public void TypeNotHashSet()
        {
            var comparer = new HashSetsComparer <string>(new ComparisonSettings(), null, null);
            var obj1     = new HashSet <string>();
            var obj2     = new HashSet <string>();

            Assert.Throws <ArgumentException>(() => comparer.Compare(typeof(int), obj1, obj2));
        }
        public void SecondParameterNotEnumerable()
        {
            var comparer = new HashSetsComparer <string>(new ComparisonSettings(), null, null);
            var obj1     = new HashSet <string>();
            var obj2     = new A();

            Assert.Throws <ArgumentException>(() => comparer.Compare(typeof(HashSet <string>), obj1, obj2));
        }