Fix default messages extractor bug with line break escaping (elastic#…

…22140)

* Fix default messages extractor bug with line break escaping

* Change test case

src/dev/i18n/__snapshots__/utils.test.js.snap

@@ -0,0 +1,3 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`i18n utils should escape linebreaks 1`] = `"Text with\\\\n\\\\n\\\\nline-breaks and \\\\n\\\\n\\\\n      \\\\n\\\\n\\\\n      "`;

src/dev/i18n/utils.js

@@ -31,6 +31,7 @@ import { promisify } from 'util';
 const ESCAPE_LINE_BREAK_REGEX = /(?<!\\)\\\n/g;
 const ESCAPE_SINGLE_QUOTE_REGEX = /\\([\s\S])|(')/g;
 const HTML_LINE_BREAK_REGEX = /[\s]*\n[\s]*/g;
+const LINE_BREAK_REGEX = /\n/g;
 
 export const readFileAsync = promisify(fs.readFile);
 export const writeFileAsync = promisify(fs.writeFile);
@@ -63,7 +64,7 @@ export function formatJSString(string) {
   return (string || '')
     .replace(ESCAPE_LINE_BREAK_REGEX, '')
     .replace(ESCAPE_SINGLE_QUOTE_REGEX, '\\$1$2')
-    .replace('\n', '\\n');
+    .replace(LINE_BREAK_REGEX, '\\n');
 }
 
 export function formatHTMLString(string) {

src/dev/i18n/utils.test.js

@@ -45,6 +45,17 @@ describe('i18n utils', () => {
     expect(formatJSString('Test\\\n str\\\ning')).toEqual('Test string');
   });
 
+  test('should escape linebreaks', () => {
+    expect(
+      formatJSString(`Text with
+
+
+line-breaks and \n\n
+      \n\n
+      `)
+    ).toMatchSnapshot();
+  });
+
   test('should detect i18n translate function call', () => {
     let source = i18nTranslateSources[0];
     let expressionStatementNode = [...traverseNodes(parse(source).program.body)].find(node =>