Avoid importing asyncio directly because that in turn initializes logging (#8)

Author: nicoddemus

_pytest/compat.py

@@ -19,11 +19,6 @@
     # Only available in Python 3.4+ or as a backport
     enum = None
 
-try:
-    import asyncio
-except ImportError:  # pragma: no cover
-    # Only available in Python 3.4+ or as a backport
-    asyncio = None
 
 _PY3 = sys.version_info > (3, 0)
 _PY2 = not _PY3
@@ -49,9 +44,17 @@ def _format_args(func):
 
 def is_generator(func):
     genfunc = inspect.isgeneratorfunction(func)
-    if asyncio is not None:
-        return genfunc and not asyncio.iscoroutinefunction(func)
-    return genfunc
+    return genfunc and not iscoroutinefunction(func)
+
+
+def iscoroutinefunction(func):
+    """Return True if func is a decorated coroutine function.
+
+    Note: copied and modified from Python 3.5's builtin couroutines.py to avoid import asyncio directly,
+    which in turns also initializes the "logging" module as side-effect (see issue #8).
+    """
+    return (getattr(func, '_is_coroutine', False) or
+           (hasattr(inspect, 'iscoroutinefunction') and inspect.iscoroutinefunction(func)))
 
 
 def getlocation(function, curdir):

testing/test_compat.py

@@ -15,8 +15,8 @@ def foo():
     assert not is_generator(foo)
 
 
+@pytest.mark.skipif(sys.version_info < (3, 4), reason='asyncio available in Python 3.4+')
 def test_is_generator_asyncio(testdir):
-    pytest.importorskip('asyncio')
     testdir.makepyfile("""
         from _pytest.compat import is_generator
         import asyncio
@@ -27,7 +27,8 @@ def baz():
         def test_is_generator_asyncio():
             assert not is_generator(baz)
     """)
-    result = testdir.runpytest()
+    # avoid importing asyncio into pytest's own process, which in turn imports logging (#8)
+    result = testdir.runpytest_subprocess()
     result.stdout.fnmatch_lines(['*1 passed*'])