Current test methods:
testPacman_initial() - tests Pacman initialization
testGhost_initial() - tests Ghost initialization
testRestart() - tests that game is reinitialized in terms of PacmanActor
testPacman_node() - tests that PacmanActor can change GridNode positions
testGhost_node() - tests that GhostActor can change GridNode positions
testPacman_death() - tests that PacmanActor is killed according to GridNode