Move compat tests to a single file using testdir

This avoids having to resort to skipping modules in conftest.py file and avoids flake8 errors

testing/conftest.py

@@ -1,7 +0,0 @@
-import sys
-
-collect_ignore = []
-if sys.version_info[0] < 3:
-    collect_ignore.append("test_compat_3.py")
-if sys.version_info < (3, 5):
-    collect_ignore.append("test_compat_35.py")

testing/test_compat.py

@@ -1,3 +1,6 @@
+import sys
+
+import pytest
 from _pytest.compat import is_generator
 
 
@@ -10,3 +13,37 @@ def test_is_generator():
 
     assert is_generator(zap)
     assert not is_generator(foo)
+
+
+def test_is_generator_asyncio(testdir):
+    pytest.importorskip('asyncio')
+    testdir.makepyfile("""
+        from _pytest.compat import is_generator
+        import asyncio
+        @asyncio.coroutine
+        def baz():
+            yield from [1,2,3]
+
+        def test_is_generator_asyncio():
+            assert not is_generator(baz)
+    """)
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines(['*1 passed*'])
+
+
+@pytest.mark.skipif(sys.version_info < (3, 5), reason='async syntax available in Python 3.5+')
+def test_is_generator_async_syntax(testdir):
+    testdir.makepyfile("""
+        from _pytest.compat import is_generator
+        def test_is_generator_py35():
+            async def foo():
+                await foo()
+
+            async def bar():
+                pass
+
+            assert not is_generator(foo)
+            assert not is_generator(bar)
+    """)
+    result = testdir.runpytest()
+    result.stdout.fnmatch_lines(['*1 passed*'])

testing/test_compat_3.py

@@ -1,15 +0,0 @@
-import pytest
-from _pytest.compat import is_generator
-try:
-    import asyncio
-except ImportError:
-    asyncio = None
-
-
-@pytest.mark.skipif(asyncio is None, reason='asyncio is not installed')
-def test_is_generator():
-    @asyncio.coroutine
-    def baz():
-        yield from [1,2,3]
-
-    assert not is_generator(baz)

testing/test_compat_35.py

@@ -1,12 +0,0 @@
-from _pytest.compat import is_generator
-
-
-def test_is_generator_py35():
-    async def foo():
-        await foo()
-
-    async def bar():
-        pass
-
-    assert not is_generator(foo)
-    assert not is_generator(bar)