@Test
    public void testHELLO() {
        try {
            SparkTestUtil.UrlResponse response = http.get(HELLO);
            assertEquals(200, response.status);
            assertEquals(HELLO_WORLD, response.body);
        } catch (Throwable e) {
            throw new RuntimeException(e);
        }
    }
Validates and shows the "rules" for how response "body" is set.
src/test/java/spark/ResponseBodyTest.java