@Test public void checkAMessage() { // Setup String result = null; String expectedException = "Unable to find a Locale specific resource file to bind with i18n interface 'com.octo.gwt.test.i18n.MyMessages' and there is no @DefaultXXXValue annotation on 'a_message' called method"; // Test 1 try { result = messages.a_message("Gael", 23, true); Assert.fail( "The test is expected to throw an execption since 'a_message' can't be retrieve in the default property file and no @DefaultMessage is set on the method"); } catch (Exception e) { Assert.assertEquals(expectedException, e.getMessage()); } // Setup 2 GwtConfig.setLocale(Locale.FRANCE); // Test 2 result = messages.a_message("Gael", 23, true); // Assert2 Assert.assertEquals("Bonjour Gael, vous avez saisi le nombre 23 et le booléen true", result); }