
using Xunit;
using Xunit;
namespace ConsoleApp {
    public class ProgramTests {
        [Fact(DisplayName = "Uppercase letters are shifted correctly and wrap from Z to A")]
        public void CaesarCipherEncode_ShiftsUppercaseCorrectly()
        {
            Assert.Equal("KHOOR, ZRUOG!", Program.CaesarCipherEncode("HELLO, WORLD!", 3));
            Assert.Equal("ABC", Program.CaesarCipherEncode("XYZ", 3));
            Assert.Equal("XYZ", Program.CaesarCipherEncode("XYZ", 0));
        }

        [Fact(DisplayName = "Lowercase letters are shifted correctly and wrap from z to a")]
        public void CaesarCipherEncode_ShiftsLowercaseCorrectly()
        {
            Assert.Equal("def", Program.CaesarCipherEncode("abc", 3));
            Assert.Equal("abc", Program.CaesarCipherEncode("abc", 0));
            Assert.Equal("abc", Program.CaesarCipherEncode("xyz", 3));
        }

        [Fact(DisplayName = "Non-letter characters remain unchanged in output")]
        public void CaesarCipherEncode_NonLettersUnchanged()
        {
            Assert.Equal("Czggj, Rjmgy!", Program.CaesarCipherEncode("Hello, World!", -5));
            Assert.Equal("abc 123!", Program.CaesarCipherEncode("abc 123!", 0));
            Assert.Equal("123!@#", Program.CaesarCipherEncode("123!@#", 10));
        }

        [Fact(DisplayName = "Case is preserved in output string")]
        public void CaesarCipherEncode_PreservesCase()
        {
            Assert.Equal("Czggj, Rjmgy!", Program.CaesarCipherEncode("Hello, World!", -5));
            Assert.Equal("CDE zab", Program.CaesarCipherEncode("ABC xyz", 2));
        }

        [Fact(DisplayName = "Negative shift values shift in the opposite direction and wrap correctly")]
        public void CaesarCipherEncode_NegativeShift()
        {
            Assert.Equal("Rdbqds 123!", Program.CaesarCipherEncode("Secret 123!", -1));
            Assert.Equal("abc", Program.CaesarCipherEncode("def", -3));
        }

        [Fact(DisplayName = "Encoded string is returned by function")]
        public void CaesarCipherEncode_ReturnsEncodedString()
        {
            string result = Program.CaesarCipherEncode("Test", 1);
            Assert.Equal("Uftu", result);
        }
    }
}

ProgramTests.cs

Master the essentials of string manipulation, text parsing, and efficient text processing in C#. This course guides you from the basics of working with strings to advanced text analysis and formatting, using engaging real-world examples and hands-on challenges.

Explore the basics of strings in C#, including creation, concatenation, and essential properties. Practice manipulating and analyzing text with beginner-friendly challenges.

Advance your skills with string formatting, splitting, trimming, and replacing text. Tackle real-world parsing and formatting tasks.

Apply your string skills to analyze text, check for palindromes, perform frequency analysis, and implement basic ciphers.

Challenge: Caesar Cipher Encoder

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