Feature: improved `findAll` method

[mdjastrzebski]

Describe the Feature

We currently use ReactTestInstance.findAll method in order to traverse element tree. This is a basic tree walking algorithm that starts at the root and traverses recursively to the children.

There is one major issue with the current method: for query predicates that inspect all descendants (e.g. concat all string content) there is no easy way to find only the deepest element matching given predicate.

<Text testID="outer">
  <Text testID="inner">
    Hello.
  </Text>
</Text>

When using a predict that will concat all nested string contents, then both outer and inner text will be matched.

Possible Implementations

This should be a function, with similar signature:

function findAll(element: ReactTestInstance, predicate: (element: ReactTestInstance) => boolean, options: FindAllOptions)

• it should work by traversing tree top-down from root (as current algorithm)
• but it should be inspecting the elements on its way back, so that the deepest element is matched first
• having information about deeper element having been matched inside given branch it would prevent it's ancestor elements also getting match
• this should be an optional behavior controlled by option passed inside options argument. Proposed initial option name: deepestOnly (default false)
• it might be worth considering adding some additional argument to predicate callback to facilitate this

Applications

• This would be an internal API used by queries.
• It could allow us to improve some existing non-trivial queries, e.g. *ByText or *ByRole with name option

[rparthas]

I am interested to work on it.

[mdjastrzebski]

Go ahead @rparthas

[mdjastrzebski]

@rparthas I wanted to check if you still plan to contribute this feature?

[rparthas]

Yes I intend to. Got bit sidetracked