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

        public static void AppendFormat(string original, IFormatProvider provider, string format, object[] values, string expected)
        {
            StringBuilder builder;
            if (values != null)
            {
                if (values.Length == 1)
                {
                    // Use AppendFormat(string, object) or AppendFormat(IFormatProvider, string, object)
                    if (provider == null)
                    {
                        // Use AppendFormat(string, object)
                        builder = new StringBuilder(original);
                        builder.AppendFormat(format, values[0]);
                        Assert.Equal(expected, builder.ToString());
                    }
                    // Use AppendFormat(IFormatProvider, string, object)
                    builder = new StringBuilder(original);
                    builder.AppendFormat(provider, format, values[0]);
                    Assert.Equal(expected, builder.ToString());
                }
                else if (values.Length == 2)
                {
                    // Use AppendFormat(string, object, object) or AppendFormat(IFormatProvider, string, object, object)
                    if (provider == null)
                    {
                        // Use AppendFormat(string, object, object)
                        builder = new StringBuilder(original);
                        builder.AppendFormat(format, values[0], values[1]);
                        Assert.Equal(expected, builder.ToString());
                    }
                    // Use AppendFormat(IFormatProvider, string, object, object)
                    builder = new StringBuilder(original);
                    builder.AppendFormat(provider, format, values[0], values[1]);
                    Assert.Equal(expected, builder.ToString());
                }
                else if (values.Length == 3)
                {
                    // Use AppendFormat(string, object, object, object) or AppendFormat(IFormatProvider, string, object, object, object)
                    if (provider == null)
                    {
                        // Use AppendFormat(string, object, object, object)
                        builder = new StringBuilder(original);
                        builder.AppendFormat(format, values[0], values[1], values[2]);
                        Assert.Equal(expected, builder.ToString());
                    }
                    // Use AppendFormat(IFormatProvider, string, object, object, object)
                    builder = new StringBuilder(original);
                    builder.AppendFormat(provider, format, values[0], values[1], values[2]);
                    Assert.Equal(expected, builder.ToString());
                }
            }
            // Use AppendFormat(string, object[]) or AppendFormat(IFormatProvider, string, object[])
            if (provider == null)
            {
                // Use AppendFormat(string, object[])
                builder = new StringBuilder(original);
                builder.AppendFormat(format, values);
                Assert.Equal(expected, builder.ToString());
            }
            // Use AppendFormat(IFormatProvider, string, object[])
            builder = new StringBuilder(original);
            builder.AppendFormat(provider, format, values);
            Assert.Equal(expected, builder.ToString());
        }