ModuleService { public boolean isModuleEnabled(String module) { if (module == null) { throw new IllegalArgumentException("Module name should be set"); } return true; }  boolean isModuleEnabled(String module);  }
@Test(expected = IllegalArgumentException.class) public void nullParameterShouldThrowException() { moduleService.isModuleEnabled(null); }
@Test public void allValuesShouldBeOkForNow() { assertTrue(moduleService.isModuleEnabled("ok")); }