Move tests for async openapi func to dedicated test file

tests/test_application.py

@@ -1,6 +1,5 @@
 import pytest
 from dirty_equals import IsDict
-from fastapi import FastAPI
 from fastapi.testclient import TestClient
 
 from .main import app
@@ -53,18 +52,6 @@ def test_enum_status_code_response():
     assert response.json() == "foo bar"
 
 
-def test_allow_async_openapi():
-    async def async_openapi():
-        return {"foo": "bar"}
-
-    mod_app = FastAPI()  # use fresh instance to not affect other tests
-    mod_app.openapi = async_openapi
-    mod_client = TestClient(mod_app)
-    response = mod_client.get("/openapi.json")
-    assert response.status_code == 200, response.text
-    assert response.json() == {"foo": "bar"}
-
-
 def test_openapi_schema():
     response = client.get("/openapi.json")
     assert response.status_code == 200, response.text

tests/test_openapi_async.py

@@ -0,0 +1,14 @@
+from fastapi import FastAPI
+from fastapi.testclient import TestClient
+
+
+def test_allow_async_openapi():
+    async def async_openapi():
+        return {"foo": "bar"}
+
+    mod_app = FastAPI()  # use fresh instance to not affect other tests
+    mod_app.openapi = async_openapi
+    mod_client = TestClient(mod_app)
+    response = mod_client.get("/openapi.json")
+    assert response.status_code == 200, response.text
+    assert response.json() == {"foo": "bar"}