fix: reset regexg to prevent regexg with global flags to not match every element

[timdeschryver]

What: Resolves #1115

Why:

The instance of a regex that's using the global flag hold a lastIndex state. This might give false positive results.

For example:

const g = /foo/g
g.test('foo') // |> true
g.test('foo') // |> false because lastIndex is 3
g.test('foo') // |> true because lastIndex is 0 again
g.test('foo') // |> false because lastIndex is 3

How:

Added a reproduction test case. Recreate a new regex instance from the original regex.

An alternative would be to reset the lastIndex to 0 after the check.

Checklist:

• [ ] Documentation added to the docs site
• [x] Tests
• [ ] TypeScript definitions updated
• [x] Ready to be merged

[codesandbox-ci[bot]]

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Sandbox	Source
react-testing-library-examples	Configuration
react-testing-library demo	Issue #1115

[codecov[bot]]

Codecov Report

Merging #1116 (714007e) into main (90fba31) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main     #1116   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           25        25           
  Lines          955       961    +6     
  Branches       311       312    +1     
=========================================
+ Hits           955       961    +6     

Flag	Coverage Δ
node-12	?
node-14	?
node-16	100.00% <100.00%> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/matches.ts	100.00% <100.00%> (ø)

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[eps1lon]

@timdeschryver I think you need to push an empty commit or rebase and drop the merge commit. Codecov may not like merge commits which is a result of updating the branch from the GitHub UI.

[timdeschryver]

@eps1lon Done. No problem, it was a team effort so we have me to blame aswell This change had a bit more catches than forseen 😅

[github-actions[bot]]

:tada: This PR is included in version 8.11.4 :tada:

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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