Acceptance testing preloading of data into GAE dev server datastore

Question

In my application I have a set of of DAOs which I inject into my application layer. For an acceptance test I'm writing, I want to preload the dev_server datastore with data, so I use the same Spring config in my JUnit test (using the @ContextConfiguration annotation) to inject an instance of the relevant DAO into my test. When I actually go to store some data eg:

dao.add(entity)

I get the dreaded "No API environment is registered for this thread."

Caused by: java.lang.NullPointerException: No API environment is registered for this thread.
 at com.google.appengine.api.datastore.DatastoreApiHelper.getCurrentAppId(DatastoreApiHelper.java:108)
 at com.google.appengine.api.datastore.DatastoreApiHelper.getCurrentAppIdNamespace(DatastoreApiHelper.java:118)
    ....

This is probably because my test case hasn't read in the GAE application-web.xml with the app details (although I'm guessing here I could really be wrong); so it doesn't know to write to the same datastore that the app running on the dev_server is reading/writing to.

How can I get my test to "point" to the same datastore as the app? Is there some "datasource" mechanism that I can inject both into the app and the test? Is there a way to get my test to force the datastore api to read the needed config?

Answer 1

Here is a page that talks about how to do unit tests that connect to a dev datastore. Is this the kind of thing you're looking for? Basically it talks about two classes, LocalServiceTestHelper and LocalDatastoreServiceTestConfig that you can use to set up an environment for testing. While the example given is for unit tests, I believe it will also work for your situation.

You can then configure things like whether the dev datastore is written to disk or just kept in memory (for faster tests). If you want this data to go to the same place as your dev server, you will probably want to adjust this, as I think the default is the "in memory" option. If you look at the javadoc there is a "setBackingStoreLocation" method where you can point to whatever file you want.

Answer 2

I've found the solution!!!!

For some reason the Namespace, AppID and the AuthDomain fields of the test datastore have to match that of the dev_server, then the dev_server can see the entities inserted by the test.

You can see the values for the environment (dev_server or test code) with the following statements

System.out.println(NamespaceManager.get());
System.out.println(ApiProxy.getCurrentEnvironment().getAppId());
System.out.println(ApiProxy.getCurrentEnvironment().getAuthDomain());

In your instance of LocalServiceTestHelper (eg: gaeHelper), you can set the values for the test environment

// the NamespaceManager is thread local.
NamespaceManager.set(NamespaceManager.getGoogleAppsNamespace());
gaeHelper.setEnvAppId(<the name of your app in appengine-web.xml>);
gaeHelper.setEnvAuthDomain("gmail.com");

Then the dev_server will see your entities. However because of synchronisation issues, if the test writes to the datastore after the dev_server has been started the dev_server wont see it unless it can be forced to reread the file (which I haven't figured out yet). Else the server has to be restarted.

Answer 3

I've found a workaround, although it's not very nice because each test method doesn't clean up the Datastore, as explained in the article Local Unit Testing for Java, however, the Datastore starts clean each time the Test class is run, so it's not so bad, provided that you're careful about that.

The problem is, that when using SpringJUnit4ClassRunner, the spring environment is created before the @Before annotation can be run, the solution is use @BeforeClass and use a static variable for LocalServiceTestHelper, to have them created before the Spring Environment is set up.

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:META-INF/spring/context-test.xml")
@Transactional
public class MyTest {


    @Inject
    private MyService myService;

    private static final LocalServiceTestHelper helper = 
        new LocalServiceTestHelper(new LocalDatastoreServiceTestConfig());

    @BeforeClass
    public static void beforeClass() {
        helper.setUp();
    }

    @AfterClass
    public static void afterClass() {
        helper.tearDown();
    }

If anyone has a better solution, I'll be glad to hear!