GuiceBrokenExample.java

import static org.junit.Assert.assertFalse;

import org.junit.Before;
import org.junit.Test;

import com.google.inject.AbstractModule;
import com.google.inject.Guice;
import com.google.inject.Injector;
import com.google.inject.matcher.Matchers;
import com.google.inject.spi.ProvisionListener;

public class GuiceBrokenExample
{
	private boolean failed = true;
	
	@Before
	public void resetFailure()
	{
		failed = true;
	}
	
	//When constructed in to the same injector, the test passes because the ListeningModule gets a
	// chance to notice the Injectable being provisioned
	@Test
	public void test()
	{
		Injector i = Guice.createInjector(new ListeningModule());
		i.getInstance(Injectable.class);
		assertFalse(failed);
	}
	
	//This test fails because the original injector actually constructs the Injectable instance
	// because it doesn't require anything from the listening module
	@Test
	public void testFails()
	{
		Injector i = Guice.createInjector();
		i = i.createChildInjector(new ListeningModule());
		i.getInstance(Injectable.class);
		assertFalse(failed);
	}
	
	private class ListeningModule extends AbstractModule
	{

		@Override
		protected void configure()
		{
			this.bindListener(Matchers.any(), new ProvListen());
		}
		
	}
	
	private class ProvListen implements ProvisionListener
	{

		@Override
		public <T> void onProvision(ProvisionInvocation<T> provision)
		{
			failed = false;
		}
	}
	
	public static class Injectable
	{
	}
}