I am using jest and istanbul in my ReactJS project to write test cases and check on the test coverage.
How do I ensure using a pre-commit hook that test coverage for any file, that I have staged to git, doesn't decrease from its current value before its committed?
You should check coverageThreshold documentation of jest from here
Below options are possible for global coverage threshold and file name pattern thresholds.
{
...
"jest": {
"coverageThreshold": {
"global": {
"branches": 50,
"functions": 50,
"lines": 50,
"statements": 50
},
"./src/components/": {
"branches": 40,
"statements": 40
},
"./src/reducers/**/*.js": {
"statements": 90
},
"./src/api/very-important-module.js": {
"branches": 100,
"functions": 100,
"lines": 100,
"statements": 100
}
}
}
}
You can combine this with lint staged and husky to make the check in pre-commit.
In the end, your package.json would look like this:
{
...package.json
"husky": {
"hooks": {
"pre-commit": "jest",
}
}
}