How to use

InnerUpdate

in

com.spotify.mobius.extras.patterns

@Nonnull
public final Next<M, F> update(M model, E event) {
 MI innerModel = checkNotNull(modelExtractor().apply(model));
 EI innerEvent = checkNotNull(eventExtractor().apply(event));
 Next<MI, FI> innerNext = checkNotNull(innerUpdate().update(innerModel, innerEvent));
 M newModel = model;
 boolean modelUpdated = innerNext.hasModel();
 if (modelUpdated) {
  newModel = checkNotNull(modelUpdater().apply(model, innerNext.modelUnsafe()));
 }
 return checkNotNull(
   innerEffectHandler().handleInnerEffects(newModel, modelUpdated, innerNext.effects()));
}

@Test
public void innerUpdateCannotReturnNull() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> null)
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler(ignoreEffects())
     .build();
 try {
  innerUpdate.update("model", "event");
  fail("did not throw null pointer exception");
 } catch (NullPointerException e) {
  // Success.
 }
}

@Test
public void canExtractInnerEvent() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> "extracted_event")
     .innerUpdate((model, event) -> Next.next(event))
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler(ignoreEffects())
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasModel("extracted_event"));
}

@Test
public void callsInnerUpdate() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> Next.next("inner_update"))
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler(ignoreEffects())
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasModel("inner_update"));
}

@Test
public void updatedModelCallsModelUpdater() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> Next.next("inner_update"))
     .modelUpdater((m, mi) -> "model_updater")
     .innerEffectHandler(ignoreEffects())
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasModel("model_updater"));
}

@Test
public void canExtractInnerModel() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> "extracted_model")
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> Next.next(model))
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler(ignoreEffects())
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasModel("extracted_model"));
}

@Test
public void noChangeDoesNotCallModelUpdater() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> noChange())
     .modelUpdater((m, mi) -> "model_updater")
     .innerEffectHandler(ignoreEffects())
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasNothing());
}

@Test
public void cannotExtractNullEvent() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> null)
     .innerUpdate((model, event) -> Next.next(model))
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler(ignoreEffects())
     .build();
 try {
  innerUpdate.update("model", "event");
  fail("did not throw null pointer exception");
 } catch (NullPointerException e) {
  // Success.
 }
}

@Test
public void cannotExtractNullModel() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> null)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> Next.next(model))
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler(ignoreEffects())
     .build();
 try {
  innerUpdate.update("model", "event");
  fail("did not throw null pointer exception");
 } catch (NullPointerException e) {
  // Success.
 }
}

@Test
public void dispatchEffectCallsInnerEffectHandler() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> dispatch(effects("1", "2", "3")))
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler((model, updated, effects) -> Next.next("effect_handler"))
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasModel("effect_handler"));
}

@Test
public void noEffectsStillCallsInnerEffectHandler() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> Next.next("inner_update"))
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler((model, updated, effects) -> Next.next("effect_handler"))
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasModel("effect_handler"));
 assertThat(next, NextMatchers.<String, String>hasNoEffects());
}

@Test
public void noChangeNoEffectsStillCallsInnerEffectHandler() throws Exception {
 InnerUpdate<String, String, String, String, String, String> innerUpdate =
   InnerUpdate.<String, String, String, String, String, String>builder()
     .modelExtractor(m -> m)
     .eventExtractor(e -> e)
     .innerUpdate((model, event) -> noChange())
     .modelUpdater((m, mi) -> mi)
     .innerEffectHandler((model, updated, effects) -> Next.next("effect_handler"))
     .build();
 Next<String, String> next = innerUpdate.update("model", "event");
 assertThat(next, NextMatchers.<String, String>hasModel("effect_handler"));
 assertThat(next, NextMatchers.<String, String>hasNoEffects());
}

 @Test
 public void updatedModelNoEffectsStillCallsInnerEffectHandler() throws Exception {
  InnerUpdate<String, String, String, String, String, String> innerUpdate =
    InnerUpdate.<String, String, String, String, String, String>builder()
      .modelExtractor(m -> m)
      .eventExtractor(e -> e)
      .innerUpdate((model, event) -> Next.next("inner_update"))
      .modelUpdater((m, mi) -> mi)
      .innerEffectHandler((model, updated, effects) -> Next.next("effect_handler"))
      .build();

  Next<String, String> next = innerUpdate.update("model", "event");

  assertThat(next, NextMatchers.<String, String>hasModel("effect_handler"));
  assertThat(next, NextMatchers.<String, String>hasNoEffects());
 }
}