Fix normalize_path_middleware behavior for patch without slash (3669)

CHANGES/3669.bugfix

@@ -0,0 +1 @@
+Fix ``web_middlewares.normalize_path_middleware`` behavior for patch without slash.

aiohttp/web_middlewares.py

@@ -96,7 +96,7 @@ async def impl(request: Request, handler: _Handler) -> StreamResponse:
             if merge_slashes and append_slash:
                 paths_to_check.append(
                     re.sub('//+', '/', path + '/'))
-            if merge_slashes and remove_slash:
+            if merge_slashes and remove_slash and path.endswith('/'):
                 merged_slashes = re.sub('//+', '/', path)
                 paths_to_check.append(merged_slashes[:-1])
 

tests/test_web_middleware.py

@@ -151,7 +151,9 @@ async def test_remove_trailing_when_necessary(self, path,
         ('/resource2?p1=1&p2=2', 404),
         ('/resource2/?p1=1&p2=2', 200),
         ('/resource2/a/b%2Fc', 404),
-        ('/resource2/a/b%2Fc/', 200)
+        ('/resource2/a/b%2Fc/', 200),
+        ('/resource12', 404),
+        ('/resource123456', 404),
     ])
     async def test_no_trailing_slash_when_disabled(
             self, path, status, cli):
@@ -271,10 +273,6 @@ async def test_remove_and_merge_slash(self, path, status, cli) -> None:
         assert resp.status == status
         assert resp.url.query == URL(path).query
 
-    async def test_cannot_remove_and_add_slash(self) -> None:
-        with pytest.raises(AssertionError):
-            web.normalize_path_middleware(append_slash=True, remove_slash=True)
-
 
 async def test_old_style_middleware(loop, aiohttp_client) -> None:
     async def handler(request):
@@ -425,6 +423,7 @@ async def handler(request):
         return web.Response(body=b'OK')
 
     class Middleware:
+
         @web.middleware
         async def call(self, request, handler):
             resp = await handler(request)