Add PHPStan integration (blog post)

docs/blog/2024-06-21-phpstan-integration.md

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+---
+date: '2024-06-21'
+title: 'PHPStan integration'
+description: 'What a milestone! We finally made it into helping our friends from PHPStan. They started integrating bashunit in their end-to-end tests, which ended up creating a new feature, adding new assertions and improving multiline string comparisons.'
+coverUrl: '/covers/2024-06-21-phpstan-integration.jpg'
+coverAlt: 'bashunit integrated into PHPStan'
+
+aside: false
+---
+
+# {{ $frontmatter.title }}
+
+<time>{{ $formatDate($frontmatter.date) }}</time>
+
+{{ $frontmatter.description }}
+
+<img :src="$frontmatter.coverUrl" :alt="$frontmatter.coverAlt" width="100%">
+
+**TL;DR**: From now on, you can run bashunit assertions [standalone](/standalone) (without a test context), a new [assert_line_count](/assertions#assert-line-count) function, and improved multiline-string comparison.
+
+---
+
+Earlier this week, [PHPStan](https://phpstan.org/) started integrating `bashunit` in their **e2e tests** ([PR](https://github.com/phpstan/phpstan-src/pull/3160)).
+
+However, they didn't want to use bashunit test runner, instead they were interested only in the **assert functions** standalone of the core library ([Issue](https://github.com/TypedDevs/bashunit/issues/257)).
+
+> "Basically we want to use the nice assertions syntax of bashunit not to unit tests bash functions, but to end-to-end tests executables." `@ondrejmirtes`
+
+This wasn't something that bashunit supported (yet), so `@staabm` created a [custom script](https://github.com/phpstan/phpstan-src/pull/3160#discussion_r1641646749) to allow this. That was the beginning of an intense couple of days discovering together how to implement bashunit in such a big existing system, and a motivation for us to support this feature natively from `bashunit` - which means, an optimized script and feature from within the library.
+
+Here is an example of the [result](https://github.com/phpstan/phpstan-src/pull/3160/files#diff-194218c48b9a0cdd03974145733804c2d992ca818529fe2fa69a501d8b5b1cc3L197) of how they finally implemented bashunit:
+
+```diff
+- [ $(echo "$OUTPUT" | wc -l) -eq 1 ]
+- grep 'Method TraitsCachingIssue\\TestClassUsingTrait::doBar() should return stdClass but returns Exception.' <<< "$OUTPUT"
++ ../bashunit -a line_count 1 "$OUTPUT"
++ ../bashunit -a contains 'Method TraitsCachingIssue\TestClassUsingTrait::doBar() should return stdClass but returns Exception.' "$OUTPUT"
+```
+
+`./bashunit -a|--assert [...args]` allows you to call any [assertion](/assertions) outside the test runner, which means you can run them [standalone](/standalone).
+
+Additionally, we discovered that multiline string comparison didn't work as expected, so we fixed that. And `@staabm` helped us adding a new assert function to check the number of lines within a string.