### Question:
Receptor extends Tileable { @Override public boolean accepts(Direction direction, Marble marble) { return !locked && !getSlot(direction).isOccupied(); }  void rotate(int turns); int getRotation(); Slot getSlot(Direction direction); boolean isMarked(); boolean isLocked(); void lock(); void unlock(); PowerUp getPowerUp(); void setPowerUp(PowerUp powerUp); @Override boolean isReleasable(Direction direction, Marble marble); @Override boolean allowsConnection(Direction direction); @Override boolean accepts(Direction direction, Marble marble); @Override void accept(Direction direction, Marble marble);  }### Answer:
@Test public void acceptsWhenSlotEmpty() { Receptor receptor = new Receptor(); assertThat(receptor.accepts(Direction.LEFT, marble)).isTrue(); }