Async fixtures in progress.

Author: Tinche

pytest_asyncio/__init__.py

@@ -1 +1,4 @@
+"""The main point for importing pytest-asyncio items."""
 __version__ = '0.5.0'
+
+from .plugin import async_fixture

pytest_asyncio/plugin.py

@@ -1,5 +1,6 @@
 """pytest-asyncio implementation."""
 import asyncio
+import functools
 import inspect
 import socket
 
@@ -8,9 +9,11 @@
 
 import pytest
 
+from _pytest.fixtures import FixtureFunctionMarker
 from _pytest.python import transfer_markers
 
 
+
 class ForbiddenEventLoopPolicy(asyncio.DefaultEventLoopPolicy):
     """An event loop policy that raises errors on most operations.
 
@@ -148,6 +151,7 @@ def unused_tcp_port_factory():
     produced = set()
 
     def factory():
+        """Return an unused port."""
         port = unused_tcp_port()
 
         while port in produced:
@@ -157,3 +161,34 @@ def factory():
 
         return port
     return factory
+
+
+class AsyncFixtureFunctionMarker(FixtureFunctionMarker):
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+    def __call__(self, coroutine):
+        """The parameter is the actual fixture coroutine."""
+        if not _is_coroutine(coroutine):
+            raise ValueError('Only coroutine functions supported')
+
+        @functools.wraps(coroutine)
+        def inner(*args, **kwargs):
+            loop = None
+            return loop.run_until_complete(coroutine(*args, **kwargs))
+
+        inner._pytestfixturefunction = self
+        return inner
+
+
+def async_fixture(scope='function', params=None, autouse=False, ids=None):
+    if callable(scope) and params is None and not autouse:
+        # direct invocation
+        marker = AsyncFixtureFunctionMarker(
+            'function', params, autouse)
+        return marker(scope)
+    if params is not None and not isinstance(params, (list, tuple)):
+        params = list(params)
+    return AsyncFixtureFunctionMarker(
+        scope, params, autouse, ids=ids)

tests/test_async_fixtures.py

@@ -0,0 +1,25 @@
+"""Tests for async fixtures."""
+import asyncio
+
+import pytest
+from pytest_asyncio import async_fixture
+
+@pytest.fixture
+def shared_state():
+    """Some shared state, so we can assert the order of operations."""
+    return {}
+
+
+@async_fixture
+def minimal_async_fixture(shared_state):
+    """A minimal asyncio fixture."""
+    shared_state['async_fixture'] = 1
+    yield from asyncio.sleep(0.01)
+    shared_state['async_fixture'] += 1
+
+
+@pytest.mark.asyncio
+def test_minimal_asynx_fixture(shared_state, minimal_async_fixture):
+    """Test minimal async fixture working."""
+    assert shared_state['async_fixture'] == 2
+    yield from asyncio.sleep(0)