@Test public void shouldComputeIfAbsent() { final int testKey = 7; final int testValue = 7; final IntUnaryOperator function = (i) -> testValue; assertEquals(map.initialValue(), map.get(testKey)); assertThat(map.computeIfAbsent(testKey, function), is(testValue)); assertThat(map.get(testKey), is(testValue)); }