concept Jetty in category java

This is an excerpt from Manning's book JUnit in Action, Second Edition. Login to get full access to this book.

Fortunately, an easier solution exists using an embedded web server. Because we’re testing in Java, the easiest solution is to use a Java web server that you can embed in the test case. You can use the free and open source Jetty server for this exact purpose. In this book, we use Jetty to set up our stubs. For more information about Jetty, visit http://www.eclipse.org/jetty/.

We use Jetty because it’s fast (important when running tests), it’s lightweight, and your test cases can programmatically control it. In addition, Jetty is a very good web, servlet, and JSP container that you can use in production. You seldom need this for most tests, but it’s always nice to use best-of-breed technology.

Using Jetty allows you to eliminate the drawbacks outlined previously: the JUnit test case starts the server, you write the tests in Java in one location, and automating the test suite is a nonissue. Thanks to Jetty’s modularity, the real point of the exercise is to stub only the Jetty handlers and not the whole server from the ground up.

Listing 6.3. First test to verify that WebClient works with a valid URL

[...] import java.net.URL; import org.junit.test; import org.junit.Before; import org.junit.After; public class TestWebClientSkeleton { @Before public void setUp() { } @After public void tearDown() { // Stop Jetty. } @Test public void testGetContentOk() throws Exception { WebClient client = new WebClient(); String result = client.getContent(new URL( "http://localhost:8080/testGetContentOk")); assertEquals ("It works", result); } }

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In order to implement the @Before and @After methods, you have two options. You can prepare a static page containing the text "It works", which you put in the document root (controlled by the call to context.setResourceBase(String) in listing 6.2). Alternatively, you can configure Jetty to use your own custom Handler that returns the string "It works" instead of getting it from a file. This is a much more powerful technique, because it lets you unit test the case when the remote HTTP server returns an error code to your WebClient client application.

6.2.2. Using Jetty as an embedded server

In order to understand how to set up and control Jetty from your tests, let’s implement a simple example. Listing 6.2 shows how to start Jetty from Java and how to define a document root (/) from which to start serving files.

Listing 6.2. Starting Jetty in embedded mode—JettySample class