@Test public void registeringSameObjectTwiceFails() {
    StringCatcher catcher = new StringCatcher();
    bus.register(catcher);
    try {
      bus.register(catcher);
      fail();
    } catch (IllegalArgumentException e) {
      assertEquals("Object already registered.", e.getMessage());
    }
  }
Test case for {@link Bus}.

@author Cliff Biffle
otto/src/test/java/com/squareup/otto/BusTest.java