System.Text.Tests.StringBuilderTests.Append_CharArray C# (CSharp) Method

        public static void Append_CharArray(string original, char[] value, int startIndex, int charCount, string expected)
        {
            StringBuilder builder;
            if (startIndex == 0 && charCount == (value?.Length ?? 0))
            {
                // Use Append(char[])
                builder = new StringBuilder(original);
                builder.Append(value);
                Assert.Equal(expected, builder.ToString());
            }
            // Use Append(char[], int, int)
            builder = new StringBuilder(original);
            builder.Append(value, startIndex, charCount);
            Assert.Equal(expected, builder.ToString());
        }