feat: generate higher quality SourceMaps (#408)

evilebottnawi · web-flow · commit b1df135b2a2e · 2019-07-31T15:19:04.000+03:00
diff --git a/src/index.js b/src/index.js
@@ -299,7 +299,8 @@ class UglifyJsPlugin {
               file,
               JSON.parse(map),
               input,
-              inputSourceMap
+              inputSourceMap,
+              true
             );
           } else {
             outputSource = new RawSource(code);
diff --git a/src/minify.js b/src/minify.js
@@ -152,11 +152,9 @@ const minify = (options) => {
   // Copy uglify options
   const uglifyOptions = buildUglifyOptions(options.uglifyOptions);
 
-  // Add source map data
+  // Let uglify-js generate a SourceMap
   if (inputSourceMap) {
-    uglifyOptions.sourceMap = {
-      content: inputSourceMap,
-    };
+    uglifyOptions.sourceMap = true;
   }
 
   const extractedComments = [];
diff --git a/test/__snapshots__/sourceMap-option.test.js.snap b/test/__snapshots__/sourceMap-option.test.js.snap
@@ -18,21 +18,73 @@ exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`
 
 exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`false\`): warnings 1`] = `Array []`;
 
-exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: broken-source-map.js 1`] = `"var test = 1;"`;
+exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: broken-source-map.js 1`] = `"var test=1;"`;
 
-exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: errors 1`] = `
-Array [
-  "Error: broken-source-map.js from UglifyJs
-Error: \\"version\\" is a required argument.",
-]
-`;
+exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: errors 1`] = `Array []`;
 
 exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: main.fa5a416a70ded1ab6043.js 1`] = `
 "!function(n){var r={};function o(e){if(r[e])return r[e].exports;var t=r[e]={i:e,l:!1,exports:{}};return n[e].call(t.exports,t,t.exports,o),t.l=!0,t.exports}o.m=n,o.c=r,o.d=function(e,t,n){o.o(e,t)||Object.defineProperty(e,t,{enumerable:!0,get:n})},o.r=function(e){\\"undefined\\"!=typeof Symbol&&Symbol.toStringTag&&Object.defineProperty(e,Symbol.toStringTag,{value:\\"Module\\"}),Object.defineProperty(e,\\"__esModule\\",{value:!0})},o.t=function(t,e){if(1&e&&(t=o(t)),8&e)return t;if(4&e&&\\"object\\"==typeof t&&t&&t.__esModule)return t;var n=Object.create(null);if(o.r(n),Object.defineProperty(n,\\"default\\",{enumerable:!0,value:t}),2&e&&\\"string\\"!=typeof t)for(var r in t)o.d(n,r,function(e){return t[e]}.bind(null,r));return n},o.n=function(e){var t=e&&e.__esModule?function(){return e.default}:function(){return e};return o.d(t,\\"a\\",t),t},o.o=function(e,t){return Object.prototype.hasOwnProperty.call(e,t)},o.p=\\"\\",o(o.s=0)}([function(e,t){e.exports=function(){console.log(7)}}]);
 //# sourceMappingURL=main.fa5a416a70ded1ab6043.js.map"
 `;
 
-exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: main.fa5a416a70ded1ab6043.js.map 1`] = `"{\\"version\\":3,\\"sources\\":[\\"webpack:///webpack/bootstrap\\",\\"webpack:///./test/fixtures/entry.js\\"],\\"names\\":[\\"installedModules\\",\\"__webpack_require__\\",\\"moduleId\\",\\"exports\\",\\"module\\",\\"i\\",\\"l\\",\\"modules\\",\\"call\\",\\"m\\",\\"c\\",\\"d\\",\\"name\\",\\"getter\\",\\"o\\",\\"Object\\",\\"defineProperty\\",\\"enumerable\\",\\"get\\",\\"r\\",\\"Symbol\\",\\"toStringTag\\",\\"value\\",\\"t\\",\\"mode\\",\\"__esModule\\",\\"ns\\",\\"create\\",\\"key\\",\\"bind\\",\\"n\\",\\"object\\",\\"property\\",\\"prototype\\",\\"hasOwnProperty\\",\\"p\\",\\"s\\",\\"console\\",\\"log\\",\\"b\\"],\\"mappings\\":\\"aACA,IAAAA,EAAA,GAGA,SAAAC,EAAAC,GAGA,GAAAF,EAAAE,GACA,OAAAF,EAAAE,GAAAC,QAGA,IAAAC,EAAAJ,EAAAE,GAAA,CACAG,EAAAH,EACAI,GAAA,EACAH,QAAA,IAUA,OANAI,EAAAL,GAAAM,KAAAJ,EAAAD,QAAAC,IAAAD,QAAAF,GAGAG,EAAAE,GAAA,EAGAF,EAAAD,QAKAF,EAAAQ,EAAAF,EAGAN,EAAAS,EAAAV,EAGAC,EAAAU,EAAA,SAAAR,EAAAS,EAAAC,GACAZ,EAAAa,EAAAX,EAAAS,IACAG,OAAAC,eAAAb,EAAAS,EAAA,CAA0CK,YAAA,EAAAC,IAAAL,KAK1CZ,EAAAkB,EAAA,SAAAhB,GACA,oBAAAiB,eAAAC,aACAN,OAAAC,eAAAb,EAAAiB,OAAAC,YAAA,CAAwDC,MAAA,WAExDP,OAAAC,eAAAb,EAAA,cAAiDmB,OAAA,KAQjDrB,EAAAsB,EAAA,SAAAD,EAAAE,GAEA,GADA,EAAAA,IAAAF,EAAArB,EAAAqB,IACA,EAAAE,EAAA,OAAAF,EACA,KAAAE,GAAA,iBAAAF,QAAAG,WAAA,OAAAH,EACA,IAAAI,EAAAX,OAAAY,OAAA,MAGA,GAFA1B,EAAAkB,EAAAO,GACAX,OAAAC,eAAAU,EAAA,WAAyCT,YAAA,EAAAK,UACzC,EAAAE,GAAA,iBAAAF,EAAA,QAAAM,KAAAN,EAAArB,EAAAU,EAAAe,EAAAE,EAAA,SAAAA,GAAgH,OAAAN,EAAAM,IAAqBC,KAAA,KAAAD,IACrI,OAAAF,GAIAzB,EAAA6B,EAAA,SAAA1B,GACA,IAAAS,EAAAT,KAAAqB,WACA,WAA2B,OAAArB,EAAA,SAC3B,WAAiC,OAAAA,GAEjC,OADAH,EAAAU,EAAAE,EAAA,IAAAA,GACAA,GAIAZ,EAAAa,EAAA,SAAAiB,EAAAC,GAAsD,OAAAjB,OAAAkB,UAAAC,eAAA1B,KAAAuB,EAAAC,IAGtD/B,EAAAkC,EAAA,GAIAlC,IAAAmC,EAAA,mBC7EAhC,EAAAD,QAAA,WAEAkC,QAAAC,IAAAC\\",\\"file\\":\\"main.fa5a416a70ded1ab6043.js\\",\\"sourceRoot\\":\\"\\"}"`;
+exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: main.fa5a416a70ded1ab6043.js.map 1`] = `
+{
+  "version": 3,
+  "sources": [
+    "webpack:///webpack/bootstrap",
+    "webpack:///./test/fixtures/entry.js"
+  ],
+  "names": [
+    "installedModules",
+    "__webpack_require__",
+    "moduleId",
+    "exports",
+    "module",
+    "i",
+    "l",
+    "modules",
+    "call",
+    "m",
+    "c",
+    "d",
+    "name",
+    "getter",
+    "o",
+    "Object",
+    "defineProperty",
+    "enumerable",
+    "get",
+    "r",
+    "Symbol",
+    "toStringTag",
+    "value",
+    "t",
+    "mode",
+    "__esModule",
+    "ns",
+    "create",
+    "key",
+    "bind",
+    "n",
+    "object",
+    "property",
+    "prototype",
+    "hasOwnProperty",
+    "p",
+    "s",
+    "console",
+    "log",
+    "b"
+  ],
+  "mappings": "aACE,IAAIA,EAAmB,GAGvB,SAASC,EAAoBC,GAG5B,GAAGF,EAAiBE,GACnB,OAAOF,EAAiBE,GAAUC,QAGnC,IAAIC,EAASJ,EAAiBE,GAAY,CACzCG,EAAGH,EACHI,GAAG,EACHH,QAAS,IAUV,OANAI,EAAQL,GAAUM,KAAKJ,EAAOD,QAASC,EAAQA,EAAOD,QAASF,GAG/DG,EAAOE,GAAI,EAGJF,EAAOD,QAKfF,EAAoBQ,EAAIF,EAGxBN,EAAoBS,EAAIV,EAGxBC,EAAoBU,EAAI,SAASR,EAASS,EAAMC,GAC3CZ,EAAoBa,EAAEX,EAASS,IAClCG,OAAOC,eAAeb,EAASS,EAAM,CAAEK,YAAY,EAAMC,IAAKL,KAKhEZ,EAAoBkB,EAAI,SAAShB,GACX,oBAAXiB,QAA0BA,OAAOC,aAC1CN,OAAOC,eAAeb,EAASiB,OAAOC,YAAa,CAAEC,MAAO,WAE7DP,OAAOC,eAAeb,EAAS,aAAc,CAAEmB,OAAO,KAQvDrB,EAAoBsB,EAAI,SAASD,EAAOE,GAEvC,GADU,EAAPA,IAAUF,EAAQrB,EAAoBqB,IAC/B,EAAPE,EAAU,OAAOF,EACpB,GAAW,EAAPE,GAA8B,iBAAVF,GAAsBA,GAASA,EAAMG,WAAY,OAAOH,EAChF,IAAII,EAAKX,OAAOY,OAAO,MAGvB,GAFA1B,EAAoBkB,EAAEO,GACtBX,OAAOC,eAAeU,EAAI,UAAW,CAAET,YAAY,EAAMK,MAAOA,IACtD,EAAPE,GAA4B,iBAATF,EAAmB,IAAI,IAAIM,KAAON,EAAOrB,EAAoBU,EAAEe,EAAIE,EAAK,SAASA,GAAO,OAAON,EAAMM,IAAQC,KAAK,KAAMD,IAC9I,OAAOF,GAIRzB,EAAoB6B,EAAI,SAAS1B,GAChC,IAAIS,EAAST,GAAUA,EAAOqB,WAC7B,WAAwB,OAAOrB,EAAgB,SAC/C,WAA8B,OAAOA,GAEtC,OADAH,EAAoBU,EAAEE,EAAQ,IAAKA,GAC5BA,GAIRZ,EAAoBa,EAAI,SAASiB,EAAQC,GAAY,OAAOjB,OAAOkB,UAAUC,eAAe1B,KAAKuB,EAAQC,IAGzG/B,EAAoBkC,EAAI,GAIjBlC,EAAoBA,EAAoBmC,EAAI,G,gBC7ErDhC,EAAOD,QAAU,WAEfkC,QAAQC,IAAIC",
+  "file": "main.fa5a416a70ded1ab6043.js",
+  "sourcesContent": [
+    " \\t// The module cache\\n \\tvar installedModules = {};\\n\\n \\t// The require function\\n \\tfunction __webpack_require__(moduleId) {\\n\\n \\t\\t// Check if module is in cache\\n \\t\\tif(installedModules[moduleId]) {\\n \\t\\t\\treturn installedModules[moduleId].exports;\\n \\t\\t}\\n \\t\\t// Create a new module (and put it into the cache)\\n \\t\\tvar module = installedModules[moduleId] = {\\n \\t\\t\\ti: moduleId,\\n \\t\\t\\tl: false,\\n \\t\\t\\texports: {}\\n \\t\\t};\\n\\n \\t\\t// Execute the module function\\n \\t\\tmodules[moduleId].call(module.exports, module, module.exports, __webpack_require__);\\n\\n \\t\\t// Flag the module as loaded\\n \\t\\tmodule.l = true;\\n\\n \\t\\t// Return the exports of the module\\n \\t\\treturn module.exports;\\n \\t}\\n\\n\\n \\t// expose the modules object (__webpack_modules__)\\n \\t__webpack_require__.m = modules;\\n\\n \\t// expose the module cache\\n \\t__webpack_require__.c = installedModules;\\n\\n \\t// define getter function for harmony exports\\n \\t__webpack_require__.d = function(exports, name, getter) {\\n \\t\\tif(!__webpack_require__.o(exports, name)) {\\n \\t\\t\\tObject.defineProperty(exports, name, { enumerable: true, get: getter });\\n \\t\\t}\\n \\t};\\n\\n \\t// define __esModule on exports\\n \\t__webpack_require__.r = function(exports) {\\n \\t\\tif(typeof Symbol !== 'undefined' && Symbol.toStringTag) {\\n \\t\\t\\tObject.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });\\n \\t\\t}\\n \\t\\tObject.defineProperty(exports, '__esModule', { value: true });\\n \\t};\\n\\n \\t// create a fake namespace object\\n \\t// mode & 1: value is a module id, require it\\n \\t// mode & 2: merge all properties of value into the ns\\n \\t// mode & 4: return value when already ns object\\n \\t// mode & 8|1: behave like require\\n \\t__webpack_require__.t = function(value, mode) {\\n \\t\\tif(mode & 1) value = __webpack_require__(value);\\n \\t\\tif(mode & 8) return value;\\n \\t\\tif((mode & 4) && typeof value === 'object' && value && value.__esModule) return value;\\n \\t\\tvar ns = Object.create(null);\\n \\t\\t__webpack_require__.r(ns);\\n \\t\\tObject.defineProperty(ns, 'default', { enumerable: true, value: value });\\n \\t\\tif(mode & 2 && typeof value != 'string') for(var key in value) __webpack_require__.d(ns, key, function(key) { return value[key]; }.bind(null, key));\\n \\t\\treturn ns;\\n \\t};\\n\\n \\t// getDefaultExport function for compatibility with non-harmony modules\\n \\t__webpack_require__.n = function(module) {\\n \\t\\tvar getter = module && module.__esModule ?\\n \\t\\t\\tfunction getDefault() { return module['default']; } :\\n \\t\\t\\tfunction getModuleExports() { return module; };\\n \\t\\t__webpack_require__.d(getter, 'a', getter);\\n \\t\\treturn getter;\\n \\t};\\n\\n \\t// Object.prototype.hasOwnProperty.call\\n \\t__webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };\\n\\n \\t// __webpack_public_path__\\n \\t__webpack_require__.p = \\"\\";\\n\\n\\n \\t// Load entry module and return exports\\n \\treturn __webpack_require__(__webpack_require__.s = 0);\\n",
+    "// foo\\n/* @preserve*/\\n// bar\\nvar a = 2 + 2;\\n\\nmodule.exports = function Foo() {\\n  var b = 2 + 2;\\n  console.log(b + 1 + 2);\\n};\\n"
+  ],
+  "sourceRoot": ""
+}
+`;
 
 exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`) and source map invalid: warnings 1`] = `
 Array [
@@ -47,6 +99,63 @@ exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`
 //# sourceMappingURL=main.fa5a416a70ded1ab6043.js.map"
 `;
 
-exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`): main.fa5a416a70ded1ab6043.js.map 1`] = `"{\\"version\\":3,\\"sources\\":[\\"webpack:///webpack/bootstrap\\",\\"webpack:///./test/fixtures/entry.js\\"],\\"names\\":[\\"installedModules\\",\\"__webpack_require__\\",\\"moduleId\\",\\"exports\\",\\"module\\",\\"i\\",\\"l\\",\\"modules\\",\\"call\\",\\"m\\",\\"c\\",\\"d\\",\\"name\\",\\"getter\\",\\"o\\",\\"Object\\",\\"defineProperty\\",\\"enumerable\\",\\"get\\",\\"r\\",\\"Symbol\\",\\"toStringTag\\",\\"value\\",\\"t\\",\\"mode\\",\\"__esModule\\",\\"ns\\",\\"create\\",\\"key\\",\\"bind\\",\\"n\\",\\"object\\",\\"property\\",\\"prototype\\",\\"hasOwnProperty\\",\\"p\\",\\"s\\",\\"console\\",\\"log\\",\\"b\\"],\\"mappings\\":\\"aACA,IAAAA,EAAA,GAGA,SAAAC,EAAAC,GAGA,GAAAF,EAAAE,GACA,OAAAF,EAAAE,GAAAC,QAGA,IAAAC,EAAAJ,EAAAE,GAAA,CACAG,EAAAH,EACAI,GAAA,EACAH,QAAA,IAUA,OANAI,EAAAL,GAAAM,KAAAJ,EAAAD,QAAAC,IAAAD,QAAAF,GAGAG,EAAAE,GAAA,EAGAF,EAAAD,QAKAF,EAAAQ,EAAAF,EAGAN,EAAAS,EAAAV,EAGAC,EAAAU,EAAA,SAAAR,EAAAS,EAAAC,GACAZ,EAAAa,EAAAX,EAAAS,IACAG,OAAAC,eAAAb,EAAAS,EAAA,CAA0CK,YAAA,EAAAC,IAAAL,KAK1CZ,EAAAkB,EAAA,SAAAhB,GACA,oBAAAiB,eAAAC,aACAN,OAAAC,eAAAb,EAAAiB,OAAAC,YAAA,CAAwDC,MAAA,WAExDP,OAAAC,eAAAb,EAAA,cAAiDmB,OAAA,KAQjDrB,EAAAsB,EAAA,SAAAD,EAAAE,GAEA,GADA,EAAAA,IAAAF,EAAArB,EAAAqB,IACA,EAAAE,EAAA,OAAAF,EACA,KAAAE,GAAA,iBAAAF,QAAAG,WAAA,OAAAH,EACA,IAAAI,EAAAX,OAAAY,OAAA,MAGA,GAFA1B,EAAAkB,EAAAO,GACAX,OAAAC,eAAAU,EAAA,WAAyCT,YAAA,EAAAK,UACzC,EAAAE,GAAA,iBAAAF,EAAA,QAAAM,KAAAN,EAAArB,EAAAU,EAAAe,EAAAE,EAAA,SAAAA,GAAgH,OAAAN,EAAAM,IAAqBC,KAAA,KAAAD,IACrI,OAAAF,GAIAzB,EAAA6B,EAAA,SAAA1B,GACA,IAAAS,EAAAT,KAAAqB,WACA,WAA2B,OAAArB,EAAA,SAC3B,WAAiC,OAAAA,GAEjC,OADAH,EAAAU,EAAAE,EAAA,IAAAA,GACAA,GAIAZ,EAAAa,EAAA,SAAAiB,EAAAC,GAAsD,OAAAjB,OAAAkB,UAAAC,eAAA1B,KAAAuB,EAAAC,IAGtD/B,EAAAkC,EAAA,GAIAlC,IAAAmC,EAAA,mBC7EAhC,EAAAD,QAAA,WAEAkC,QAAAC,IAAAC\\",\\"file\\":\\"main.fa5a416a70ded1ab6043.js\\",\\"sourceRoot\\":\\"\\"}"`;
+exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`): main.fa5a416a70ded1ab6043.js.map 1`] = `
+{
+  "version": 3,
+  "sources": [
+    "webpack:///webpack/bootstrap",
+    "webpack:///./test/fixtures/entry.js"
+  ],
+  "names": [
+    "installedModules",
+    "__webpack_require__",
+    "moduleId",
+    "exports",
+    "module",
+    "i",
+    "l",
+    "modules",
+    "call",
+    "m",
+    "c",
+    "d",
+    "name",
+    "getter",
+    "o",
+    "Object",
+    "defineProperty",
+    "enumerable",
+    "get",
+    "r",
+    "Symbol",
+    "toStringTag",
+    "value",
+    "t",
+    "mode",
+    "__esModule",
+    "ns",
+    "create",
+    "key",
+    "bind",
+    "n",
+    "object",
+    "property",
+    "prototype",
+    "hasOwnProperty",
+    "p",
+    "s",
+    "console",
+    "log",
+    "b"
+  ],
+  "mappings": "aACE,IAAIA,EAAmB,GAGvB,SAASC,EAAoBC,GAG5B,GAAGF,EAAiBE,GACnB,OAAOF,EAAiBE,GAAUC,QAGnC,IAAIC,EAASJ,EAAiBE,GAAY,CACzCG,EAAGH,EACHI,GAAG,EACHH,QAAS,IAUV,OANAI,EAAQL,GAAUM,KAAKJ,EAAOD,QAASC,EAAQA,EAAOD,QAASF,GAG/DG,EAAOE,GAAI,EAGJF,EAAOD,QAKfF,EAAoBQ,EAAIF,EAGxBN,EAAoBS,EAAIV,EAGxBC,EAAoBU,EAAI,SAASR,EAASS,EAAMC,GAC3CZ,EAAoBa,EAAEX,EAASS,IAClCG,OAAOC,eAAeb,EAASS,EAAM,CAAEK,YAAY,EAAMC,IAAKL,KAKhEZ,EAAoBkB,EAAI,SAAShB,GACX,oBAAXiB,QAA0BA,OAAOC,aAC1CN,OAAOC,eAAeb,EAASiB,OAAOC,YAAa,CAAEC,MAAO,WAE7DP,OAAOC,eAAeb,EAAS,aAAc,CAAEmB,OAAO,KAQvDrB,EAAoBsB,EAAI,SAASD,EAAOE,GAEvC,GADU,EAAPA,IAAUF,EAAQrB,EAAoBqB,IAC/B,EAAPE,EAAU,OAAOF,EACpB,GAAW,EAAPE,GAA8B,iBAAVF,GAAsBA,GAASA,EAAMG,WAAY,OAAOH,EAChF,IAAII,EAAKX,OAAOY,OAAO,MAGvB,GAFA1B,EAAoBkB,EAAEO,GACtBX,OAAOC,eAAeU,EAAI,UAAW,CAAET,YAAY,EAAMK,MAAOA,IACtD,EAAPE,GAA4B,iBAATF,EAAmB,IAAI,IAAIM,KAAON,EAAOrB,EAAoBU,EAAEe,EAAIE,EAAK,SAASA,GAAO,OAAON,EAAMM,IAAQC,KAAK,KAAMD,IAC9I,OAAOF,GAIRzB,EAAoB6B,EAAI,SAAS1B,GAChC,IAAIS,EAAST,GAAUA,EAAOqB,WAC7B,WAAwB,OAAOrB,EAAgB,SAC/C,WAA8B,OAAOA,GAEtC,OADAH,EAAoBU,EAAEE,EAAQ,IAAKA,GAC5BA,GAIRZ,EAAoBa,EAAI,SAASiB,EAAQC,GAAY,OAAOjB,OAAOkB,UAAUC,eAAe1B,KAAKuB,EAAQC,IAGzG/B,EAAoBkC,EAAI,GAIjBlC,EAAoBA,EAAoBmC,EAAI,G,gBC7ErDhC,EAAOD,QAAU,WAEfkC,QAAQC,IAAIC",
+  "file": "main.fa5a416a70ded1ab6043.js",
+  "sourcesContent": [
+    " \\t// The module cache\\n \\tvar installedModules = {};\\n\\n \\t// The require function\\n \\tfunction __webpack_require__(moduleId) {\\n\\n \\t\\t// Check if module is in cache\\n \\t\\tif(installedModules[moduleId]) {\\n \\t\\t\\treturn installedModules[moduleId].exports;\\n \\t\\t}\\n \\t\\t// Create a new module (and put it into the cache)\\n \\t\\tvar module = installedModules[moduleId] = {\\n \\t\\t\\ti: moduleId,\\n \\t\\t\\tl: false,\\n \\t\\t\\texports: {}\\n \\t\\t};\\n\\n \\t\\t// Execute the module function\\n \\t\\tmodules[moduleId].call(module.exports, module, module.exports, __webpack_require__);\\n\\n \\t\\t// Flag the module as loaded\\n \\t\\tmodule.l = true;\\n\\n \\t\\t// Return the exports of the module\\n \\t\\treturn module.exports;\\n \\t}\\n\\n\\n \\t// expose the modules object (__webpack_modules__)\\n \\t__webpack_require__.m = modules;\\n\\n \\t// expose the module cache\\n \\t__webpack_require__.c = installedModules;\\n\\n \\t// define getter function for harmony exports\\n \\t__webpack_require__.d = function(exports, name, getter) {\\n \\t\\tif(!__webpack_require__.o(exports, name)) {\\n \\t\\t\\tObject.defineProperty(exports, name, { enumerable: true, get: getter });\\n \\t\\t}\\n \\t};\\n\\n \\t// define __esModule on exports\\n \\t__webpack_require__.r = function(exports) {\\n \\t\\tif(typeof Symbol !== 'undefined' && Symbol.toStringTag) {\\n \\t\\t\\tObject.defineProperty(exports, Symbol.toStringTag, { value: 'Module' });\\n \\t\\t}\\n \\t\\tObject.defineProperty(exports, '__esModule', { value: true });\\n \\t};\\n\\n \\t// create a fake namespace object\\n \\t// mode & 1: value is a module id, require it\\n \\t// mode & 2: merge all properties of value into the ns\\n \\t// mode & 4: return value when already ns object\\n \\t// mode & 8|1: behave like require\\n \\t__webpack_require__.t = function(value, mode) {\\n \\t\\tif(mode & 1) value = __webpack_require__(value);\\n \\t\\tif(mode & 8) return value;\\n \\t\\tif((mode & 4) && typeof value === 'object' && value && value.__esModule) return value;\\n \\t\\tvar ns = Object.create(null);\\n \\t\\t__webpack_require__.r(ns);\\n \\t\\tObject.defineProperty(ns, 'default', { enumerable: true, value: value });\\n \\t\\tif(mode & 2 && typeof value != 'string') for(var key in value) __webpack_require__.d(ns, key, function(key) { return value[key]; }.bind(null, key));\\n \\t\\treturn ns;\\n \\t};\\n\\n \\t// getDefaultExport function for compatibility with non-harmony modules\\n \\t__webpack_require__.n = function(module) {\\n \\t\\tvar getter = module && module.__esModule ?\\n \\t\\t\\tfunction getDefault() { return module['default']; } :\\n \\t\\t\\tfunction getModuleExports() { return module; };\\n \\t\\t__webpack_require__.d(getter, 'a', getter);\\n \\t\\treturn getter;\\n \\t};\\n\\n \\t// Object.prototype.hasOwnProperty.call\\n \\t__webpack_require__.o = function(object, property) { return Object.prototype.hasOwnProperty.call(object, property); };\\n\\n \\t// __webpack_public_path__\\n \\t__webpack_require__.p = \\"\\";\\n\\n\\n \\t// Load entry module and return exports\\n \\treturn __webpack_require__(__webpack_require__.s = 0);\\n",
+    "// foo\\n/* @preserve*/\\n// bar\\nvar a = 2 + 2;\\n\\nmodule.exports = function Foo() {\\n  var b = 2 + 2;\\n  console.log(b + 1 + 2);\\n};\\n"
+  ],
+  "sourceRoot": ""
+}
+`;
 
 exports[`when options.sourceMap matches snapshot for a single \`true\` value (\`devtool\` is \`source-map\`): warnings 1`] = `Array []`;
diff --git a/test/__snapshots__/worker.test.js.snap b/test/__snapshots__/worker.test.js.snap
@@ -55,7 +55,7 @@ Object {
   "code": "function foo(f){if(f)return bar()}",
   "error": undefined,
   "extractedComments": Array [],
-  "map": "{\\"version\\":3,\\"sources\\":[\\"test1.js\\"],\\"names\\":[\\"foo\\",\\"x\\",\\"not_called1\\"],\\"mappings\\":\\"AAAA,SAASA,IAAIC,GACT,GACIA,EAAA,OACAC\\"}",
+  "map": "{\\"version\\":3,\\"sources\\":[\\"test6.js\\"],\\"names\\":[\\"foo\\",\\"x\\",\\"bar\\"],\\"mappings\\":\\"AAAA,SAASA,IAAIC,GAAK,GAAIA,EAAK,OAAOC\\"}",
   "warnings": undefined,
 }
 `;
diff --git a/test/sourceMap-option.test.js b/test/sourceMap-option.test.js
@@ -2,6 +2,22 @@ import UglifyJsPlugin from '../src/index';
 
 import { createCompiler, compile, cleanErrorStack } from './helpers';
 
+expect.addSnapshotSerializer({
+  test: (value) => {
+    // For string that are valid JSON
+    if (typeof value !== 'string') {
+      return false;
+    }
+
+    try {
+      return typeof JSON.parse(value) === 'object';
+    } catch (e) {
+      return false;
+    }
+  },
+  print: (value) => JSON.stringify(JSON.parse(value), null, 2),
+});
+
 describe('when options.sourceMap', () => {
   it('matches snapshot for a single `false` value (`devtool` is `source-map`)', () => {
     const compiler = createCompiler({

Original file line number	Diff line number	Diff line change
`@@ -55,7 +55,7 @@ Object {`
`55`	`55`	`"code": "function foo(f){if(f)return bar()}",`
`56`	`56`	`"error": undefined,`
`57`	`57`	`"extractedComments": Array [],`
`58`		`- "map": "{\\"version\\":3,\\"sources\\":[\\"test1.js\\"],\\"names\\":[\\"foo\\",\\"x\\",\\"not_called1\\"],\\"mappings\\":\\"AAAA,SAASA,IAAIC,GACT,GACIA,EAAA,OACAC\\"}",`
	`58`	`+ "map": "{\\"version\\":3,\\"sources\\":[\\"test6.js\\"],\\"names\\":[\\"foo\\",\\"x\\",\\"bar\\"],\\"mappings\\":\\"AAAA,SAASA,IAAIC,GAAK,GAAIA,EAAK,OAAOC\\"}",`
`59`	`59`	`"warnings": undefined,`
`60`	`60`	`}`
`61`	`61`	`;