PolyBindTest

PolyBindTest.java

  @Test
  public void foo()
  {
    // The test adds following things :
    // 1. Adds three property KVs (prop1, goA), (prop2, goB), (prop3, goA)
    // 2. Adds two options for Gogo.class in separate modules : GoA and GoB which have binding keys as 'goA' and 'goB'
    // 3. Adds three choices for Gogo.class in separate modules which correspond to the three properties
    // 4. checks via injector that first and third choice create GoA instances whereas choice second creates GoB instance
    props = new Properties();
    props.setProperty("prop1", "goA");
    props.setProperty("prop2", "goB");
    props.setProperty("prop3", "goA");
    injector = Guice.createInjector(
        Iterables.concat(
            Collections.singletonList(
                (Module) binder -> {
                  binder.bind(Properties.class).toInstance(props); // bind properties
                }
            ),
            Collections.singletonList(
                (Module) binder -> {
                  PolyBind.optionBinder(binder, Key.get(Gogo.class))
                          .addBinding("goA")
                          .to(GoA.class); // bind one option
                }
            ),
            Collections.singletonList(
                (Module) binder -> {
                  PolyBind.optionBinder(binder, Key.get(Gogo.class))
                          .addBinding("goB")
                          .to(GoB.class); // bind another option
                }
            ),
            Collections.singletonList(
                (Module) binder -> {
                  PolyBind.createChoiceWithName(
                      binder,
                      "prop1",
                      Key.get(Gogo.class),
                      null,
                      Key.get(Gogo.class, Names.named("goA1"))
                  ).in(Singleton.class); // create a choice with prop1 and name goA1
                }
            ),
            Collections.singletonList(
                (Module) binder -> {
                  PolyBind.createChoiceWithName(
                      binder,
                      "prop2",
                      Key.get(Gogo.class),
                      null,
                      Key.get(Gogo.class, Names.named("goB"))
                  ).in(Singleton.class); // create a choice with prop2 and name goB
                }
            ),
            Collections.singletonList(
                (Module) binder -> {
                  PolyBind.createChoiceWithName(
                      binder,
                      "prop3",
                      Key.get(Gogo.class),
                      null,
                      Key.get(Gogo.class, Names.named("goA2"))
                  ).in(Singleton.class); // create a choice with prop3 and name goA2
                }
            )
        )
    );

    Gogo goA1 = injector.getInstance(Key.get(Gogo.class, Names.named("goA1")));
    Gogo goB = injector.getInstance(Key.get(Gogo.class, Names.named("goB")));
    Gogo goA2 = injector.getInstance(Key.get(Gogo.class, Names.named("goA2")));
    Assert.assertTrue(goA1 instanceof GoA);
    Assert.assertTrue(goB instanceof GoB);
    Assert.assertTrue(goA2 instanceof GoA);
  }

// method to support Named Interface Key for creation of multiple object of same type but with different names
// Added in PolyBind.java class
 public static <T> ScopedBindingBuilder createChoiceWithName(
     Binder binder,
     String property,
     Key<T> interfaceKey,
     @Nullable Key<? extends T> defaultKey,
     @Nullable Key<T> namedInterfaceKey
 )
 {
    ConfiggedProvider<T> provider = new ConfiggedProvider<>(interfaceKey, property, defaultKey, null);
    if (namedInterfaceKey == null) {
      return binder.bind(interfaceKey).toProvider(provider);
    }
    return binder.bind(namedInterfaceKey).toProvider(provider);
 }