JarCasting
Istanbul Instrumenter Loader
Instrument JS files with istanbul-lib-instrument for subsequent code coverage reporting
Install
npm i -D istanbul-instrumenter-loader
Usage
References
Structure
├─ src
│ |– components
│ | |– bar
│ | │ |─ index.js
│ | |– foo/
│ |– index.js
|– test
| |– src
| | |– components
| | | |– foo
| | | | |– index.js
To create a code coverage report for all components (even for those for which you have no tests yet) you have to require all the 1) sources and 2) tests. Something like it's described in "alternative usage" of karma-webpack
test/index.js
// requires all tests in `project/test/src/components/**/index.js`
const tests = require.context('./src/components/', true, /index\.js$/);
tests.keys().forEach(tests);
// requires all components in `project/src/components/**/index.js`
const components = require.context('../src/components/', true, /index\.js$/);
components.keys().forEach(components);
ℹ️ This file will be the onlyentrypoint forkarma
karma.conf.js
config.set({
...
files: [
'test/index.js'
],
preprocessors: {
'test/index.js': 'webpack'
},
webpack: {
...
module: {
rules: [
// instrument only testing sources with Istanbul
{
test: /\.js$/,
use: { loader: 'istanbul-instrumenter-loader' },
include: path.resolve('src/components/')
}
]
}
...
},
reporters: [ 'progress', 'coverage-istanbul' ],
coverageIstanbulReporter: {
reports: [ 'text-summary' ],
fixWebpackSourcePaths: true
}
...
});
with Babel
You must run the instrumentation as a post step
webpack.config.js
{
test: /\.js$|\.jsx$/,
use: {
loader: 'istanbul-instrumenter-loader',
options: { esModules: true }
},
enforce: 'post',
exclude: /node_modules|\.spec\.js$/,
}
Options
The loader supports all options supported by istanbul-lib-instrument
| Name | Type | Default | Description |
|---|---|---|---|
debug |
{Boolean} |
false |
Turn on debugging mode |
compact |
{Boolean} |
true |
Generate compact code |
autoWrap |
{Boolean} |
false |
Set to true to allow return statements outside of functions |
esModules |
{Boolean} |
false |
Set to true to instrument ES2015 Modules |
coverageVariable |
{String} |
__coverage__ |
Name of global coverage variable |
preserveComments |
{Boolean} |
false |
Preserve comments in output |
produceSourceMap |
{Boolean} |
false |
Set to true to produce a source map for the instrumented code |
sourceMapUrlCallback |
{Function} |
null |
A callback function that is called when a source map URL is found in the original code. This function is called with the source filename and the source map URL |
webpack.config.js
{
test: /\.js$/,
use: {
loader: 'istanbul-instrumenter-loader',
options: {...options}
}
}
Maintainers
 Kir Belevich |
 Juho Vepsäläinen |
 Joshua Wiens |
 Michael Ciniawsky |
 Matt Lewis |
