BaseServerTest.java

package shouty.web;

import com.mockrunner.mock.web.MockFilterConfig;
import com.mockrunner.mock.web.MockHttpServletRequest;
import com.mockrunner.mock.web.WebMockObjectFactory;
import com.mockrunner.servlet.ServletTestModule;
import org.junit.Before;
import spark.servlet.SparkApplication;
import spark.servlet.SparkFilter;

import javax.servlet.Filter;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletResponse;

/**
 * This class hooks up our Spark app with Mockrunner -
 * a library for unit testing servlets (as well as other
 * J2EE APIs).
 * <p>
 * If you're using a different web framework than Spark,
 * you should still be able to use Mockrunner - you just
 * have to wire it up slightly differently.
 */
public abstract class BaseServerTest {
    private ServletTestModule tester;
    private WebMockObjectFactory factory;

    @Before
    public void createStubContainer() throws ServletException {
        factory = new WebMockObjectFactory();
        tester = new ServletTestModule(factory);

        MockFilterConfig filterConfig = new MockFilterConfig();
        Filter sparkFilter = new SparkFilter() {
            @Override
            protected SparkApplication getApplication(FilterConfig filterConfig) throws ServletException {
                return createServer();
            }
        };

        sparkFilter.init(filterConfig);
        tester.addFilter(sparkFilter);
        tester.setDoChain(true);
        factory.getMockRequest().setContextPath("");
    }

    protected abstract SparkApplication createServer();

    protected void get(String requestUri) {
        MockHttpServletRequest req = factory.getMockRequest();
        req.setRequestURI(requestUri);
        tester.doGet();
    }

    protected String getResponseBody() {
        return tester.getOutput();
    }

    protected HttpServletResponse getResponse() {
        return (HttpServletResponse) tester.getFilteredResponse();
    }
}

ServerTest.java

package shouty.web;

import org.junit.Test;
import shouty.core.Person;
import spark.servlet.SparkApplication;

import javax.servlet.ServletException;
import java.util.HashMap;
import java.util.Map;

import static org.junit.Assert.assertEquals;

public class ServerTest extends BaseServerTest {
    private final Map<String, Person> people = new HashMap<>();

    @Override
    protected SparkApplication createServer() {
        return new Server(people);
    }

    @Test
    public void shouldRespondWithHello() throws ServletException {
        get("/");
        assertEquals("Hello World", getResponseBody());
        assertEquals(200, getResponse().getStatus());
    }
}