psalm/tests/SelfOutTest.php

<?php
namespace Psalm\Tests;

class ReferenceConstraintTest extends TestCase
{
    use Traits\ValidCodeAnalysisTestTrait;

    /**
     * @return iterable<string,array{string,assertions?:array<string,string>,error_levels?:string[]}>
     */
    public function providerValidCodeParse()
    {
      return [
          'changeInterface' => [
              '<?php
                  interface Foo {
                      /**
                       * @return void
                       */
                      public function far() {
                      }
                  }
                  class Bar {
                      /**
                       * @psalm-self-out Foo
                       * @return void
                       */
                      public function baz() {
                      }
                  }
                  $bar = new Bar();
                  $bar->baz();
                  $bar->far();
                  '
          ]
      ];
    }
}