public void testEnvironmentOperations() {
DispatcherServlet servlet = new DispatcherServlet();
ConfigurableEnvironment defaultEnv = servlet.getEnvironment();
assertThat(defaultEnv, notNullValue());
ConfigurableEnvironment env1 = new StandardServletEnvironment();
servlet.setEnvironment(env1); // should succeed
assertThat(servlet.getEnvironment(), sameInstance(env1));
try {
servlet.setEnvironment(new DummyEnvironment());
fail("expected IllegalArgumentException for non-configurable Environment");