Support async tests which use Hypothesis

.gitignore

@@ -22,6 +22,7 @@ var/
 *.egg-info/
 .installed.cfg
 *.egg
+.hypothesis/
 
 # PyInstaller
 #  Usually these files are written by a python script from a template

README.rst

@@ -178,6 +178,9 @@ Changelog
 
 0.10.0. (UNRELEASED)
 ~~~~~~~~~~~~~~~~~~~~
+- ``pytest-asyncio`` integrates with `Hypothesis <https://hypothesis.readthedocs.io>`_
+  to support ``@given`` on async test functions using ``asyncio``.
+  `#102` <https://github.com/pytest-dev/pytest-asyncio/pull/102>
 
 0.9.0 (2018-07-28)
 ~~~~~~~~~~~~~~~~~~

pytest_asyncio/plugin.py

@@ -1,6 +1,7 @@
 """pytest-asyncio implementation."""
 import asyncio
 import contextlib
+import functools
 import inspect
 import socket
 
@@ -139,7 +140,8 @@ def pytest_pyfunc_call(pyfuncitem):
     function call.
     """
     for marker_name, fixture_name in _markers_2_fixtures.items():
-        if marker_name in pyfuncitem.keywords:
+        if marker_name in pyfuncitem.keywords \
+                and not getattr(pyfuncitem.obj, 'is_hypothesis_test', False):
             event_loop = pyfuncitem.funcargs[fixture_name]
 
             funcargs = pyfuncitem.funcargs
@@ -152,11 +154,39 @@ def pytest_pyfunc_call(pyfuncitem):
             return True
 
 
+def wrap_in_sync(func):
+    """Return a sync wrapper around an async function."""
+
+    @functools.wraps(func)
+    def inner(**kwargs):
+        loop = asyncio.get_event_loop_policy().new_event_loop()
+        try:
+            coro = func(**kwargs)
+            if coro is not None:
+                future = asyncio.ensure_future(coro, loop=loop)
+                loop.run_until_complete(future)
+        finally:
+            loop.close()
+
+    return inner
+
+
 def pytest_runtest_setup(item):
     for marker, fixture in _markers_2_fixtures.items():
         if marker in item.keywords and fixture not in item.fixturenames:
             # inject an event loop fixture for all async tests
             item.fixturenames.append(fixture)
+    if item.get_closest_marker("asyncio") is not None:
+        if hasattr(item.obj, 'hypothesis'):
+            # If it's a Hypothesis test, we insert the wrap_in_sync decorator
+            item.obj.hypothesis.inner_test = wrap_in_sync(
+                item.obj.hypothesis.inner_test
+            )
+        elif getattr(item.obj, 'is_hypothesis_test', False):
+            pytest.fail(
+                'test function `%r` is using Hypothesis, but pytest-asyncio '
+                'only works with Hypothesis 3.64.0 or later.' % item
+            )
 
 
 # maps marker to the name of the event loop fixture that will be available

setup.py

@@ -43,7 +43,11 @@ def find_version():
     install_requires=["pytest >= 3.0.6"],
     extras_require={
         ':python_version == "3.5"': "async_generator >= 1.3",
-        "testing": ["coverage", "async_generator >= 1.3"],
+        "testing": [
+            "coverage",
+            "async_generator >= 1.3",
+            "hypothesis >= 3.64",
+        ],
     },
     entry_points={"pytest11": ["asyncio = pytest_asyncio.plugin"]},
 )

tests/test_hypothesis_integration.py

@@ -0,0 +1,27 @@
+"""Tests for the Hypothesis integration, which wraps async functions in a
+sync shim for Hypothesis.
+"""
+
+import pytest
+
+from hypothesis import given, strategies as st
+
+
+@given(st.integers())
+@pytest.mark.asyncio
+async def test_mark_inner(n):
+    assert isinstance(n, int)
+
+
+@pytest.mark.asyncio
+@given(st.integers())
+async def test_mark_outer(n):
+    assert isinstance(n, int)
+
+
+@pytest.mark.parametrize("y", [1, 2])
+@given(x=st.none())
+@pytest.mark.asyncio
+async def test_mark_and_parametrize(x, y):
+    assert x is None
+    assert y in (1, 2)