test: bring back code coverage (#12)

README.md

@@ -74,6 +74,10 @@ if (/KAIOS/.test(navigator.userAgent)) {
 
     npm test
 
+### Code coverage
+
+    npm run cover
+
 ### Manual KaiOS app test
 
 The `index.html` and `manifest.webapp` files are designed for a quick-and-dirty KaiOS app test.

karma.conf.js

@@ -2,13 +2,15 @@ const resolve = require('@rollup/plugin-node-resolve').default
 const cjs = require('@rollup/plugin-commonjs')
 const json = require('@rollup/plugin-json')
 const polyfills = require('rollup-plugin-node-polyfills')
+const istanbul = require('rollup-plugin-istanbul')
 
 module.exports = function (config) {
   config.set({
     plugins: [
       require('karma-rollup-preprocessor'),
       require('karma-mocha'),
-      require('karma-chrome-launcher')
+      require('karma-chrome-launcher'),
+      ...(process.env.COVERAGE ? [require('karma-coverage')] : [])
     ],
 
     files: [
@@ -27,7 +29,15 @@ module.exports = function (config) {
         }),
         cjs(),
         json(),
-        polyfills()
+        polyfills(),
+        ...(process.env.COVERAGE ? [
+          istanbul ({
+            exclude: [
+              'test/*.js',
+              'node_modules/**/*.js'
+            ]
+          })
+        ] : [])
       ],
       output: {
         format: 'iife', // Helps prevent naming collisions.
@@ -40,6 +50,9 @@ module.exports = function (config) {
 
     browsers: [
       'ChromeHeadless'
-    ]
+    ],
+    ...(process.env.COVERAGE ? {
+      reporters: ['coverage']
+    } : null)
   })
 }