### Question:
ButtonGroupAdapter implements GriffonPivotAdapter, org.apache.pivot.wtk.ButtonGroupListener { public void buttonRemoved(org.apache.pivot.wtk.ButtonGroup arg0, org.apache.pivot.wtk.Button arg1) { if (buttonRemoved != null) { buttonRemoved.call(arg0, arg1); } }  CallableWithArgs<Void> getButtonAdded(); CallableWithArgs<Void> getButtonRemoved(); CallableWithArgs<Void> getSelectionChanged(); void setButtonAdded(CallableWithArgs<Void> buttonAdded); void setButtonRemoved(CallableWithArgs<Void> buttonRemoved); void setSelectionChanged(CallableWithArgs<Void> selectionChanged); void buttonAdded(org.apache.pivot.wtk.ButtonGroup arg0, org.apache.pivot.wtk.Button arg1); void buttonRemoved(org.apache.pivot.wtk.ButtonGroup arg0, org.apache.pivot.wtk.Button arg1); void selectionChanged(org.apache.pivot.wtk.ButtonGroup arg0, org.apache.pivot.wtk.Button arg1);  }### Answer:
@Test public void testButtonRemoved() { final boolean[] invoked = new boolean[1]; CallableWithArgs<Void> callable = new CallableWithArgs<Void>() { public Void call(Object... args) { invoked[0] = true; return null; } }; assertNull(adapter.getButtonRemoved()); adapter.buttonRemoved(null, null); assertFalse(invoked[0]); adapter.setButtonRemoved(callable); adapter.buttonRemoved(null, null); assertTrue(invoked[0]); }