Phpactor will work by default with any project which uses composer in a standard way. Some platforms (e.g. Drupal 8) will need more attention, additionally there are various extensions which can be installed to integrate with specific tooling.
The behat extension provides completion and goto definition support.
The PHPSpec extension provides subject-under-test member completion.
The PHPUnit extension provides test class generation and type inference.
See the Drupal 8 guide.