i18n: introduce script to swap in new locale to LHR

lighthouse-core/lib/i18n/i18n.js

@@ -168,20 +168,21 @@ const _icuMessageInstanceMap = new Map();
  *
  * @param {LH.Locale} locale
  * @param {string} icuMessageId
- * @param {string} icuMessage
+ * @param {string=} fallbackMessage
  * @param {*} [values]
  * @return {{formattedString: string, icuMessage: string}}
  */
-function _formatIcuMessage(locale, icuMessageId, icuMessage, values) {
+function _formatIcuMessage(locale, icuMessageId, fallbackMessage, values) {
   const localeMessages = LOCALES[locale];
   const localeMessage = localeMessages[icuMessageId] && localeMessages[icuMessageId].message;
   // fallback to the original english message if we couldn't find a message in the specified locale
   // better to have an english message than no message at all, in some number cases it won't even matter
-  const messageForMessageFormat = localeMessage || icuMessage;
+  const messageForMessageFormat = localeMessage || fallbackMessage;
+  if (messageForMessageFormat === undefined) throw new Error('No ICU message string to format');
   // when using accented english, force the use of a different locale for number formatting
   const localeForMessageFormat = locale === 'en-XA' ? 'de-DE' : locale;
   // pre-process values for the message format like KB and milliseconds
-  const valuesForMessageFormat = _preprocessMessageValues(icuMessage, values);
+  const valuesForMessageFormat = _preprocessMessageValues(messageForMessageFormat, values);
 
   const formatter = new MessageFormat(messageForMessageFormat, localeForMessageFormat, formats);
   const formattedString = formatter.format(valuesForMessageFormat);
@@ -277,6 +278,20 @@ function getFormatted(icuMessageIdOrRawString, locale) {
   return icuMessageIdOrRawString;
 }
 
+/**
+ * @param {LH.Locale} locale
+ * @param {string} icuMessageId
+ * @param {*} [values]
+ * @return {string}
+ */
+function getFormattedFromIdAndValues(locale, icuMessageId, values) {
+  const icuMessageIdRegex = /(.* \| .*)$/;
+  if (!icuMessageIdRegex.test(icuMessageId)) throw new Error('This is not an ICU message ID');
+
+  const {formattedString} = _formatIcuMessage(locale, icuMessageId, undefined, values);
+  return formattedString;
+}
+
 /**
  * @param {string} icuMessageInstanceId
  * @param {LH.Locale} locale
@@ -349,6 +364,7 @@ module.exports = {
   getRendererFormattedStrings,
   createMessageInstanceIdFn,
   getFormatted,
+  getFormattedFromIdAndValues,
   replaceIcuMessageInstanceIds,
   isIcuMessage,
 };

lighthouse-core/lib/i18n/swap-locale.js

@@ -0,0 +1,95 @@
+/**
+ * @license Copyright 2019 Google Inc. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
+ */
+'use strict';
+
+/* eslint-disable no-console, max-len */
+
+const _set = require('lodash.set');
+
+const i18n = require('./i18n.js');
+
+/**
+ * @fileoverview Use the lhr.i18n.icuMessagePaths object to change locales
+ *
+ * `icuMessagePaths` is an object keyed by `icuMessageId`s. Within each is either
+ * 1) an array of strings, which are just object paths to where that message is used in the LHR
+ * 2) an array of `LH.I18NMessageValuesEntry`s which include both a `path` and a `values` object
+ *    which will be used in the replacement within `i18n._formatIcuMessage()`
+ *
+ * An example:
+    "icuMessagePaths": {
+    "lighthouse-core/audits/metrics/first-contentful-paint.js | title": [
+      "audits[first-contentful-paint].title"
+    ],
+    "lighthouse-core/audits/time-to-first-byte.js | displayValue": [
+      {
+        "values": {
+          "timeInMs": 570.5630000000001
+        },
+        "path": "audits[time-to-first-byte].displayValue"
+      }
+    ],
+    "lighthouse-core/lib/i18n/i18n.js | columnTimeSpent": [
+      "audits[mainthread-work-breakdown].details.headings[1].text",
+      "audits[network-rtt].details.headings[1].text",
+      "audits[network-server-latency].details.headings[1].text"
+    ],
+    ...
+ */
+
+/**
+ * Returns a new LHR with all strings changed to the new `requestedLocale`.
+ * @param {LH.Result} lhr
+ * @param {LH.Locale} requestedLocale
+ * @return {LH.Result}
+ */
+function swapLocale(lhr, requestedLocale) {
+  // Copy LHR to avoid mutating provided LHR.
+  lhr = JSON.parse(JSON.stringify(lhr));
+
+  const locale = i18n.lookupLocale(requestedLocale);
+  const {icuMessagePaths} = lhr.i18n;
+  const missingIcuMessageIds = /** @type {string[]} */([]);
+
+  Object.entries(icuMessagePaths).forEach(([icuMessageId, messageInstancesInLHR]) => {
+    for (const instance of messageInstancesInLHR) {
+      // The path that _formatPathAsString() generated
+      let path;
+      let values;
+      if (typeof instance === 'string') {
+        path = instance;
+      } else {
+        path = instance.path;
+        // `values` are the string template values to be used. eg. `values: {wastedBytes: 9028}`
+        values = instance.values;
+      }
+      // If we couldn't find the new replacement message, keep things as is.
+      try {
+        // Get new formatted strings in revised locale
+        const formattedStr = i18n.getFormattedFromIdAndValues(locale, icuMessageId, values);
+        // Write string back into the LHR
+        _set(lhr, path, formattedStr);
+      } catch (err) {
+        if (err.message === 'No ICU message string to format') {
+          missingIcuMessageIds.push(icuMessageId);
+        } else {
+          throw err;
+        }
+      }
+    }
+  });
+
+  if (missingIcuMessageIds.length) {
+    console.error(`No message in locale (${locale}) found for:\n`, missingIcuMessageIds);
+  }
+
+  lhr.i18n.rendererFormattedStrings = i18n.getRendererFormattedStrings(locale);
+  // Tweak the config locale
+  lhr.configSettings.locale = locale;
+  return lhr;
+}
+
+module.exports = swapLocale;

lighthouse-core/test/lib/i18n/swap-locale-test.js

@@ -0,0 +1,48 @@
+/**
+ * @license Copyright 2019 Google Inc. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
+ */
+'use strict';
+
+const swapLocale = require('../../../lib/i18n/swap-locale.js');
+
+const lhr = require('../../results/sample_v2.json');
+
+/* eslint-env jest */
+beforeEach(() => {
+  // silence console.error spam about messages not found
+  // eslint-disable-next-line no-console
+  console.error = jest.fn();
+});
+
+describe('swap-locale', () => {
+  it('can change golden LHR english strings into spanish', () => {
+    const lhrEn = /** @type {LH.Result} */ (JSON.parse(JSON.stringify(lhr)));
+    const lhrEs = swapLocale(lhrEn, 'es');
+
+    // Basic replacement
+    expect(lhrEn.audits.plugins.title).toEqual('Document avoids plugins');
+    expect(lhrEs.audits.plugins.title).toEqual('El documento no usa complementos');
+
+    // With ICU string argument values
+    expect(lhrEn.audits['dom-size'].displayValue).toEqual('31 elements');
+    expect(lhrEs.audits['dom-size'].displayValue).toEqual('31 elementos');
+
+    // Renderer formatted strings
+    expect(lhrEn.i18n.rendererFormattedStrings.labDataTitle).toEqual('Lab Data');
+    expect(lhrEs.i18n.rendererFormattedStrings.labDataTitle).toEqual('Datos de prueba');
+  });
+
+  it('can roundtrip back to english correctly', () => {
+    const lhrEn = /** @type {LH.Result} */ (JSON.parse(JSON.stringify(lhr)));
+
+    // via Spanish
+    const lhrEnEsRT = swapLocale(swapLocale(lhrEn, 'es'), 'en-US');
+    expect(lhrEnEsRT).toMatchObject(lhrEn);
+
+    // via Arabic
+    const lhrEnArRT = swapLocale(swapLocale(lhrEn, 'ar'), 'en-US');
+    expect(lhrEnArRT).toMatchObject(lhrEn);
+  });
+});

package.json

@@ -82,6 +82,7 @@
     "@types/jest": "^24.0.9",
     "@types/jpeg-js": "^0.3.0",
     "@types/lodash.isequal": "^4.5.2",
+    "@types/lodash.set": "^4.3.6",
     "@types/make-dir": "^1.0.3",
     "@types/mkdirp": "^0.5.2",
     "@types/node": "*",
@@ -121,6 +122,7 @@
     "isomorphic-fetch": "^2.2.1",
     "jest": "^24.3.0",
     "jsdom": "^12.2.0",
+    "lodash.set": "^4.3.2",
     "make-dir": "^1.3.0",
     "npm-run-posix-or-windows": "^2.0.2",
     "nyc": "^13.3.0",

types/lhr.d.ts

@@ -8,7 +8,8 @@ import LHError = require('../lighthouse-core/lib/lh-error.js');
 
 declare global {
   module LH {
-    export type I18NMessageEntry = string | {path: string, values: any};
+    export type I18NMessageValuesEntry = {path: string, values:  Record<string, string | number>};
+    export type I18NMessageEntry = string | I18NMessageValuesEntry;
 
     export interface I18NMessages {
       [icuMessageId: string]: I18NMessageEntry[];

yarn.lock

@@ -541,6 +541,13 @@
   dependencies:
     "@types/lodash" "*"
 
+"@types/lodash.set@^4.3.6":
+  version "4.3.6"
+  resolved "https://registry.yarnpkg.com/@types/lodash.set/-/lodash.set-4.3.6.tgz#33e635c2323f855359225df6a5c8c6f1f1908264"
+  integrity sha512-ZeGDDlnRYTvS31Laij0RsSaguIUSBTYIlJFKL3vm3T2OAZAQj2YpSvVWJc0WiG4jqg9fGX6PAPGvDqBcHfSgFg==
+  dependencies:
+    "@types/lodash" "*"
+
 "@types/lodash@*":
   version "4.14.106"
   resolved "https://registry.yarnpkg.com/@types/lodash/-/lodash-4.14.106.tgz#6093e9a02aa567ddecfe9afadca89e53e5dce4dd"
@@ -5602,6 +5609,11 @@ lodash.memoize@~3.0.3:
   resolved "https://registry.yarnpkg.com/lodash.memoize/-/lodash.memoize-3.0.4.tgz#2dcbd2c287cbc0a55cc42328bd0c736150d53e3f"
   integrity sha1-LcvSwofLwKVcxCMovQxzYVDVPj8=
 
+lodash.set@^4.3.2:
+  version "4.3.2"
+  resolved "https://registry.yarnpkg.com/lodash.set/-/lodash.set-4.3.2.tgz#d8757b1da807dde24816b0d6a84bea1a76230b23"
+  integrity sha1-2HV7HagH3eJIFrDWqEvqGnYjCyM=
+
 lodash.sortby@^4.7.0:
   version "4.7.0"
   resolved "https://registry.yarnpkg.com/lodash.sortby/-/lodash.sortby-4.7.0.tgz#edd14c824e2cc9c1e0b0a1b42bb5210516a42438"