1 files changed, 12 insertions, 2 deletions
diff --git a/actionpack/test/dispatch/live_response_test.rb b/actionpack/test/dispatch/live_response_test.rb
index 336fdd569b..512f3a8a7a 100644
--- a/actionpack/test/dispatch/live_response_test.rb
+++ b/actionpack/test/dispatch/live_response_test.rb
@@ -35,6 +35,7 @@ module ActionController
           @response.stream.close
         }
 
+        @response.await_commit
         @response.each do |part|
           assert_equal 'foo', part
           latch.release
@@ -59,21 +60,30 @@ module ActionController
         assert_nil @response.headers['Content-Length']
       end
 
-      def test_headers_cannot_be_written_after_write
+      def test_headers_cannot_be_written_after_webserver_reads
         @response.stream.write 'omg'
+        latch = ActiveSupport::Concurrency::Latch.new
 
+        t = Thread.new {
+          @response.stream.each do |chunk|
+            latch.release
+          end
+        }
+
+        latch.await
         assert @response.headers.frozen?
         e = assert_raises(ActionDispatch::IllegalStateError) do
           @response.headers['Content-Length'] = "zomg"
         end
 
         assert_equal 'header already sent', e.message
+        @response.stream.close
+        t.join
       end
 
       def test_headers_cannot_be_written_after_close
         @response.stream.close
 
-        assert @response.headers.frozen?
         e = assert_raises(ActionDispatch::IllegalStateError) do
           @response.headers['Content-Length'] = "zomg"
         end