Unit tests for isHTMLBRElement

Summary: Adds a unit test for isHTMLBRElement, for the cases null, same document, iframed document

Reviewed By: mrkev

Differential Revision: D18831442

fbshipit-source-id: af4702f25f7a28cc786078e770023e1c44fdb674

Author: Claudio Procida

src/component/utils/__tests__/isHTMLBRElement-test.js

@@ -0,0 +1,33 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails oncall+draft-js
+ * @flow strict-local
+ * @format
+ */
+
+'use strict';
+
+const isHTMLBRElement = require('isHTMLBRElement');
+
+test('isHTMLBRElement recognizes null', () => {
+  expect(isHTMLBRElement(null)).toBe(false);
+});
+
+test('isHTMLBRElement recognizes BR elements in same document', () => {
+  const br = document.createElement('br');
+  expect(isHTMLBRElement(br)).toBe(true);
+});
+
+test('isHTMLBRElement recognizes BR elements in iframed document', () => {
+  const iframe = document.createElement('iframe');
+  if (document.body != null) {
+    document.body.appendChild(iframe);
+    const doc = iframe.contentDocument;
+    const br = doc.createElement('br');
+    expect(isHTMLBRElement(br)).toBe(true);
+  }
+});