Add real provider for i18nProvider mock (#181025)

## Summary

Fix #180725

packages/core/i18n/core-i18n-browser-mocks/src/i18n_context_mock.test.tsx

@@ -0,0 +1,34 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import React from 'react';
+import { FormattedMessage } from '@kbn/i18n-react';
+import { I18nProviderMock } from './i18n_context_mock';
+import { shallow } from 'enzyme';
+
+describe('I18nProviderMock', () => {
+  it('interpolates to default message if present', () => {
+    expect(
+      shallow(
+        <I18nProviderMock>
+          <FormattedMessage id="id" defaultMessage="default message" />
+        </I18nProviderMock>
+      ).html()
+    ).toMatchInlineSnapshot(`"default message"`);
+  });
+
+  it('interpolates to id if default message is not present', () => {
+    expect(
+      shallow(
+        <I18nProviderMock>
+          <FormattedMessage id="id" />
+        </I18nProviderMock>
+      ).html()
+    ).toMatchInlineSnapshot(`"id"`);
+  });
+});

packages/core/i18n/core-i18n-browser-mocks/src/i18n_context_mock.tsx

@@ -0,0 +1,28 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+import React from 'react';
+// eslint-disable-next-line @kbn/eslint/module_migration
+import { IntlProvider } from 'react-intl';
+import { i18n } from '@kbn/i18n';
+
+const emptyMessages = {};
+
+export const I18nProviderMock: React.FC = ({ children }) => {
+  return (
+    <IntlProvider
+      locale={i18n.getLocale()}
+      messages={emptyMessages}
+      defaultLocale={i18n.getLocale()}
+      formats={i18n.getFormats()}
+      textComponent={React.Fragment}
+    >
+      {children}
+    </IntlProvider>
+  );
+};

packages/core/i18n/core-i18n-browser-mocks/src/i18n_service.mock.ts

@@ -6,17 +6,15 @@
  * Side Public License, v 1.
  */
 
-import React from 'react';
 import type { PublicMethodsOf } from '@kbn/utility-types';
-import { I18nService } from '@kbn/core-i18n-browser-internal';
+import type { I18nService } from '@kbn/core-i18n-browser-internal';
 import type { I18nStart } from '@kbn/core-i18n-browser';
-
-const PassThroughComponent = ({ children }: { children: React.ReactNode }) => children;
+import { I18nProviderMock } from './i18n_context_mock';
 
 const createStartContractMock = () => {
   const setupContract: jest.Mocked<I18nStart> = {
-    // By default mock the Context component so it simply renders all children
-    Context: jest.fn().mockImplementation(PassThroughComponent),
+    // Stubbed provider returning the default message or id
+    Context: jest.fn().mockImplementation(I18nProviderMock),
   };
   return setupContract;
 };

packages/core/i18n/core-i18n-browser-mocks/tsconfig.json

@@ -8,12 +8,15 @@
     ]
   },
   "include": [
-    "**/*.ts"
+    "**/*.ts",
+    "**/*.tsx"
   ],
   "kbn_references": [
     "@kbn/utility-types",
     "@kbn/core-i18n-browser",
-    "@kbn/core-i18n-browser-internal"
+    "@kbn/core-i18n-browser-internal",
+    "@kbn/i18n-react",
+    "@kbn/i18n"
   ],
   "exclude": [
     "target/**/*",