public void copy(final IntHashSet that)
    {
        if (values.length != that.values.length)
        {
            throw new IllegalArgumentException("cannot copy object: masks not equal");
        }

        System.arraycopy(that.values, 0, values, 0, values.length);
        this.sizeOfArrayValues = that.sizeOfArrayValues;
        this.containsMissingValue = that.containsMissingValue;
    }
@Test
    void copiesOtherIntHashSet()
    {
        addTwoElements(testSet);

        final IntHashSet other = new IntHashSet(100);
        other.copy(testSet);

        assertContainsElements(other);
    }