Reputation: 10992
I am using Mocha for testing my NodeJS application. I am not able to figure out how to use its code coverage feature. I tried googling it but did not find any proper tutorial. Please help.
Upvotes: 382
Views: 208729
Reputation: 16294
Now (2024) the preferred way to use istanbul is via its "state of the art command line interface" nyc.
First, install it in your project with
npm i nyc --save-dev
Then, if you have a npm based project, just change the test script inside the scripts
object of your package.json file to execute code coverage of your mocha tests:
{
"scripts": {
"test": "nyc --reporter=text mocha"
}
}
Now run your tests
npm test
and you will see a table like this in your console, just after your tests output:
Just use
nyc --reporter=html
instead of text
. Now it will produce a report inside ./coverage/index.html
.
Istanbul supports a wide range of report formats. Just look at its reports library to find the most useful for you.
Just add a --reporter=REPORTER_NAME
option for each format you want.
For example, with
nyc --reporter=html --reporter=text
you will have both the console and the html report.
Just add another script in your package.json
and leave the test
script with only your test runner (e.g. mocha):
{
"scripts": {
"test": "mocha",
"test-with-coverage": "nyc --reporter=text mocha"
}
}
Now run this custom script
npm run test-with-coverage
to run tests with code coverage.
Fail if the total code coverage is below 90%:
nyc --check-coverage --lines 90
Fail if the code coverage of at least one file is below 90%:
nyc --check-coverage --lines 90 --per-file
Upvotes: 253
Reputation: 709
The accepted answer (nyc) does not work if you are using ESM modules.
C8 appears to be the best solution now, which leverages built-in NodeJS capabilities and utilizes istanbul (like nyc, and shares the same config files).
npm install -g c8
c8 mocha
It will use .nycrc for configuration. A sample configuration I'm using is:
{
"all": true,
"exclude": ["test"],
"output": "reports",
"reporter" : [
"html",
"text"
]
}
(Note: I was pointed to c8 by an answer to another question https://stackoverflow.com/a/69846825/1949430)
Upvotes: 25
Reputation: 34327
You need an additional library for code coverage, and you are going to be blown away by how powerful and easy istanbul is. Try the following, after you get your mocha tests to pass:
npm install nyc
Now, simply place the command nyc in front of your existing test command, for example:
{
"scripts": {
"test": "nyc mocha"
}
}
Upvotes: 517
Reputation: 2824
Blanket.js works perfect too.
npm install --save-dev blanket
in front of your test/tests.js
require('blanket')({
pattern: function (filename) {
return !/node_modules/.test(filename);
}
});
run mocha -R html-cov > coverage.html
Upvotes: 20