code: private function findFixtures(array $fixtures = [])
      {
          $fixturesPath = $this->getFixturePath();
  
          $filesToSearch = ['*Fixture.php'];
          $findAll = ($fixtures === []);
  
          if (!$findAll) {
              $filesToSearch = [];
  
              foreach ($fixtures as $fileName) {
                  $filesToSearch[] = $fileName . 'Fixture.php';
              }
          }
  
          $files = FileHelper::findFiles($fixturesPath, ['only' => $filesToSearch]);
          $foundFixtures = [];
  
          foreach ($files as $fixture) {
              $foundFixtures[] = $this->getFixtureRelativeName($fixture);
          }
  
          return $foundFixtures;
      }
docs: Finds fixtures to be loaded, for example "User", if no fixtures were specified then all of them
  will be searching by suffix "Fixture.php".
  @param array $fixtures fixtures to be loaded
  @return array Array of found fixtures. These may differ from input parameter as not all fixtures may exists.