@Test
public void shouldRaiseExceptionThatContainsValueOnlyIfNotASimpleDateFormat() {

    thrown.expect( ValueConversionException.class );
    thrown.expectMessage( "asdf" );
    thrown.expectMessage( not( containsString( notASimpleDateFormat.toString() ) ) );
    new DateConverter( notASimpleDateFormat ).convert( "asdf" );
}