Test mode

docs/sanic/testing.rst

@@ -58,6 +58,36 @@ More information about
 the available arguments to `httpx` can be found
 [in the documentation for `httpx <https://www.encode.io/httpx/>`_.
 
+Additionally, Sanic has an asynchronous testing client. The difference is that the async client will not stand up an
+instance of your application, but will instead reach inside it using ASGI. All listeners and middleware are still
+executed.
+
+.. code-block:: python
+    @pytest.mark.asyncio
+    async def test_index_returns_200():
+        request, response = await app.asgi_client.put('/')
+        assert response.status == 200
+.. note::
+
+    Whenever one of the test clients run, you can test your app instance to determine if it is in testing mode:
+    `app.test_mode`.
+
+Additionally, Sanic has an asynchronous testing client. The difference is that the async client will not stand up an
+instance of your application, but will instead reach inside it using ASGI. All listeners and middleware are still
+executed.
+
+.. code-block:: python
+
+    @pytest.mark.asyncio
+    async def test_index_returns_200():
+        request, response = await app.asgi_client.put('/')
+        assert response.status == 200
+
+.. note::
+
+    Whenever one of the test clients run, you can test your app instance to determine if it is in testing mode:
+    `app.test_mode`.
+
 
 Using a random port
 -------------------

sanic/app.py

@@ -90,6 +90,7 @@ def __init__(
         self.named_response_middleware = {}
         # Register alternative method names
         self.go_fast = self.run
+        self.test_mode = False
 
     @property
     def loop(self):

sanic/testing.py

@@ -22,6 +22,14 @@ def __init__(self, app, port=PORT, host=HOST):
         self.port = port
         self.host = host
 
+        @app.listener("after_server_start")
+        def _start_test_mode(sanic, *args, **kwargs):
+            sanic.test_mode = True
+
+        @app.listener("before_server_end")
+        def _end_test_mode(sanic, *args, **kwargs):
+            sanic.test_mode = False
+
     def get_new_session(self):
         return httpx.AsyncClient(verify=False)
 
@@ -209,6 +217,14 @@ def __init__(
         def _collect_request(request):
             self.last_request = request
 
+        @app.listener("after_server_start")
+        def _start_test_mode(sanic, *args, **kwargs):
+            sanic.test_mode = True
+
+        @app.listener("before_server_end")
+        def _end_test_mode(sanic, *args, **kwargs):
+            sanic.test_mode = False
+
         app.request_middleware.appendleft(_collect_request)
 
     async def request(self, method, url, gather_request=True, *args, **kwargs):

tests/test_app.py

@@ -222,3 +222,28 @@ def handler(request):
 def test_app_name_required():
     with pytest.deprecated_call():
         Sanic()
+
+
+def test_app_has_test_mode_sync():
+    app = Sanic("test")
+
+    @app.get("/")
+    def handler(request):
+        assert request.app.test_mode
+        return text("test")
+
+    _, response = app.test_client.get("/")
+    assert response.status == 200
+
+
+# @pytest.mark.asyncio
+# async def test_app_has_test_mode_async():
+#     app = Sanic("test")
+
+#     @app.get("/")
+#     async def handler(request):
+#         assert request.app.test_mode
+#         return text("test")
+
+#     _, response = await app.asgi_client.get("/")
+#     assert response.status == 200