Get code coverage from Cypress with babel, nyc and istanbul plugin? - reactjs

Question

For a React/Redux project I use Cypress to test the UI. I need to get code coverage from thoses tests to have the details in Sonar (but that's another story).
So I began reading the docs from Cypress: https://docs.cypress.io/guides/tooling/code-coverage.html
I followed the instructions and found the differents plugins but nothing work. After running Cypress tests I have no coverage results and when I try to run the server with instrumented code on transpilation and try to get window.__coverage__ it's undefined.
So here is my configuration.
My devDep and NYC conf in package.json:
"devDependencies": {
"#cypress/code-coverage": "^1.8.0",
"babel-cli": "^6.26.0",
"babel-plugin-istanbul": "^5.2.0",
"babel-plugin-react-intl": "^2.4.0",
"babel-plugin-transform-class-properties": "^6.24.1",
"babel-preset-react-app": "^3.1.2",
"cross-env": "^5.2.0",
"cypress": "3.1.0",
"istanbul-lib-coverage": "^2.0.5",
"jest-junit-reporter": "^1.1.0",
"junit": "^1.4.9",
"nyc": "^14.1.1",
"react-test-renderer": "^16.3.0"
[...]
},
"scripts": {
"start": "react-scripts start",
[...]
"test:unit:local": "react-scripts test --env=jsdom .*_test.js",
"test:unit": "npm run test:unit:local -- --ci --coverage --testResultsProcessor ./node_modules/jest-junit-reporter",
"test:integ:local": "cypress run --reporter junit",
"test:integ": "start-server-and-test start http://localhost:3000 test:integ:local",
"test": "cross-env NODE_ENV=test && npm run test:unit && npm run test:integ"
},
"nyc": {
"sourceMap": false,
"instrument": false
}
My .babelrc file:
{
"presets": ["#babel/preset-react"],
"plugins": [
[ "react-intl", {
"messagesDir": "./src/messages",
"extractSourceLocation": true
}],
"transform-class-properties",
"istanbul"
],
"env": {
"test": {
"plugins": [ "transform-class-properties", "istanbul" ]
}
}
}
My \cypress\support\index.js contains this line :
import '#cypress/code-coverage/support'
And here is my \cypress\plugins\index.js:
module.exports = (on, config) => {
on('task', require('#cypress/code-coverage/task'))
on('file:preprocessor', require('#cypress/code-coverage/use-babelrc'))
return config
}
So I expect to have a result like you can see on the Cypress docs.
The website is generated but the files containing coverage reports are empty.
And I don't understand what's wrong in my configuration.

Answer 1

Try the following line:
"start": "react-scripts -r #cypress/instrument-cra start",

Answer 2

I faced this issue too. Wasn't able to get code coverage. Downgrading nyc version from 14.x.x to 13.x.x fixed the problem, as mentioned here.