Should assertType always be inside a function or can it be on the top level?

[calebdw]

Hello!

Please see larastan/larastan#1876 (comment) for context.

Essentially should assertType never be on the top level due to performance issues?

For example, which of the following (if either) is more correct / performant?

<?php

namespace Test;

use function PHPStan\Testing\assertType;

/** @var ?string $v */
assertType('?string', $v);

or

<?php

namespace Test;

use function PHPStan\Testing\assertType;

function (?string $v) {
    assertType('?string', $v);
};

If there is a difference, should the docs be updated to reflect this? I couldn't find anything in the documentation.

Thanks!

[ondrejmirtes]

I don't think it's because of performance. There might have been some performance-related issue in the past that might have manifested in this case like sebastianbergmann/phpunit#5524 or sebastianbergmann/phpunit#5758 - essentially PHPUnit taking a long time because data returned by data provider contained huge objects. But that should be solved and shouldn't influence how tests look like.

But I see two different reasons to put assertType and similar in a non-root scope:

1. Historical: We used to use runtime reflection. Before static reflection (https://phpstan.org/blog/zero-config-analysis-with-static-reflection) there was a chance that calls below a class declaration would be executed in runtime. So we put everything in anonymous functions to prevent that. But runtime reflection is long gone from PHPStan (https://github.com/phpstan/phpstan/releases/tag/1.7.0) so this is no longer an issue.
2. Root scope is sometimes special. See: https://phpstan.org/r/8868a0a3-b815-45bf-b7fa-d1f0b97ae709 so in order to prevent any weirdness (and when actually not testing issues related to root scope) we tend to test everything in isolated scopes like that.