GitIgnoreMatcher Class

using var rootDirectory = TemporaryDirectory.Create();
rootDirectory.CreateTextFile(".gitignore", "*.log\n");
rootDirectory.CreateTextFile("src/.gitignore", "bin/\n!important.log\n");
rootDirectory.CreateEmptyFile("src/Program.cs");
rootDirectory.CreateEmptyFile("src/bin/App.dll");
rootDirectory.CreateEmptyFile("src/trace.log");
rootDirectory.CreateEmptyFile("src/important.log");

var matcher = new GitIgnoreMatcher(rootDirectory.FullPath);

// The .gitignore file of a directory applies to its content, and takes precedence over the parent ones
Assert.True(matcher.IsIgnored("src/trace.log"));
Assert.False(matcher.IsIgnored("src/important.log"));

// Enumerate the files that are not ignored. The enumeration does not go into src/bin.
var files = matcher.EnumerateFiles()
    .Select(path => Path.GetRelativePath(rootDirectory.FullPath, path).Replace('\\', '/'))
    .Order(StringComparer.Ordinal)
    .ToList();

Assert.Equal([".gitignore", "src/.gitignore", "src/Program.cs", "src/important.log"], files);