Ryan Lanciaux

Random programming blog.

Test React Components Using Jest (on Windows)

I’m currently going through the process creating unit tests for Griddle and thought it would be good to document the steps I took to get Jest up and running. I did not find it as simple as typing npm install -g jest-cli, however it was not too bad.

My primary machine is running Windows 8 – these steps may be a bit different if you’re on Mac / Linux.

  1. Install Python - Install version 2.7 of Python and add it to your path or create a PYTHONPATH environment variable.
  2. Install Visual Studio (Express Edition is Fine) - Thankfully, this step was not required for me as I already use Visual Studio. We will need this for some of modules that are compiled when we are installing Jest. (Express editions available here – get one of the versions that has C++)
  3. Set Visual Studio Version Flags - this step tripped me up a bit at first. We need to tell node-gyp (something that is used for compiling addons) what version of Visual Studio we want to compile with. You can do this either through an environment variable GYP_MSVS_VERSION or the command line option --msvs_version. My environment variable looks a bit like this GYP_MSVS_VERSION=2013 but if you are using Express, I think you have to say GYP_MSVS_VERSION=2013e
  4. Install Jest-CLI - Now you can run the command on the Jest docs site npm install jest-cli --save-dev

At this point you should be ready to run Jest, however, I experienced some further trouble on Windows against React components. In the react example, the package.json contains "unmockedModulePathPatterns": ["<rootDir>/node_modules/react"] which is basically stating that we don’t want to mock React when running our tests. Unfortunately, it seemed like we need to change this path to just "unmockedModulePathPatterns": ["react"] in order for the test to run successfully (again on Windows – seems fine on other OS). See this GitHub issue for more on that.

For more reading on installing Jest’s requirements see: