BinaryJoiningExpressionImpl implements JoiningExpression<T> { @Override public CharSequence prefix() { return prefix; } BinaryJoiningExpressionImpl(
            final CharSequence separator,
            final CharSequence prefix,
            final CharSequence suffix,
            final ToString<T> first,
            final ToString<T> second); @Override List<ToString<T>> expressions(); @Override CharSequence prefix(); @Override CharSequence suffix(); @Override CharSequence separator(); @Override String apply(T object);  }
@Test void prefix() { assertEquals(PREFIX, instance.prefix()); }