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+
+mypy-abstracts
+==============
+
+mypy plugin to recognize classes decorated with ``abstracts.implementer``.

mypy-abstracts/VERSION

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+0.0.1

mypy-abstracts/mypy_abstracts/plugin.py

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+from mypy.plugin import Plugin
+from mypy.nodes import SymbolTable, TypeInfo
+from mypy.types import Instance
+
+
+class AbstractionPlugin(Plugin):
+
+    def get_class_decorator_hook(self, fullname: str):
+
+        def _decorator_hook(*la):
+            impl = la[0].cls.info
+            iface = la[0].reason.args[0].node
+            try:
+                promote = Instance(iface, [])
+            except TypeError:
+                return
+            if not any(ti._promote == promote for ti in impl.mro):
+                faketi = TypeInfo(SymbolTable(), iface.defn, iface.module_name)
+                faketi._promote = promote
+                impl.mro.append(faketi)
+
+        if fullname == "abstracts.decorators.implementer":
+            return _decorator_hook
+
+
+def plugin(version: str):
+    # ignore version argument if the plugin works with all mypy versions.
+    return AbstractionPlugin

mypy-abstracts/setup.py

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+#!/usr/bin/env python
+
+import os
+import codecs
+from setuptools import setup  # type:ignore
+
+
+DESCRIPTION = (
+    "A patches test fixture which provides a contextmanager for handling "
+    "multiple mock patches")
+
+
+def read(fname):
+    file_path = os.path.join(os.path.dirname(__file__), fname)
+    return codecs.open(file_path, encoding='utf-8').read()
+
+
+setup(
+    name='mypy-abstracts',
+    version=read("VERSION"),
+    author='Ryan Northey',
+    author_email='ryan@synca.io',
+    maintainer='Ryan Northey',
+    maintainer_email='ryan@synca.io',
+    license='Apache Software License 2.0',
+    url='https://github.com/envoyproxy/pytooling/mypy-abstracts',
+    description=DESCRIPTION,
+    long_description=read('README.rst'),
+    py_modules=['mypy_abstracts'],
+    python_requires='>=3.5',
+    install_requires=['mypy'],
+    extras_require={
+        "test": [
+            "pytest",
+            "pytest-coverage"],
+        "lint": ['flake8'],
+        "publish": ['wheel'],
+    },
+    classifiers=[
+        'Development Status :: 4 - Beta',
+        'Framework :: Pytest',
+        'Intended Audience :: Developers',
+        'Topic :: Software Development :: Testing',
+        'Programming Language :: Python',
+        'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
+        'Programming Language :: Python :: 3 :: Only',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Operating System :: OS Independent',
+        'License :: OSI Approved :: Apache Software License',
+    ],
+    entry_points={
+        'pytest11': [
+            'patches = pytest_patches',
+        ],
+    },
+)