fix(index): merge input and instrumented sourcemaps

.travis.yml

@@ -14,10 +14,6 @@ jobs:
       node_js: 6
       env: WEBPACK_VERSION=latest JOB_PART=test
       script: npm run travis:$JOB_PART
-    - <<: *test-latest
-      node_js: 4.8
-      env: WEBPACK_VERSION=latest JOB_PART=test
-      script: npm run travis:$JOB_PART
     - <<: *test-latest
       node_js: 8
       env: WEBPACK_VERSION=latest JOB_PART=lint

appveyor.yml

@@ -11,9 +11,6 @@ environment:
     - nodejs_version: '6'
       webpack_version: latest
       job_part: test
-    - nodejs_version: '4.8'
-      webpack_version: latest
-      job_part: test
 build: 'off'
 matrix:
   fast_finish: true

package.json

@@ -9,8 +9,9 @@
   ],
   "dependencies": {
     "convert-source-map": "^1.5.0",
-    "istanbul-lib-instrument": "^1.7.3",
+    "istanbul-lib-instrument": "^2.3.2",
     "loader-utils": "^1.1.0",
+    "merge-source-map": "^1.1.0",
     "schema-utils": "^0.3.0"
   },
   "engines": {
@@ -55,7 +56,7 @@
     "nsp": "^2.8.1",
     "pre-commit": "^1.2.2",
     "standard-version": "^4.2.0",
-    "webpack": "^3.8.1",
+    "webpack": "^4.20.2",
     "webpack-defaults": "^1.6.0"
   },
   "homepage": "https://github.com/webpack-contrib/istanbul-instrumenter-loader",

src/index.js

@@ -2,6 +2,7 @@ import { createInstrumenter } from 'istanbul-lib-instrument';
 import loaderUtils from 'loader-utils';
 import validateOptions from 'schema-utils';
 import convert from 'convert-source-map';
+import merge from 'merge-source-map';
 /* eslint-disable-line */
 const schema = require('./options');
 
@@ -21,7 +22,19 @@ export default function (source, sourceMap) {
 
   const instrumenter = createInstrumenter(options);
 
-  instrumenter.instrument(source, this.resourcePath, (error, instrumentedSource) => {
-    this.callback(error, instrumentedSource, instrumenter.lastSourceMap());
-  }, srcMap);
+  instrumenter.instrument(
+    source,
+    // This name must be unique for source map merging to work with multiple merges regardless of
+    // file names.
+    `${this.resourcePath}.pre-istanbul.js`,
+    (error, instrumentedSource) => {
+      let instrumentedSourceMap = instrumenter.lastSourceMap();
+      if (srcMap && instrumentedSourceMap) {
+        // merge srcMap and instrumentedSourceMap together
+        instrumentedSourceMap = merge(srcMap, instrumentedSourceMap);
+      }
+      this.callback(error, instrumentedSource, instrumentedSourceMap);
+    },
+    srcMap,
+  );
 }

test/index.test.js

@@ -1,7 +1,11 @@
+import path from 'path';
+import fs from 'fs';
 import webpack from './utils/webpack';
 
+const fixture = 'basic.js';
+
 test('instrument code', async () => {
-  const stats = await webpack();
+  const stats = await webpack({ fixture });
   const instrumentedSource = stats.compilation.assets['main.js'].source();
   expect(instrumentedSource).toMatchSnapshot();
 });
@@ -11,8 +15,12 @@ test('sourcemap files on by default', async () => {
     extend: {
       devtool: 'source-map',
     },
+    fixture,
   });
   const sourceMap = stats.compilation.assets['main.js.map'].source();
+  const originalSource = fs.readFileSync(path.join(__dirname, 'fixtures', fixture), 'utf8');
+  const [sourceMapSource] = JSON.parse(sourceMap).sourcesContent;
+  expect(sourceMapSource).toEqual(originalSource);
   expect(sourceMap).toMatchSnapshot();
   expect(stats.compilation.errors).toMatchSnapshot('errors');
   expect(stats.compilation.warnings).toMatchSnapshot('warnings');
@@ -26,8 +34,14 @@ test('disabled sourcemaps', async () => {
     options: {
       produceSourceMap: false,
     },
+    fixture,
   });
   const sourceMap = stats.compilation.assets['main.js.map'].source();
+  const instrumentedSource = stats.compilation.assets['main.js'].source();
+  const [originalSource] = JSON.parse(sourceMap).sourcesContent;
+  // Webpack adds newline after "use strict" that we need to remove to compare.
+  const trimmedSourceWithoutFooter = originalSource.slice(16, originalSource.length);
+  expect(instrumentedSource).toContain(trimmedSourceWithoutFooter);
   expect(sourceMap).toMatchSnapshot();
   expect(stats.compilation.errors).toMatchSnapshot('errors');
   expect(stats.compilation.warnings).toMatchSnapshot('warnings');

test/utils/webpack.js

@@ -6,6 +6,7 @@ const loader = require.resolve('./loader');
 
 export default function ({ fixture = 'basic.js', options, extend = {} } = {}) {
   const config = {
+    mode: 'development',
     entry: path.join(__dirname, '..', 'fixtures', fixture),
     output: {
       path: path.join(__dirname, '..', 'fixtures', 'dist'),
@@ -22,11 +23,9 @@ export default function ({ fixture = 'basic.js', options, extend = {} } = {}) {
       }],
     },
     ...extend,
-    plugins: [
-      new webpack.optimize.CommonsChunkPlugin({
-        name: 'manifest',
-      }),
-    ],
+    optimization: {
+      runtimeChunk: 'single',
+    },
   };
 
   return new Promise((resolve, reject) => {