public async Task FindFile_FromRoot(string input, string expectedFilePath)
        {
            var inputTree = ProjectTreeParser.Parse(input);

            var projectTreeService  = IProjectTreeServiceFactory.Create(inputTree);
            var sourceItemsProvider = IProjectItemProviderFactory.Create();
            var fileSystem          = IFileSystemFactory.Create(path => true);

            var provider = new AppConfigFileSpecialFileProvider(projectTreeService, sourceItemsProvider, null, fileSystem);

            var filePath = await provider.GetFileAsync(SpecialFiles.AppConfig, SpecialFileFlags.FullPath);

            Assert.Equal(expectedFilePath, filePath);
        }
        public async Task CreateFile_InRootFolder(string input, string expected, string expectedFilePath)
        {
            var inputTree    = ProjectTreeParser.Parse(input);
            var expectedTree = ProjectTreeParser.Parse(expected);

            var projectTreeService  = IProjectTreeServiceFactory.Create(inputTree);
            var sourceItemsProvider = IProjectItemProviderFactory.CreateWithAdd(inputTree);
            var fileSystem          = IFileSystemFactory.Create(path => false,
                                                                path =>
            {
                // Verify that file is created on disk.
                Assert.Equal(expectedFilePath, path);
                return(null);
            });

            var provider = new AppConfigFileSpecialFileProvider(projectTreeService, sourceItemsProvider, null, fileSystem);
            var filePath = await provider.GetFileAsync(SpecialFiles.AppConfig, SpecialFileFlags.CreateIfNotExist);

            Assert.Equal(expectedFilePath, filePath);
            AssertAreEquivalent(expectedTree, inputTree);
        }