[I18n] Fix pseudo-localization of i18n directive placeholders

packages/kbn-i18n/src/core/__snapshots__/pseudo_locale.test.ts.snap

@@ -0,0 +1,7 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`translateUsingPseudoLocale() should translate @I18N@ placeholders with wrong reference name 1`] = `"Ṁéšššàĝĝé ŵîîţĥ àà @Î18Ñ@ññôñ-ššîñĝĝļé-ŵŵôŕðð@Î18Ñ@ þþļàççéĥôôļðééŕ."`;
+
+exports[`translateUsingPseudoLocale() shouldn't translate @I18N@ placeholders 1`] = `"Ṁéšššàĝĝé ŵîîţĥ àà @I18N@value@I18N@ þļààçéĥĥôļððéŕ."`;
+
+exports[`translateUsingPseudoLocale() shouldn't translate @I18N@ placeholders with underscore 1`] = `"Ṁéšššàĝĝé ŵîîţĥ àà @I18N@snake_case_value@I18N@ þļààçéĥĥôļððéŕ."`;

packages/kbn-i18n/src/core/pseudo_locale.test.ts

@@ -0,0 +1,40 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you 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.
+ */
+
+import { translateUsingPseudoLocale } from './pseudo_locale';
+
+describe('translateUsingPseudoLocale()', () => {
+  it(`shouldn't translate @I18N@ placeholders`, () => {
+    const message = 'Message with a @I18N@value@I18N@ placeholder.';
+
+    expect(translateUsingPseudoLocale(message)).toMatchSnapshot();
+  });
+
+  it(`shouldn't translate @I18N@ placeholders with underscore`, () => {
+    const message = 'Message with a @I18N@snake_case_value@I18N@ placeholder.';
+
+    expect(translateUsingPseudoLocale(message)).toMatchSnapshot();
+  });
+
+  it(`should translate @I18N@ placeholders with wrong reference name`, () => {
+    const message = 'Message with a @I18N@non-single-word@I18N@ placeholder.';
+
+    expect(translateUsingPseudoLocale(message)).toMatchSnapshot();
+  });
+});

packages/kbn-i18n/src/core/pseudo_locale.ts

@@ -18,9 +18,9 @@
  */
 
 /**
- * Matches every single [A-Za-z] character, `<tag attr="any > text">` and `](markdown-link-address)`
+ * Matches every single [A-Za-z] character, `<tag attr="any > text">`, `](markdown-link-address)` and `@I18N@valid_variable_name@I18N@`
  */
-const CHARS_FOR_PSEUDO_LOCALIZATION_REGEX = /[A-Za-z]|(\]\([\s\S]*?\))|(<([^"<>]|("[^"]*?"))*?>)/g;
+const CHARS_FOR_PSEUDO_LOCALIZATION_REGEX = /[A-Za-z]|(\]\([\s\S]*?\))|(<([^"<>]|("[^"]*?"))*?>)|(@I18N@\w*?@I18N@)/g;
 const PSEUDO_ACCENTS_LOCALE = 'en-xa';
 
 export function isPseudoLocale(locale: string) {