If my twitter feed is anything to go by, lately I’ve been spending some time looking at CSS regression testing using BackstopJS - more on that to come. Invariably though it led to some minor hiccups that really messed up my git-chi. For those who haven’t used BackstopJS in it’s current, rather nascent state, it can be a bit messy to get started for a relative noob like myself. Upon installation, its files sit in a bower_components/backstopjs directory, which is a-ok.

However, annoyances quickly followed as I tried to selectively ignore or track subdirectories and files of the new backstopjs directory. The project comes with it’s very own .gitignore file, which is all very well, unless of course you want to place everything into the one gitignore file at the root directory of your project. The solution I’ve come across is not particularly clean, but is well documented. For instance if you have a directory structure,

├── index.html
└── js
    ├── main.js
    ├── experiment.js
    └── lib
        └── ext.js

where we may very well want to track main.js, but ignore everything else. The documentation above makes it clear that we can’t just get away with adding an exception for main.js,

It is not possible to re-include a file if a parent directory of that file is excluded. Git doesn’t list excluded directories for performance reasons, so any patterns on contained files have no effect, no matter where they are defined.

In other words, we need to specify the parent directory of every file we wish to track. Following this logic our .gitignore should look something like this,


An unfortunate consequence of this is that we would have to specific every parent directory for a given file if we wanted particularly fine-grained control over tracked files.

In the process I also learnt a neat trick with the git status command. If I wish to see all my untracked files, not just directories as per default, I need to add -u option. This will print out all the individual untracked files, which is particularly useful when specifying specific files as above.

All the best and happy New Year!


Tom Martin

Data scientist, London, UK