Integration tests for Google App Engine (java)

Question

I\'m trying to develop some effective integration tests for my GAE/j application. I\'m familiar with https://developers.google.com/appengine/docs/java/tools/localunittesting --

Answer 1

Basically, you need to do two things:

1. Add two servlets (or whatever), which must be only enabled during testing, which allow you to invoke setup and teardown on the helper remotely.
2. Make your servlet engine serve requests in a completely single-threaded way. This is needed because for some reason, the Helper class Google provides only takes effect in the current thread.

Answer 2

I agree this issue is poorly documented.
I managed to write an end-to-end test that starts a server as a black box and sends it HTTP requests.

It works like this:

package com.project.org;

import static org.junit.Assert.assertEquals;
import java.io.File;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import com.google.appengine.api.urlfetch.HTTPResponse;
import com.google.appengine.api.urlfetch.URLFetchServiceFactory;
import com.google.appengine.tools.development.testing.BaseDevAppServerTestConfig;
import com.google.appengine.tools.development.testing.DevAppServerTest;
import com.google.appengine.tools.development.testing.DevAppServerTestRunner;
import com.google.appengine.tools.development.testing.LocalServiceTestHelper;

@RunWith(DevAppServerTestRunner.class)
@DevAppServerTest(HelloWorldTest.TestConfig.class)
public class HelloWorldTest {

  public class TestConfig extends BaseDevAppServerTestConfig {

    @Override public File getSdkRoot() {
      // You may need to tweak this.
      return new File("../../appengine-java-sdk-1.9.15");
    }

    @Override public File getAppDir() {
      return new File("war");
    }

    @Override
    public List<URL> getClasspath() {
      // There may be an easier way to do this.
      List<URL> classPath = new ArrayList<>();
      try {
        String separator = System.getProperty("path.separator");
        String[] pathElements = System.getProperty("java.class.path").split(separator);
        for (String pathElement : pathElements) {
          classPath.add(new File(pathElement).toURI().toURL());
        }
      }
      catch (MalformedURLException e) {
        throw new RuntimeException(e);
      }
      return classPath;
    }
  }

  private final LocalServiceTestHelper testHelper;
  private final String port;

  public HelloWorldTest() {
    testHelper = new LocalServiceTestHelper();
    port = System.getProperty("appengine.devappserver.test.port");
  }

  @Before public void setUpServer() {
    testHelper.setUp();
  }

  @After public void tearDown() {
    testHelper.tearDown();
  }

  @Test public void testHelloWorld() throws Exception {
    URL url = new URL("http://localhost:" + port + "/hello");
    HTTPResponse response = URLFetchServiceFactory.getURLFetchService().fetch(url);
    assertEquals(200, response.getResponseCode());
    assertEquals("Hello world!", new String(response.getContent(), "UTF-8"));
  }
}

---

Now the issue I have is that if you have two of those tests, with each passing individually, you cannot run them in the same binary. The exception on line 37 of this file get thrown:

IllegalStateException("Dev Appserver is already running.")

Not sure how to fix this.