I'm using psalm-vscode-plugin v1.2.2 with vs-code 1.52.1 / 1.53.0 (and code-server 3.8.1) and tried to get auto-complete working for phpunit 9.5.2 (loaded as composer library). E.g. $this->assertTrue() cannot be autocompleted from PHPUnit\Framework\TestCase -> PHPUnit\Framework\Assert.
When I type $this->assertTrue() manually, detecting invalid parameters works.

I'm not sure it's related to psalm-vscode-plugin or psalm itself, so I also reported this in psalm/psalm-vscode-plugin#34 .

Happens with psalm 4.4.1 and psalm 4.5.1