Testing a JAX-RS Web Service?

As James said; There is built-in test framework for Jersey. A simple hello world example can be like this:

pom.xml for maven integration. When you run mvn test. Frameworks start a grizzly container. You can use jetty or tomcat via changing dependencies.

...
<dependencies>
  <dependency>
    <groupId>org.glassfish.jersey.containers</groupId>
    <artifactId>jersey-container-servlet</artifactId>
    <version>2.16</version>
  </dependency>

  <dependency>
    <groupId>org.glassfish.jersey.test-framework</groupId>
    <artifactId>jersey-test-framework-core</artifactId>
    <version>2.16</version>
    <scope>test</scope>
  </dependency>

  <dependency>
    <groupId>org.glassfish.jersey.test-framework.providers</groupId>
    <artifactId>jersey-test-framework-provider-grizzly2</artifactId>
    <version>2.16</version>
    <scope>test</scope>
  </dependency>
</dependencies>
...

ExampleApp.java

import javax.ws.rs.ApplicationPath;
import javax.ws.rs.core.Application;

@ApplicationPath("/")
public class ExampleApp extends Application {

}

HelloWorld.java

import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("/")
public final class HelloWorld {

    @GET
    @Path("/hello")
    @Produces(MediaType.TEXT_PLAIN)
    public String sayHelloWorld() {

        return "Hello World!";
    }
}

HelloWorldTest.java

import org.glassfish.jersey.server.ResourceConfig;
import org.glassfish.jersey.test.JerseyTest;
import org.junit.Test;
import javax.ws.rs.core.Application;
import static org.junit.Assert.assertEquals;

public class HelloWorldTest extends JerseyTest {

    @Test
    public void testSayHello() {

        final String hello = target("hello").request().get(String.class);

        assertEquals("Hello World!", hello);
    }

    @Override
    protected Application configure() {

        return new ResourceConfig(HelloWorld.class);
    }
}

You can check this sample application.

You probably wrote some java code that implements your business logic and then you have generated the web services end point for it.

An important thing to do is to independently test your business logic. Since it's pure java code you can do that with regular JUnit tests.

Now, since the web services part is just an end point, what you want to make sure is that the generated plumbing (stubs, etc) are in sync with your java code. you can do that by writing JUnit tests that invoke the generated web service java clients. This will let you know when you change your java signatures without updating the web services stuff.

If your web services plumbing is automatically generated by your build system at every build, then it may not be necessary to test the end points (assuming it's all properly generated). Depends on your level of paranoia.

You can try out REST Assured which makes it very simple to test REST services and validating the response in Java (using JUnit or TestNG).

Jersey comes with a great RESTful client API that makes writing unit tests really easy. See the unit tests in the examples that ship with Jersey. We use this approach to test the REST support in Apache Camel, if you are interested the test cases are here