tests(i18n): throw when no ICU replacement value is given (#9384)

lighthouse-core/lib/i18n/i18n.js

@@ -127,17 +127,15 @@ function lookupLocale(locale) {
  * @param {string} icuMessage
  * @param {Record<string, *>} [values]
  */
-function _preprocessMessageValues(icuMessage, values) {
-  if (!values) return;
-
+function _preprocessMessageValues(icuMessage, values = {}) {
   const clonedValues = JSON.parse(JSON.stringify(values));
   const parsed = MessageParser.parse(icuMessage);
   // Throw an error if a message's value isn't provided
   parsed.elements
     .filter(el => el.type === 'argumentElement')
     .forEach(el => {
       if (el.id && (el.id in values) === false) {
-        throw new Error('ICU Message contains a value reference that wasn\'t provided');
+        throw new Error(`ICU Message contains a value reference ("${el.id}") that wasn't provided`);
       }
     });
 

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

@@ -102,6 +102,7 @@ describe('i18n', () => {
       helloSecWorld: 'Hello {in, number, seconds} World',
       helloTimeInMsWorld: 'Hello {timeInMs, number, seconds} World',
       helloPercentWorld: 'Hello {in, number, extendedPercent} World',
+      helloWorldMultiReplace: '{hello} {world}',
     };
     const str_ = i18n.createMessageInstanceIdFn(__filename, UIStrings);
 
@@ -134,5 +135,16 @@ describe('i18n', () => {
       const helloPercentStr = str_(UIStrings.helloPercentWorld, {in: 0.43078});
       expect(helloPercentStr).toBeDisplayString('Hello 43.08% World');
     });
+
+    it('throws an error when values are needed but not provided', () => {
+      expect(_ => i18n.getFormatted(str_(UIStrings.helloBytesWorld), 'en-US'))
+      .toThrow(`ICU Message contains a value reference ("in") that wasn't provided`);
+    });
+
+    it('throws an error when a value is missing', () => {
+      expect(_ => i18n.getFormatted(str_(UIStrings.helloWorldMultiReplace,
+        {hello: 'hello'}), 'en-US'))
+      .toThrow(`ICU Message contains a value reference ("world") that wasn't provided`);
+    });
   });
 });