diff --git a/docs/sanic/testing.rst b/docs/sanic/testing.rst
index 67506edc..0cf3ff40 100644
--- a/docs/sanic/testing.rst
+++ b/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
 -------------------
diff --git a/sanic/app.py b/sanic/app.py
index 5c805874..25139e1b 100644
--- a/sanic/app.py
+++ b/sanic/app.py
@@ -90,6 +90,7 @@ class Sanic:
         self.named_response_middleware = {}
         # Register alternative method names
         self.go_fast = self.run
+        self.test_mode = False
 
     @property
     def loop(self):
diff --git a/sanic/testing.py b/sanic/testing.py
index 36233e70..faabdfd1 100644
--- a/sanic/testing.py
+++ b/sanic/testing.py
@@ -22,6 +22,14 @@ class SanicTestClient:
         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 @@ class SanicASGITestClient(httpx.AsyncClient):
         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):
diff --git a/tests/test_app.py b/tests/test_app.py
index ab7da76d..c7791394 100644
--- a/tests/test_app.py
+++ b/tests/test_app.py
@@ -222,3 +222,28 @@ def test_handle_request_with_nested_sanic_exception(app, monkeypatch, caplog):
 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