public async Task Clear_should_return_if_folder_absent()
        {
            _directory.Exists(Arg.Any <string>()).Returns(false);

            await _cache.ClearAsync();

            _directory.DidNotReceive().GetFiles(Arg.Any <string>());
        }
        public async Task Clear_should_remove_all()
        {
            var fileSystem = new MockFileSystem();

            _cache = new DirectoryImageCache(_folderPath, 2, fileSystem);

            fileSystem.AddFile(Path.Combine(_folderPath, "*****@*****.**"), new MockFileData(""));
            fileSystem.AddFile(Path.Combine(_folderPath, "*****@*****.**"), new MockFileData(""));
            fileSystem.AllFiles.Count().Should().Be(2);

            await _cache.ClearAsync();

            fileSystem.AllFiles.Count().Should().Be(0);
        }
        public async void Clear_should_remove_all()
        {
            var fileSystem = new MockFileSystem();

            _cache = new DirectoryImageCache(FolderPath, 2, fileSystem);

            fileSystem.AddFile($"{FolderPath}\\[email protected]", new MockFileData(""));
            fileSystem.AddFile($"{FolderPath}\\[email protected]", new MockFileData(""));
            fileSystem.AllFiles.Count().Should().Be(2);

            await _cache.ClearAsync();

            fileSystem.AllFiles.Count().Should().Be(0);
        }