diff --git a/packages/google-api-core/tests/unit/gapic/test_requests.py b/packages/google-api-core/tests/unit/gapic/test_requests.py
index e046f31b828b..c3b87eef3e5a 100644
--- a/packages/google-api-core/tests/unit/gapic/test_requests.py
+++ b/packages/google-api-core/tests/unit/gapic/test_requests.py
@@ -27,9 +27,6 @@ def __init__(self, **kwargs):
         for k, v in kwargs.items():
             setattr(self, k, v)
 
-    def __contains__(self, key):
-        return hasattr(self, key)
-
 
 class MockProtoRequest:
     def __init__(self, **kwargs):
@@ -44,9 +41,6 @@ class MockValueErrorRequest:
     def HasField(self, key):
         raise ValueError("Mismatched field")
 
-    def __contains__(self, key):
-        return hasattr(self, key)
-
 
 # --- Parameterized Test ---