Add PHP 8.0 named parameters support

[BrianHenryIE]

Summary

Add support for using PHP 8.0 named parameters.

Closes:

No issue opened.

Details

Trying to call a mocked function like:

$value = get_transient(
    transient: 'my-transient-name'
);

results in:

Error : Unknown named parameter $transient

This now works:

WP_Mock::userFunction('get_transient', [
    'times'  => 1,
    'args'   => [
        'transient' => 'my-transient-name',
    ],
    'return' => 'the-mocked-transient-value',
]);

The changes use the args array's keys as the parameter names in the mocked function.

NB: this does not work:

WP_Mock::userFunction('get_transient')->once()->with(['transient' => 'my-transient-name'])->andReturn('the-mocked-transient-value');

The Functions::createFunction() has already been called and the function skeleton built and eval()'d, which is where the parameter names must be added.

Contributor checklist

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly
• I have added tests to cover changes introduced by this pull request
• All new and existing tests pass

Testing

One test added which skips if the PHP version is too low.

Reviewer checklist

• Code changes review
• Documentation changes review
• Unit tests pass
• Static analysis passes

[coveralls]

coverage: 66.451% (+0.3%) from 66.142%
when pulling 8fe92eb on BrianHenryIE:named-parameters
into 446ea70 on 10up:trunk.