Tests: pathlib used where appropriate

Also fixed various pylint errors and style issues.

test/python/legacy_force/asgi.py

@@ -1,11 +1,10 @@
 def application(scope, receive=None, send=None):
     assert scope['type'] == 'http'
 
-    if receive == None and send == None:
+    if receive is None and send is None:
         return app_http
 
-    else:
-        return app_http(receive, send)
+    return app_http(receive, send)
 
 
 async def app_http(receive, send):
@@ -13,6 +12,8 @@ async def app_http(receive, send):
         {
             'type': 'http.response.start',
             'status': 200,
-            'headers': [(b'content-length', b'0'),],
+            'headers': [
+                (b'content-length', b'0'),
+            ],
         }
     )