Allow providing named arguments from a data provider

[jnoordsij]

Using a data provider you can easily run the same test for a different set of values. However, this construction currently requires the number of parameters to match the expected number, and them be in the exact same order as expected by the test method.

Since PHP 8.0 it is possible to pass argument by name to a method, which can be combined with array destructuring to allow passing arguments by name to a function. This would allow something like the very simple example below:

<?php declare(strict_types=1);
use PHPUnit\Framework\TestCase;

final class DataTest extends TestCase
{
    /**
     * @dataProvider additionProvider
     */
    public function testEquals(int $a, int $b = 0, int $expected = 0): void
    {
        $this->assertSame($expected, $a + $b);
    }

    public function additionProvider(): array
    {
        return [
            [0, 1, 1], // already works
            [0], // already works
            [1, 'b' => 3, 'expected' => 4], // already works (array keys are discarded)
            [1, 'expected' => 4, 'b' => 3], // does not work (as intended) yet
        ];
    }
}

I got my local testsuite to behave like this by removing the array_values call that is applied to the test arguments before running, i.e. changing

phpunit/src/Framework/TestCase.php

Line 1016 in a066359

$testResult = $this->{$this->name}(...array_values($testArguments));

to

            $testResult = $this->{$this->name}(...$testArguments); 

but I'm not sure of possible consequences elsewhere, so have not yet found time to make a proper PR yet.

Edit: it seems that the array_values call is actually required to make dependencyInput function properly; if I change

phpunit/src/Framework/TestCase.php

Line 1011 in a066359

$testArguments = array_merge($this->data, $this->dependencyInput);

to

            $testArguments = array_merge($this->data, array_values($this->dependencyInput)); 

all existing tests seem to pass locally as before.