README

Makes Psalm understand Pest test files.

$this in test closures. Pest binds every test(), it(), beforeEach() and afterEach() closure to a TestCase, so $this->user or $this->actingAs() is valid code. Pest documents that binding only as @param-closure-this TestCall, which Psalm 6.19+ reads literally: every $this->... in a test becomes UndefinedThisPropertyFetch or UndefinedMethod on TestCall, plus a Mixed* cascade. The plugin binds $this to the class Pest actually uses.
Pest's public API. Pest marks the classes behind expect()->toBe(), uses()->in(), pest()->extend() and test()->group() as @internal. The plugin stops reporting InternalMethod on them. Pest classes outside that API keep reporting.

Installation

composer require --dev alies-dev/psalm-plugin-pest
vendor/bin/psalm-plugin enable alies-dev/psalm-plugin-pest

Requirements: PHP 8.3+ (Pest 4's floor), Psalm 6.19+ or 7, Pest 4. Your test directory must be part of <projectFiles>.

For each test file, first match wins:

The class passed to uses(...) or pest()->extend(...) in the test file itself.
The class assigned to the file's directory through uses(...)->in(...) or pest()->extend(...)->in(...) in tests/Pest.php, or in any other file Pest loads at boot: tests/Helpers.php, tests/Expectations.php, the tests/Helpers/ and tests/Expectations/ trees, every Datasets.php, and every file under a Datasets/ directory. in() accepts string literals, globs, __DIR__ and __DIR__ . '/Feature'.
PHPUnit\Framework\TestCase, Pest's default, for files inside tests/.

Traits passed to uses() never decide the class. The files are parsed, never executed.

When the answer is uncertain the plugin keeps Pest's own TestCall binding rather than guess.

tests/Pest.php is looked up next to your Psalm config. A custom test directory (Pest's --test-directory) is not detected, and its tests keep Pest's binding.
A test file outside tests/ (for example a monorepo package with its own suite) keeps Pest's binding.
A boot file the plugin cannot read statically disables resolution for the whole suite. That covers a variable argument, a call inside a condition or a closure, an include, a top-level return or exit, an aliased use function uses, and a symlinked file.
uses()->in() written in one test file to configure other files is ignored.
Analyzing a single test file on its own declines when its TestCase class was not scanned; full project runs are unaffected.
Properties a test assigns dynamically ($this->user = ... in beforeEach()) are reported, because Psalm now sees the real TestCase. Declare them on the TestCase.
Psalm 7.0.0-beta22 has no @param-closure-this support, so there $this in a test closure is still InvalidScope. Binding activates automatically on a Psalm 7 release that carries it (vimeo/psalm master does). The InternalMethod relief works on every supported version.
Pest 5 is untested. The plugin keys on Pest's @param-closure-this TestCall tag and class names, and does nothing if those change.

MIT, see LICENSE.