From 68872838e4aefd4c0d851cd78451842defb4ffe3 Mon Sep 17 00:00:00 2001
From: David Manthey <david.manthey@kitware.com>
Date: Fri, 24 Aug 2018 11:45:30 -0400
Subject: [PATCH] Fix reporting coverage when using babel.

If the istanbul-instrumenter-loader is added in a separate rule from the
babel-loader, the line numbers reported by coverage are wrong.
---
 karma-base.js          |  2 +-
 karma-cov.conf.js      | 12 +++++-------
 webpack.base.config.js | 28 ++++++++++++++++++++++++----
 3 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/karma-base.js b/karma-base.js
index bd83e07e64..366771fc1c 100644
--- a/karma-base.js
+++ b/karma-base.js
@@ -1,4 +1,4 @@
-var webpack_config = require('./webpack.config');
+var webpack_config = require('./webpack.base.config');
 var url = require('url');
 var fs = require('fs');
 var path = require('path');
diff --git a/karma-cov.conf.js b/karma-cov.conf.js
index 4067c16e22..272cc840c6 100644
--- a/karma-cov.conf.js
+++ b/karma-cov.conf.js
@@ -1,8 +1,6 @@
 // Defines a test server for running jasmine unit tests
 // with coverage support.
 
-var path = require('path');
-
 /**
  * Return URL friendly browser string
  */
@@ -40,11 +38,11 @@ module.exports = function (config) {
       {type: 'text'}
     ]
   };
-  karma_config.webpack.module.rules.unshift({
-    test: /\.js$/,
-    include: path.resolve('src/'),
-    exclude: path.resolve('src/polyfills.js'),
-    use: ['istanbul-instrumenter-loader']
+  /* Alter our first webpack module rule which should just apply to src/*.js
+   * files. */
+  karma_config.webpack.module.rules[0].use.push({
+    loader: 'istanbul-instrumenter-loader',
+    options: {esModules: true}
   });
 
   config.set(karma_config);
diff --git a/webpack.base.config.js b/webpack.base.config.js
index 8afbbb0d69..094059bb46 100644
--- a/webpack.base.config.js
+++ b/webpack.base.config.js
@@ -75,12 +75,32 @@ module.exports = {
   */
   module: {
     rules: [{
+      /* The first rule only includes src/*.js so that it can conveniently be
+       * modified for istanbul instrumentation */
+      test: /\.js$/,
+      include: path.resolve('src'),
+      exclude: path.resolve('src/polyfills.js'),
+      use: [{
+        loader: 'babel-loader',
+        options: {
+          presets: [[
+            'env', {
+              targets: {
+                browsers: ['defaults'],
+                uglify: true
+              },
+              useBuiltIns: 'usage'
+            }
+          ]],
+          cacheDirectory: true
+        }
+      }]
+    }, {
       test: /\.js$/,
       include: [
-        path.resolve(__dirname, 'src'),
-        path.resolve(__dirname, 'tests'),
-        path.resolve(__dirname, 'examples'),
-        path.resolve(__dirname, 'tutorials')
+        path.resolve('tests'),
+        path.resolve('examples'),
+        path.resolve('tutorials')
       ],
       use: [{
         loader: 'babel-loader',