com.facebook.litho.testing.assertj

Class SubComponentDeepExtractor

java.lang.Object

com.facebook.litho.testing.assertj.SubComponentDeepExtractor

public final class SubComponentDeepExtractor
extends Object

An extractor to be used with org.assertj.core.api.Assertions#assertThat.

Recursively extracts sub components from a Component, wrapping them in an InspectableComponent.

Components are extracted in a depth-first way so that they match the hierarchy indices when going from top to bottom.

In most cases you will want to use the #deepSubComponentWith(ComponentContext, Condition) combinator.

Method Summary

Modifier and Type	Method and Description
static <any>	deepSubComponentWith(ComponentContext c, <any> inner) Verify that a component tree contains a component that matches the provided condition at any level in its tree.
List<InspectableComponent>	extract(Component input)
static SubComponentDeepExtractor	subComponentsDeeply(ComponentContext c) Extract sub components recursively, from a provided Component in a depth-first manner.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

extract

public List<InspectableComponent> extract(Component input)

subComponentsDeeply

public static SubComponentDeepExtractor subComponentsDeeply(ComponentContext c)

Extract sub components recursively, from a provided Component in a depth-first manner.

E.g.

  assertThat(lithoView).extracting(subComponentsDeeply(c)).hasSize(2);
 

deepSubComponentWith

public static <any> deepSubComponentWith(ComponentContext c,
                                         <any> inner)

Verify that a component tree contains a component that matches the provided condition at any level in its tree.

Note that asserting on indirect children breaks encapsulation and can lead to Change Detector Tests[0]. Prefer SubComponentExtractor#subComponentWith(ComponentContext, Condition) over this whenever possible.

Example Use

Suppose you have a MyWrapperComponentSpec that creates a Card which contains a Text for a text prop that your component accepts.

You want to ensure that the text truncation logic correctly applies to the text that sits inside the card. Using SubComponentExtractor#subComponentWith(ComponentContext, Condition) won't work here as it will only be able to make assertions on the Card but not the Text sitting inside.

 mComponent = MyWrapperComponent.create(c).text("I'm Mr. Meeseeks! Look at me!").build();
 assertThat(c, mComponent)
   .has(deepSubComponentWith(c, textEquals("I'm Mr. Meeseeks!")))
   .doesNotHave(deepSubComponentWith(c, text(containsString("wubba lubba dub dub"))));
 

For more applicable combinators, see below:

Parameters:

c - The ComponentContext used to create the tree.

inner - The condition that at least one sub component needs to match.

[0] https://testing.googleblog.com/2015/01/testing-on-toilet-change-detector-tests.html

See Also:

org.hamcrest.CoreMatchers, ComponentConditions