feat: toHaveTextContent() matcher

[mdjastrzebski]

Summary

Implement toHaveTextContent() Jest matcher, with altered API - pls review below section and state your opinion about this change.

API change proposal (decision to make)

Jest DOM & legacy Jest Native matchers had following characteristics:

1. Both did perform partial match by default. The only way to perform exact match was to pay Regex including ^/$ start of string/end of string characters.
2. (Jest DOM only) The only option was normalizeWhitespace: boolean = true' which performed default normalization (collapse whitespace). Jest Native did not allow options.

This PR proposes following changes

1. Perform exact match by default. Partial match can be achieved using { exact: false } option or by using basic regex.
2. Support the same TextMatchOptions (exact + normalizer) as most of our queries.

Both of these changes would bring this matcher inline with getByText query, which uses exact match as default, and allows TextMatchOptions. I would argue that internal RNTL consistency is a more important to our users than replicating internal inconsistencies of RTL/Jest DOM matcher.

This PR change partially contradicts with our long-standing goal for making API maximally compatible with RTL's API. We already did that in case of making all queries respect a11y hidden attributes (where in RTL only *ByRole does it). I would suggest reinterpreting it in a somewhat more flexible way, where we would make API the same if it's good, but if it has some problems, we would fix it, while also allowing user to achieve RTL behavior using some option(s).

Test plan

Added relevant unit tests.

[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.01% 🎉

Comparison is base (344e9b3) 97.69% compared to head (9343602) 97.71%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1461      +/-   ##
==========================================
+ Coverage   97.69%   97.71%   +0.01%     
==========================================
  Files          78       79       +1     
  Lines        4603     4640      +37     
  Branches      670      675       +5     
==========================================
+ Hits         4497     4534      +37     
  Misses        106      106              

Files Changed	Coverage Δ
src/helpers/text-content.ts	100.00% <ø> (ø)
src/helpers/matchers/matchTextContent.ts	100.00% <100.00%> (ø)
src/matchers/extend-expect.ts	100.00% <100.00%> (ø)
src/matchers/to-have-text-content.tsx	100.00% <100.00%> (ø)

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[pierrezimmermannbam]

Looks good to me! I just have a question, I understood that we would start by exposing jest native matchers prefixed with legacy to ease migration, is it still the plan? If so shouldn't we start with that?

[mdjastrzebski]

@pierrezimmermannbam re legacy matchers. Yes that is still the plan. I plan to do it in the @testing-library/jest-native matchers as optional import: import '@testining-library/jest-native/legacy-extend-expect instead of typical import '@testining-library/jest-native/extend-expect.

That way it would be still available for a very long time but we would not have to manage it in RNTL repo.

[mdjastrzebski]

🎉 Release in version: v12.4.0