### Question:
GetSystemPropertyAction implements PrivilegedAction<String> { public String run() { return System.getProperty(key); } GetSystemPropertyAction(String key); String run();  }### Answer:
@Test public void testRun() throws Exception { System.setProperty(FOO, BAR); try { assertThat(new GetSystemPropertyAction(FOO).run(), is(BAR)); } finally { System.clearProperty(FOO); } }