@Test
    void testEagerStreamedRenderingOnFreeze() {
        FreezingDataSource source = new FreezingDataSource();
        Chain<Processor> mainChain = new Chain<>("main", source);
        driver = new ProcessingTestDriver(mainChain);
        ProcessingTestDriver.MockResponseHandler responseHandler = driver.sendRequest("http://localhost/?chain=main");
        assertEquals(0, responseHandler.available(), "No data is available at this point");
        source.freeze.set(true);
        assertEquals("{\"datalist\":[{\"data\":\"d1\"}", responseHandler.read());
        source.addLastData.set(true); // signal completion
        assertEquals(",{\"data\":\"d2\"}]}", responseHandler.read());
        assertNull(responseHandler.read(), "Transmission completed");
    }
Tests that the ResponseStatus takes precedence over errors
container-core/src/test/java/com/yahoo/processing/handler/ProcessingHandlerTestCase.java