Unify structure for ext/random's engine tests

[TimWolla]

This PR makes a sweeping change across all tests in ext/random/tests/02_engine to achieve a uniform appearance:

• Use a descriptive test title.
• Import all classes with use to reduce the visual noise within the test for repeated references to specific classes.
• Do not use the backslash in front of function calls for consistency with tests elsewhere.
• Do not use anonymous classes to give each engine a descriptive name.
• Use echo $e->getMessage(), PHP_EOL; with a comma to dump error messages.
• Use var_dump() to output engine values.
• Use 10_000 as the consistent number of verification iterations, instead of 1000, 5000 and 10000.
• Remove the Xoshiro128++ userland engine, because it does not really test ext/random, but rather PHP's bit fiddling capabilities.

[zeriyoshi]

I was thinking of a form like the first PR, where the implemented class name is defined in a separate file and iterated over. e.g.) engines.inc.
https://github.com/zeriyoshi/php-src/blob/ed42ae2c2fe30ad9e608b6e693cd3ef3c60f1d85/ext/random/tests/number_generator/common.inc

[TimWolla]

I find this not as readable, because one needs to keep the contents of the include file in the head, instead of simply reading the test from top to bottom.

[zeriyoshi]

Everything is in place, and you've properly corrected the sloppy test I wrote! Excellent!

Just one thing: the userland PRNG implementation probably needs to be tested. Other than this point, I think other is a trivial issue.

[zeriyoshi]

(I admit, in all honesty, that my initial testing was messy. Repeated implementation changes made tracking cumbersome and messy. You should originally create appropriate tests before proceeding with the implementation. Please do not imitate me!)

[TimWolla]

Just one thing: the userland PRNG implementation probably needs to be tested. Other than this point, I think other is a trivial issue.

As you already resolved the comment yourself: Is this still relevant? We could add it as a randomizer test, where the engine will actually need to interact with ext/random.

[zeriyoshi]

@TimWolla
I was not used to using GH and was operating it in a strange way...

How about using 64-bit PRNGs (PCG, Xoshiro) but adding a user-defined RNG as a test that forces truncation to 32-bit length?

<?php

use Random\Randomizer;
use Random\Engine;
use Random\Engine\Xoshiro256StarStar;

$randomizer = new Randomizer(
    new class implements Engine
    {
        private readonly Xoshiro256StarStar $engine;

        public function __construct()
        {
            $this->engine = new Xoshiro256StarStar();
        }

        public function generate(): string
        {
            return substr($this->engine->generate(), -4 /* char(8-bit) * 4 = 32-bit */);
        }
    }
);
// ~~~~

[zeriyoshi]

Suggested changes may be better served by another Pull Request
LGTM

[TimWolla]

@zeriyoshi I'm currently on vacation and will look into this again next week. It's not urgent anyway.

[TimWolla]

As you approved, I'll merge this now. I'll create a follow-up PR for the Randomizer tests and add a real-world user-engine to those then (e.g. Xoshiro128++).

[zeriyoshi]

I have been busy for a while and could not respond. Sorry about that.

It may not be possible to react much until early September.

Thank you for your work!