diff --git a/test/fixtures/server.py b/test/fixtures/server.py
index 07cd498..da1ba6e 100644
--- a/test/fixtures/server.py
+++ b/test/fixtures/server.py
@@ -74,7 +74,7 @@ def item_type(request):
     return request.param
 
 
-@pytest.fixture(params=[1, 3, 7])
+@pytest.fixture(params=[1, 3, 7, 100])
 def buffer_size(request):
     return request.param
 
@@ -94,7 +94,10 @@ def make_processor(operation, buffer_size=3):
         return response_payload
 
     def consume_buffer_now(buffer, data):
-        buffer_is_full = len(buffer) == buffer_size
+        current_buffer_size = len(buffer)
+        assert current_buffer_size <= buffer_size
+
+        buffer_is_full = current_buffer_size >= buffer_size
         last_request_has_been_sent = not data
         return buffer_is_full or last_request_has_been_sent