Only function scope supported for async fixtures

Author: altendky

README.rst

@@ -88,7 +88,8 @@ Waiting for deferreds in fixtures
 async/await fixtures
 ====================
 ``async``/``await`` fixtures can be used along with ``yield`` for normal
-pytest fixture semantics of setup, value, and teardown.
+pytest fixture semantics of setup, value, and teardown.  At present only
+function scope is supported.
 
   @pytest_twisted.async_fixture
   async def foo():

pytest_twisted.py

@@ -30,6 +30,14 @@ def from_generator(cls, generator):
         )
 
 
+class AsyncFixtureUnsupportedScopeError(Exception):
+    @classmethod
+    def from_scope(cls, scope):
+        return cls(
+            'Unsupported scope used for async fixture: {}'.format(scope)
+        )
+
+
 class _config:
     external_reactor = False
 
@@ -110,6 +118,14 @@ def __init__(self, coroutine, mark):
 def _marked_async_fixture(mark):
     @functools.wraps(pytest.fixture)
     def fixture(*args, **kwargs):
+        try:
+            scope = args[0]
+        except IndexError:
+            scope = kwargs.get('scope', 'function')
+
+        if scope != 'function':
+            raise AsyncFixtureUnsupportedScopeError.from_scope(scope=scope)
+
         def marker(f):
             @functools.wraps(f)
             def w(*args, **kwargs):
@@ -159,7 +175,7 @@ def _pytest_pyfunc_call(pyfuncitem):
                         )
                     else:
                         raise UnrecognizedCoroutineMarkError.from_mark(
-                            wrapper.mark,
+                            mark=wrapper.mark,
                         )
                 else:
                     arg_value = funcargs[arg]

testing/test_basic.py

@@ -345,6 +345,54 @@ def test_succeed(foo):
     assert_outcomes(rr, {"passed": 2, "failed": 3})
 
 
+@skip_if_no_async_generators()
+def test_async_fixture_function_scope(testdir, cmd_opts):
+    test_file = """
+    from twisted.internet import reactor, defer
+    import pytest
+    import pytest_twisted
+
+    check_me = 0
+
+    @pytest_twisted.async_yield_fixture(scope="function")
+    async def foo():
+        global check_me
+
+        if check_me != 0:
+            raise Exception('check_me already modified before fixture run')
+
+        check_me = 1
+
+        yield 42
+
+        if check_me != 2:
+            raise Exception(
+                'check_me not updated properly: {}'.format(check_me),
+            )
+
+        check_me = 0
+
+    def test_first(foo):
+        global check_me
+
+        assert check_me == 1
+        assert foo == 42
+
+        check_me = 2
+
+    def test_second(foo):
+        global check_me
+
+        assert check_me == 1
+        assert foo == 42
+
+        check_me = 2
+    """
+    testdir.makepyfile(test_file)
+    rr = testdir.run(sys.executable, "-m", "pytest", "-v", *cmd_opts)
+    assert_outcomes(rr, {"passed": 2})
+
+
 def test_blockon_in_hook(testdir, cmd_opts, request):
     skip_if_reactor_not(request, "default")
     conftest_file = """