First possible test for legacy-wav-report exercise

ExcludeFilesTest.cs

public class ExcludeFilesTest
{
    [Test]
    public void Exclude_File_With_Keyword()
    {
        var wavExtractor = Substitute.For<WavExtractor32V>();
        var excludeFiles = new ExcludeFiles(wavExtractor);

        var filenames = new List<string>()
        {
            "file1.wav",
            "fileWithKeyword.wav",
            "file1.wav",
        };
        var optional = new List<string>()
        {
            "exclude=Keyword"
        };
        excludeFiles.Execute(filenames, optional);

        var expectedFiles = new List<string>()
        {
            "file1.wav",
            "file1.wav",
        };
        wavExtractor.Received().Execute(
            Arg.Is<List<string>>(x => x.SequenceEqual(expectedFiles)),
            Arg.Is<List<string>>(x => x.SequenceEqual(optional))
        );
    }
}

public class ExcludeFiles : WavExtractor32V
{
    private readonly WavExtractor32V _wavExtractor;

    public ExcludeFiles(WavExtractor32V wavExtractor)
    {
        _wavExtractor = wavExtractor;
    }

    public override void Execute(List<string> filenames, List<string> optional)
    {
        var keyword = optional.First().Split("=").Last();
        var filteredFiles = filenames.FindAll(x => !x.Contains(keyword)).ToList();
        _wavExtractor.Execute(filteredFiles, optional);
    }
}