static async Task <Tuple <string, string> > ExtractDiffFiles(
string baseSha, object baseFileContent, string headSha, object headFileContent, string mergeBaseSha, object mergeBaseFileContent,
string fileName, bool checkedOut, string repoDir = "repoDir", string headRef = "headRef", string baseRef = "baseRef")
{
var repositoryModel = Substitute.For <ILocalRepositoryModel>();
repositoryModel.LocalPath.Returns(repoDir);
var pullRequest = Substitute.For <IPullRequestModel>();
pullRequest.Number.Returns(1);
pullRequest.Base.Returns(new GitReferenceModel(baseRef, "label", baseSha, "uri"));
pullRequest.Head.Returns(new GitReferenceModel("ref", "label", headSha, "uri"));
var serviceProvider = Substitutes.ServiceProvider;
var gitClient = MockGitClient();
var gitService = serviceProvider.GetGitService();
var service = new PullRequestService(gitClient, gitService, serviceProvider.GetOperatingSystem(), Substitute.For <IUsageTracker>());
gitClient.GetPullRequestMergeBase(Arg.Any <IRepository>(), Arg.Any <UriString>(), Arg.Any <UriString>(), baseSha, headSha, baseRef, headRef).ReturnsForAnyArgs(Task.FromResult(mergeBaseSha));
gitClient.ExtractFile(Arg.Any <IRepository>(), mergeBaseSha, fileName).Returns(GetFileTask(mergeBaseFileContent));
gitClient.ExtractFile(Arg.Any <IRepository>(), baseSha, fileName).Returns(GetFileTask(baseFileContent));
gitClient.ExtractFile(Arg.Any <IRepository>(), headSha, fileName).Returns(GetFileTask(headFileContent));
return(await service.ExtractDiffFiles(repositoryModel, pullRequest, fileName, checkedOut));
}