core/test/com/google/inject/BindingOrderTest.java

/**
 * Copyright (C) 2006 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.inject;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicReference;
import junit.framework.TestCase;

/**
 * @author jessewilson@google.com (Jesse Wilson)
 */
public class BindingOrderTest extends TestCase {

  public void testBindingOutOfOrder() {
    Guice.createInjector(new AbstractModule() {
      protected void configure() {
        bind(BoundFirst.class);
        bind(BoundSecond.class).to(BoundSecondImpl.class);
      }
    });
  }

  public static class BoundFirst {
    @Inject public BoundFirst(BoundSecond boundSecond) { }
  }

  interface BoundSecond { }
  static class BoundSecondImpl implements BoundSecond { }

  public void testBindingOrderAndScopes() {
    Injector injector = Guice.createInjector(new AbstractModule() {
      protected void configure() {
        bind(A.class);
        bind(B.class).asEagerSingleton();
      }
    });

    assertSame(injector.getInstance(A.class).b, injector.getInstance(A.class).b);
  }

  public void testBindingWithExtraThreads() throws InterruptedException {
    final CountDownLatch ready = new CountDownLatch(1);
    final CountDownLatch done = new CountDownLatch(1);
    final AtomicReference<B> ref = new AtomicReference<B>();

    final Object createsAThread = new Object() {
      @Inject void createAnotherThread(final Injector injector) {
        new Thread() {
          public void run() {
            ready.countDown();
            A a = injector.getInstance(A.class);
            ref.set(a.b);
            done.countDown();
          }
        }.start();

        // to encourage collisions, we make sure the other thread is running before returning
        try {
          ready.await();
        } catch (InterruptedException e) {
          throw new RuntimeException(e);
        }
      }
    };
    
    Guice.createInjector(new AbstractModule() {
      protected void configure() {
        requestInjection(createsAThread);
        bind(A.class).toInstance(new A());
      }
    });

    done.await();
    assertNotNull(ref.get());
  }

  static class A {
    @Inject B b;
  }

  static class B { }
}