### Question:
NiftyMouseImpl implements NiftyMouse { @Nullable @Override public String getCurrentId() { return currentId; } NiftyMouseImpl(
      @Nonnull final RenderDevice renderDevice,
      @Nonnull final InputSystem inputSystem,
      @Nonnull final TimeProvider timeProvider); @Override void registerMouseCursor(
      @Nonnull final String id,
      @Nonnull final String filename,
      final int hotspotX,
      final int hotspotY); @Nullable @Override String getCurrentId(); @Override void unregisterAll(); @Override void resetMouseCursor(); @Override void enableMouseCursor(@Nullable final String id); @Override void setMousePosition(final int x, final int y); @Override int getX(); @Override int getY(); @Override long getNoMouseMovementTime(); void updateMousePosition(final int x, final int y);  }### Answer:
@Test public void testGetCurrentMouseCursorDefaults() { replay(renderDeviceMock); assertNull(niftyMouse.getCurrentId()); }