In this example, JUnit is used to cover all three tiers of testing - unit tests, integration tests, and UI/acceptance tests. Unit tests are written in SauceStatusPageDecoratorTest.java, which test the messages returned by the PageDecorator, depending on the Sauce Cloud's status. Integration tests are written in IntegrationIT.java, which use Selenium 3 to automate a real browser and simulate user actions to ensure that the plugin is properly installed on Jenkins. UI/acceptance tests are also included, which verify that the plugin displays the correct message when the Sauce Labs service is up or down. The code example demonstrates how simple it is to cover all three tiers of testing in one JUnit test suite.