fix(localize): render location in XLIFF 2 even if there is no metadata

Previously, the location of a translation message, in XLIFF 2, was only
rendered if there were also notes for meaning or description. Now the
location will be rendered even if the other metadata is not provided.

Fixes angular#38705

packages/localize/src/tools/src/extract/translation_files/xliff2_translation_serializer.ts

@@ -51,7 +51,7 @@ export class Xliff2TranslationSerializer implements TranslationSerializer {
       }
       ids.add(id);
       xml.startTag('unit', {id});
-      if (message.meaning || message.description) {
+      if (message.meaning || message.description || message.location) {
         xml.startTag('notes');
         if (message.location) {
           const {file, start, end} = message.location;

packages/localize/src/tools/test/extract/translation_files/xliff1_translation_serializer_spec.ts

@@ -49,6 +49,13 @@ runInEachFileSystem(() => {
             mockMessage(
                 '67890', ['a', '', 'c'], ['START_TAG_SPAN', 'CLOSE_TAG_SPAN'],
                 {description: 'some description'}),
+            mockMessage('38705', ['a', '', 'c'], ['START_TAG_SPAN', 'CLOSE_TAG_SPAN'], {
+              location: {
+                file: absoluteFrom('/project/file.ts'),
+                start: {line: 2, column: 7},
+                end: {line: 3, column: 2}
+              }
+            }),
             mockMessage('13579', ['', 'b', ''], ['START_BOLD_TEXT', 'CLOSE_BOLD_TEXT'], {}),
             mockMessage('24680', ['a'], [], {meaning: 'meaning', description: 'and description'}),
             mockMessage('80808', ['multi\nlines'], [], {}),
@@ -91,6 +98,13 @@ runInEachFileSystem(() => {
             `        <source>a<x id="START_TAG_SPAN"/><x id="CLOSE_TAG_SPAN"/>c</source>`,
             `        <note priority="1" from="description">some description</note>`,
             `      </trans-unit>`,
+            `      <trans-unit id="38705" datatype="html">`,
+            `        <source>a<x id="START_TAG_SPAN"/><x id="CLOSE_TAG_SPAN"/>c</source>`,
+            `        <context-group purpose="location">`,
+            `          <context context-type="sourcefile">file.ts</context>`,
+            `          <context context-type="linenumber">3,4</context>`,
+            `        </context-group>`,
+            `      </trans-unit>`,
             `      <trans-unit id="13579" datatype="html">`,
             `        <source><x id="START_BOLD_TEXT"/>b<x id="CLOSE_BOLD_TEXT"/></source>`,
             `      </trans-unit>`,

packages/localize/src/tools/test/extract/translation_files/xliff2_translation_serializer_spec.ts

@@ -54,6 +54,13 @@ runInEachFileSystem(() => {
                 end: {line: 3, column: 2}
               }
             }),
+            mockMessage('location-only', ['a', '', 'c'], ['START_TAG_SPAN', 'CLOSE_TAG_SPAN'], {
+              location: {
+                file: absoluteFrom('/project/file.ts'),
+                start: {line: 2, column: 7},
+                end: {line: 3, column: 2}
+              }
+            }),
             mockMessage('13579', ['', 'b', ''], ['START_BOLD_TEXT', 'CLOSE_BOLD_TEXT'], {}),
             mockMessage('24680', ['a'], [], {meaning: 'meaning', description: 'and description'}),
             mockMessage('80808', ['multi\nlines'], [], {}),
@@ -101,6 +108,14 @@ runInEachFileSystem(() => {
             `        <source>a<pc id="0" equivStart="START_TAG_SPAN" equivEnd="CLOSE_TAG_SPAN"></pc>c</source>`,
             `      </segment>`,
             `    </unit>`,
+            `    <unit id="location-only">`,
+            `      <notes>`,
+            `        <note category="location">file.ts:3,4</note>`,
+            `      </notes>`,
+            `      <segment>`,
+            `        <source>a<pc id="0" equivStart="START_TAG_SPAN" equivEnd="CLOSE_TAG_SPAN"></pc>c</source>`,
+            `      </segment>`,
+            `    </unit>`,
             `    <unit id="13579">`,
             `      <segment>`,
             `        <source><pc id="0" equivStart="START_BOLD_TEXT" equivEnd="CLOSE_BOLD_TEXT">b</pc></source>`,