### Question:
PromptSupport { public static void setBackground(Color background, JTextComponent textComponent) { TextUIWrapper.getDefaultWrapper().install(textComponent, true); textComponent.putClientProperty(BACKGROUND, background); textComponent.repaint(); } private  PromptSupport(); static void init(String promptText, Color promptForeground, Color promptBackground,
			final JTextComponent textComponent); static FocusBehavior getFocusBehavior(JTextComponent textComponent); static void setFocusBehavior(FocusBehavior focusBehavior, JTextComponent textComponent); static String getPrompt(JTextComponent textComponent); static void setPrompt(String promptText, JTextComponent textComponent); static Color getForeground(JTextComponent textComponent); static void setForeground(Color promptTextColor, JTextComponent textComponent); static Color getBackground(JTextComponent textComponent); static void setBackground(Color background, JTextComponent textComponent); @SuppressWarnings("unchecked") static Painter<? super T> getBackgroundPainter(T textComponent); static void setBackgroundPainter(Painter<? super T> background, T textComponent); static void setFontStyle(Integer fontStyle, JTextComponent textComponent); static Integer getFontStyle(JTextComponent textComponent); static final String PROMPT; static final String FOREGROUND; static final String BACKGROUND; static final String BACKGROUND_PAINTER; static final String FOCUS_BEHAVIOR; static final String FONT_STYLE; }### Answer:
@Test public void testSetBackground() throws Exception { PromptSupport.setBackground(Color.RED, txt); assertEquals(Color.RED, PromptSupport.getBackground(txt)); assertEquals(Color.RED, txt.getClientProperty(PromptSupport.BACKGROUND)); promptSupportMustStayInstalled(); }