CountingLinesTests.cs

namespace Easy.Common.Tests.Unit.StreamExtensions;

using Easy.Common.Extensions;
using NUnit.Framework;
using Shouldly;
using System;
using System.IO;
using System.Text;

[TestFixture]
internal sealed class CountingLinesTests
{
    [Test]
    public void When_processing_null_stream()
    {
        Should.Throw<NullReferenceException>(() => ((MemoryStream) null).CountLines())
            .Message.ShouldBe("Object reference not set to an instance of an object.");
    }

    [Test]
    public void When_processing_empty_stream()
    {
        using var mem = new MemoryStream();
        mem.CountLines().ShouldBe(0);
    }
        
    [TestCase("\r")]
    [TestCase("\n")]
    [TestCase("\r\n")]
    public void When_processing_stream_with_empty_line(string content)
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes(content);
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(1, $"Content was: '{content}'");
    }

    [TestCase("\r\r")]
    [TestCase("\n\n")]
    [TestCase("\r\n\r\n")]
    public void When_processing_stream_with_empty_lines(string content)
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes(content);
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(2, $"Content was: '{content}'");
    }

    [TestCase("A")]
    [TestCase("A\r")]
    [TestCase("A\n")]
    [TestCase("A\r\n")]
    public void When_processing_stream_with_single_line(string content)
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes(content);
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(1, $"Content was: '{content}'");
    }

    [Test]
    public void When_processing_stream_with_utf16_characters()
    {
        byte[] bytes = Encoding.BigEndianUnicode.GetBytes(" ਊ ");
        using var stream = new MemoryStream(bytes);
        stream.CountLines(Encoding.BigEndianUnicode).ShouldBe(1);
    }

    [Test]
    public void When_processing_stream_with_lines_terminated_by_carriage_return()
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes("A\rB\r\r");
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(3);
    }

    [Test]
    public void When_processing_stream_with_lines_terminated_by_new_line()
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes("A\nB\n\n");
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(3);
    }

    [Test]
    public void When_processing_stream_with_lines_terminated_by_carriage_return_followed_by_new_line()
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes("A\r\nB\r\n\r\n");
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(3);
    }

    [Test]
    public void When_processing_long_line_terminated_by_carriage_return()
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes($"A\r{new string('_', 1_500_000)}\rB");
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(3);
    }

    [Test]
    public void When_processing_long_line_terminated_by_carriage_by_new_line()
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes($"A\n{new string('_', 1_500_000)}\nB");
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(3);
    }

    [Test]
    public void When_processing_long_line_terminated_by_carriage_return_followed_by_new_line()
    {
        using var mem = new MemoryStream();
        var input = Encoding.UTF8.GetBytes($"A\r\n{new string('_', 1_500_000)}\r\nB");
        mem.Write(input, 0, input.Length);
        mem.Position = 0;

        mem.CountLines().ShouldBe(3);
    }

    [Test]
    public void When_processing_a_ascii_file()
    {
        FileInfo file = null;
        try
        {
            file = new FileInfo(Path.GetTempFileName());
            using(var writer = new StreamWriter(File.OpenWrite(file.FullName), Encoding.ASCII))
            {
                writer.WriteLine("A");
                writer.WriteLine("B");
                writer.WriteLine("❤");
                writer.WriteLine("C");
            }

            using (var stream = file.OpenRead())
            {
                stream.CountLines().ShouldBe(4);
            }
        } finally
        {
            file?.Delete();
        }
    }

    [Test]
    public void When_processing_a_utf8_file()
    {
        FileInfo file = null;
        try
        {
            file = new FileInfo(Path.GetTempFileName());
            using(var writer = new StreamWriter(File.OpenWrite(file.FullName), Encoding.UTF8))
            {
                writer.WriteLine("A");
                writer.WriteLine("B");
                writer.WriteLine("C");
            }

            using (var stream = file.OpenRead())
            {
                stream.CountLines().ShouldBe(3);
            }
        } finally
        {
            file?.Delete();
        }
    }

    [Test]
    public void When_processing_a_utf7_file()
    {
        FileInfo file = null;
        try
        {
            file = new FileInfo(Path.GetTempFileName());
#pragma warning disable SYSLIB0001
#pragma warning disable CS0618
            using(var writer = new StreamWriter(File.OpenWrite(file.FullName), Encoding.UTF7))
#pragma warning restore CS0618
#pragma warning restore SYSLIB0001
            {
                writer.WriteLine("A");
                writer.WriteLine("B");
                writer.WriteLine("C");
            }

            using (var stream = file.OpenRead())
            {
                stream.CountLines().ShouldBe(3);
            }
        } finally
        {
            file?.Delete();
        }
    }

    [Test]
    public void When_processing_a_utf16_file()
    {
        FileInfo file = null;
        try
        {
            file = new FileInfo(Path.GetTempFileName());
            using(var writer = new StreamWriter(File.OpenWrite(file.FullName), Encoding.Unicode))
            {
                writer.WriteLine("A");
                writer.WriteLine("B");
                writer.WriteLine("C");
            }

            using (var stream = file.OpenRead())
            {
                stream.CountLines().ShouldBe(3);
            }
        } finally
        {
            file?.Delete();
        }
    }

    [Test]
    public void When_processing_a_utf32_file()
    {
        FileInfo file = null;
        try
        {
            file = new FileInfo(Path.GetTempFileName());
            using(var writer = new StreamWriter(File.OpenWrite(file.FullName), Encoding.UTF32))
            {
                writer.WriteLine("A");
                writer.WriteLine("B");
                writer.WriteLine("C");
            }

            using (var stream = file.OpenRead())
            {
                stream.CountLines().ShouldBe(3);
            }
        } finally
        {
            file?.Delete();
        }
    }
}