System.Text.RegularExpressions.Tests.GroupCollectionTests.Item_Invalid C# (CSharp) Method

        public static void Item_Invalid(int groupNumber)
        {
            Regex regex = new Regex(@"(?<A1>a*)(?<A2>b*)(?<A3>c*)");
            GroupCollection groups = regex.Match("aaabbccccccccccaaaabc").Groups;

            Group group = groups[groupNumber];
            Assert.Same(string.Empty, group.Value);
            Assert.Equal(0, group.Index);
            Assert.Equal(0, group.Length);
            Assert.Equal(0, group.Captures.Count);
        }