Merge pull request #77 from cdunklau/fix-async-fixture-docs

Correct and clarify async fixture docs

Author: altendky

README.rst

@@ -111,10 +111,25 @@ async/await fixtures
 pytest fixture semantics of setup, value, and teardown.  At present only
 function scope is supported.
 
+Note: You must *call* ``pytest_twisted.async_fixture()`` and
+``pytest_twisted.async_yield_fixture()``.
+This requirement may be removed in a future release.
+
 .. code-block:: python
 
-  @pytest_twisted.async_fixture
+  # No yield (coroutine function)
+  #   -> use pytest_twisted.async_fixture()
+  @pytest_twisted.async_fixture()
   async def foo():
+      d = defer.Deferred()
+      reactor.callLater(0.01, d.callback, 42)
+      value = await d
+      return value
+
+  # With yield (asynchronous generator)
+  #   -> use pytest_twisted.async_yield_fixture()
+  @pytest_twisted.async_yield_fixture()
+  async def foo_with_teardown():
       d1, d2 = defer.Deferred(), defer.Deferred()
       reactor.callLater(0.01, d1.callback, 42)
       reactor.callLater(0.02, d2.callback, 37)

pytest_twisted.py

@@ -35,7 +35,7 @@ class AsyncFixtureUnsupportedScopeError(Exception):
     @classmethod
     def from_scope(cls, scope):
         return cls(
-            'Unsupported scope used for async fixture: {}'.format(scope)
+            'Unsupported scope {0!r} used for async fixture'.format(scope)
         )