Give a more descriptive error message if you try to call .success or …

….failure on a HttpUser request with missing catch_response=True

locust/clients.py

@@ -295,3 +295,20 @@ def failure(self, exc):
         if not isinstance(exc, Exception):
             exc = CatchResponseError(exc)
         self._manual_result = exc
+
+
+# Monkey patch Response class to give some guidance
+def _success(self):
+    raise LocustError(
+        "If you want to change the state of the request, you must pass catch_response=True. See http://docs.locust.io/en/stable/writing-a-locustfile.html#validating-responses"
+    )
+
+
+def _failure(self):
+    raise LocustError(
+        "If you want to change the state of the request, you must pass catch_response=True. See http://docs.locust.io/en/stable/writing-a-locustfile.html#validating-responses"
+    )
+
+
+Response.success = _success
+Response.failure = _failure

locust/contrib/fasthttp.py

@@ -370,12 +370,12 @@ def _content(self):
         return super()._content()
 
     def success(self):
-        raise Exception(
+        raise LocustError(
             "If you want to change the state of the request, you must pass catch_response=True. See http://docs.locust.io/en/stable/writing-a-locustfile.html#validating-responses"
         )
 
     def failure(self):
-        raise Exception(
+        raise LocustError(
             "If you want to change the state of the request, you must pass catch_response=True. See http://docs.locust.io/en/stable/writing-a-locustfile.html#validating-responses"
         )
 

locust/test/test_fasthttp.py

@@ -589,7 +589,7 @@ def on_failure(**kw):
     def test_missing_catch_response_true(self):
         # incorrect usage, missing catch_response=True
         with self.user.client.get("/fail") as resp:
-            self.assertRaises(Exception, resp.success)
+            self.assertRaises(LocustError, resp.success)
 
 
 class TestFastHttpSsl(LocustTestCase):

locust/test/test_http.py

@@ -273,6 +273,12 @@ def test_catch_response_missing_with_block(self):
         self.assertRaises(LocustError, r.success)
         self.assertRaises(LocustError, r.failure, "")
 
+    def test_missing_catch_response_true(self):
+        s = self.get_client()
+        # incorrect usage, missing catch_response=True
+        with s.get("/fail") as resp:
+            self.assertRaises(LocustError, resp.success)
+
     def test_user_context(self):
         class TestUser(HttpUser):
             host = f"http://127.0.0.1:{self.port}"