### Question:
CollapsedDefinitionPaletteItemWidgetViewImpl implements CollapsedDefinitionPaletteItemWidgetView,
                                                                     IsElement { @EventHandler("icon") public void onMouseDown(final MouseDownEvent mouseDownEvent) { presenter.onMouseDown(mouseDownEvent.getClientX(), mouseDownEvent.getClientY(), mouseDownEvent.getX(), mouseDownEvent.getY()); } CollapsedDefinitionPaletteItemWidgetViewImpl(); @Inject  CollapsedDefinitionPaletteItemWidgetViewImpl(final Button icon,
                                                        final DOMGlyphRenderers domGlyphRenderers); @Override void init(final Presenter presenter); @Override void render(final Glyph glyph,
                       final double width,
                       final double height); @EventHandler("icon") void onMouseDown(final MouseDownEvent mouseDownEvent); @PreDestroy void destroy();  }### Answer:
@Test public void testMouseDownEvent() { this.view.onMouseDown(mouseDownEvent); verify(presenter).onMouseDown(eq(CLIENT_X), eq(CLIENT_Y), eq(X), eq(Y)); }