A directory is missing from your repository
Rails expects certain directories to be present in your app, including
tmp/ and occasionally others.
If they are not in your repository, your tests will fail (though they ran fine locally because you created the directory a long time ago).
To fix this, simply add the directory to your repository.
Git doesn’t allow you to add directories to it, but the standard idiom is instead to add a file called
.gitkeep within the directory. So this should solve your problem:
$ touch log/.gitkeep $ git add log/.gitkeep $ git commit
If this solution is unacceptable (perhaps you symlink your log directory in production), you can also add a post-checkout command to create the directory:
checkout: post: - mkdir -p log