How to solve Jest error with Vue

With vue-cli RC9 it was not straight forward to test a ES6 file. I found some advices but none worked for me. Here is the error I had:

Jest encountered an unexpected token
// ...
SyntaxError: Unexpected token {
// ...

This was happening on line 1 of the first test file… So it seems the ES6 import was not understood and the my code was not being transpiled by babel

The file jest.config.js was missing an instruction to to transform js files as well. So I added it:

transform: {
    “^.+\\.(js|jsx)?$”: “babel-jest”,

But still no luck, same error, I cleaned the cache, reinstalled all the node_modules, nothing was working :(

Finally the problem is that jest was unable to find the module babel-jest … I just had to do:

transform: {
    “^.+\\.(js|jsx)?$”: “<rootDir>/node_modules/babel-jest”,

and it all started to work.

I hope this helps someone.