How to ignore lines for code coverage in Jest - code-coverage

Question

In Jest, is there any way to ignore code for test coverage?
I tried using
/* istanbul ignore next */
But it doesn't seem to work.

Answer 1

It works.
(function(global) {
var defineAsGlobal = true;
/* istanbul ignore next */
if(typeof exports === 'object') {
module.exports = lib;
defineAsGlobal = false;
}
/* istanbul ignore next */
if(typeof modules === 'object' && typeof modules.define === 'function') {
modules.define('lib', function(provide) {
provide(lib);
});
defineAsGlobal = false;
}
/* istanbul ignore next */
if(typeof define === 'function') {
define(function(require, exports, module) {
module.exports = lib;
});
defineAsGlobal = false;
}
/* istanbul ignore next */
defineAsGlobal && (global.lib = lib);
})(this);
Sample project https://github.com/ilyar/sandbox/tree/master/jest

Answer 2

Update for anyone that finds this at a later date.
/* istanbul ignore next */
Will work but as read from The Jest Official Documentation:
coveragePathIgnorePatterns seems to not have any effect.
Make sure you are not using the babel-plugin-istanbul plugin. Jest
wraps Istanbul, and therefore also tells Istanbul what files to
instrument with coverage collection. When using babel-plugin-istanbul,
every file that is processed by Babel will have coverage collection
code, hence it is not being ignored by coveragePathIgnorePatterns.
The documentation can be found here: Documentation
So in order to fix this issue uninstall babel-plugin-istanbul:
If it is a library based only on javascript, than you can just run npm uninstall --save babel-plugin-istanbul or npm uninstall --save-dev babel-plugin-istanbul
If you've installed a library with native content that requires linking, and you've linked it with rnpm then you can do: rnpm unlink package_name then follow step 1 - Aakash Sigdel
This quote was from Aakash Sigdel found here: quote

Answer 3

Found a workaround (spaces before and after the comment seem to be necessary):
class Foo {
bar /* istanbul ignore next */ () {
return 'biu~';
}
}

Answer 4

Just for anyone finding this who uses the v8 provider:
the docs now state how to ignore lines with different providers, and link to more details. But basically either /* c8 ignore next */ or /* c8 ignore start */ + /*c8 ignore end */ should work well with the v8 provider.
Example:
/* c8 ignore next */
if (process.env.DEBUG) console.log('debug');
/* c8 ignore start */
switch (process.env.DEBUG) {
case '1':
console.log('some verbosity');
break;
case '2':
console.log('a lot of verbosity');
break;
}
/* c8 ignore end */

Answer 5

In my case, I had coverageProvider: 'v8', and it was causing this to break. doing: coverageProvider: 'babel', fixed it and the pragma works great.

Answer 6

According to a babel issue thread Istambul appears to have a bug where it assumes the preceding line of code is terminated with a semi-colon...
constructor(message: string) {
// TODO: how do I get Jest code coverage for "super(message)?
// /* istanbul ignore next */ assumes the preceding line of code is terminated with a ;
DEBUG: console.log();
/* istanbul ignore next */
super(message);
}