### Question:
Pair { @Override public String toString() { return String.format("[%s = %s]", first, second); } Pair(F first, S second); @Override int hashCode(); @Override boolean equals(Object o); @Override String toString(); final F first; final S second; }### Answer:
@Test public void stringifying() { assertEquals("[1 = 2]", new Pair<>(1, 2).toString()); }