LehrerApp/LehrerApp.Tests/AppLoggerTests.cs

using LehrerApp.Core.Services;
using Xunit;

namespace LehrerApp.Tests;

public sealed class AppLoggerTests
{
    [Fact]
    public void Konstruktor_LegtLogVerzeichnisAn()
    {
        using var temp = new TempAppData();

        _ = new AppLogger(temp.Path);

        Assert.True(Directory.Exists(Path.Combine(temp.Path, "logs")));
    }

    [Fact]
    public void Info_SchreibtZeileInDieHeutigeLogdatei()
    {
        using var temp = new TempAppData();
        var logger = new AppLogger(temp.Path);

        logger.Info("Anwendung gestartet.");

        var expectedFile = Path.Combine(temp.Path, "logs", $"lehrerapp-{DateTime.Now:yyyy-MM-dd}.log");
        Assert.True(File.Exists(expectedFile));
        var content = File.ReadAllText(expectedFile);
        Assert.Contains("[INFO ]", content);
        Assert.Contains("Anwendung gestartet.", content);
    }

    [Fact]
    public void Error_MitException_SchreibtStapelverfolgungMit()
    {
        using var temp = new TempAppData();
        var logger = new AppLogger(temp.Path);

        try { throw new InvalidOperationException("Testfehler"); }
        catch (Exception ex) { logger.Error("Etwas ist schiefgelaufen.", ex); }

        var content = File.ReadAllText(Path.Combine(temp.Path, "logs", $"lehrerapp-{DateTime.Now:yyyy-MM-dd}.log"));
        Assert.Contains("[ERROR]", content);
        Assert.Contains("Testfehler", content);
        Assert.Contains("InvalidOperationException", content);
    }

    [Fact]
    public void MehrereEintraege_WerdenAlleAngehaengt()
    {
        using var temp = new TempAppData();
        var logger = new AppLogger(temp.Path);

        logger.Info("Erster Eintrag");
        logger.Warn("Zweiter Eintrag");
        logger.Error("Dritter Eintrag");

        var lines = File.ReadAllLines(Path.Combine(temp.Path, "logs", $"lehrerapp-{DateTime.Now:yyyy-MM-dd}.log"));
        Assert.Equal(3, lines.Length);
    }

    [Fact]
    public void Konstruktor_LoeschtLogdateienAelterAlsDieAufbewahrungsfrist()
    {
        using var temp = new TempAppData();
        var logDir = Path.Combine(temp.Path, "logs");
        Directory.CreateDirectory(logDir);

        var oldFile = Path.Combine(logDir, "lehrerapp-2000-01-01.log");
        var recentFile = Path.Combine(logDir, $"lehrerapp-{DateTime.Now:yyyy-MM-dd}.log");
        File.WriteAllText(oldFile, "alt");
        File.WriteAllText(recentFile, "aktuell");
        File.SetLastWriteTime(oldFile, DateTime.Now.AddDays(-30));

        _ = new AppLogger(temp.Path);

        Assert.False(File.Exists(oldFile));
        Assert.True(File.Exists(recentFile));
    }

    [Fact]
    public void Konstruktor_BehaeltLogdateienInnerhalbDerAufbewahrungsfrist()
    {
        using var temp = new TempAppData();
        var logDir = Path.Combine(temp.Path, "logs");
        Directory.CreateDirectory(logDir);

        var recentButOldFile = Path.Combine(logDir, "lehrerapp-recent.log");
        File.WriteAllText(recentButOldFile, "vor 5 Tagen");
        File.SetLastWriteTime(recentButOldFile, DateTime.Now.AddDays(-5));

        _ = new AppLogger(temp.Path);

        Assert.True(File.Exists(recentButOldFile));
    }

    private sealed class TempAppData : IDisposable
    {
        public string Path { get; } = System.IO.Path.Combine(
            System.IO.Path.GetTempPath(), $"lehrerapp-logger-tests-{Guid.NewGuid():N}");

        public TempAppData() => Directory.CreateDirectory(Path);
        public void Dispose() { if (Directory.Exists(Path)) Directory.Delete(Path, recursive: true); }
    }
}