Write tests for TextDictionary.js

This CL attempts to cover TextDictionary.js
with tests to help with debugging and releases

Change-Id: If733cc1c2baa2ab3006a40605ecb983b154c3e87
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1841634Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Paul Lewis <aerotwist@chromium.org>
Commit-Queue: Almothana Athamneh <almuthanna@google.com>
Cr-Commit-Position: refs/heads/master@{#704179}

third_party/blink/renderer/devtools/tests/front_end/common/TextDictionary.ts

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+const {assert} = chai;
+
+import {default as TextDictionary} from '../../../front_end/common/TextDictionary.js';
+import {default as Trie} from '../../../front_end/common/Trie.js';
+
+describe('Text Dictionary', () => {
+  it('can be created with its basic attributes', () => {
+    const textDic = new TextDictionary();
+    assert.instanceOf(textDic._words, Map, 'did not create a Map named _words');
+    assert.instanceOf(textDic._index, Trie, 'did not create a Trie named _index');
+  });
+
+  it('can add a word successfully', () => {
+    const textDic = new TextDictionary();
+    textDic.addWord('test');
+    assert.isTrue(textDic.hasWord('test'), 'word was not added successfully');
+  });
+
+  it('can remove a word successfully', () => {
+    const textDic = new TextDictionary();
+    textDic.addWord('test');
+    assert.isTrue(textDic.hasWord('test'), 'word was not added successfully');
+    textDic.removeWord('test');
+    assert.isFalse(textDic.hasWord('test'), 'word was not removed successfully');
+  });
+
+  it('returns nothing when trying to remove a word that does not exist', () => {
+    const textDic = new TextDictionary();
+    assert.isUndefined(
+        textDic.removeWord('test'), 'removeWord function did not return Undefined for a word not in the dictionaty');
+  });
+
+  it('removes a word that was added twice', () => {
+    const textDic = new TextDictionary();
+    textDic.addWord('test');
+    textDic.addWord('test');
+    assert.isTrue(textDic.hasWord('test'), 'words were not added successfully');
+    textDic.removeWord('test');
+    assert.isTrue(textDic.hasWord('test'), 'both words were removed');
+    textDic.removeWord('test');
+    assert.isFalse(textDic.hasWord('test'), 'the second word was not removed successfully');
+  });
+
+  it('retrieve words with a certain prefix', () => {
+    const textDic = new TextDictionary();
+    textDic.addWord('test');
+    textDic.addWord('ten');
+    textDic.addWord('nine');
+    const foundWords = textDic.wordsWithPrefix('te');
+    assert.equal(foundWords[0], 'test', 'first word was not retrieved');
+    assert.equal(foundWords[1], 'ten', 'second word was not retrieved');
+  });
+
+  it('retrieve the word count for a certain word', () => {
+    const textDic = new TextDictionary();
+    textDic.addWord('test');
+    textDic.addWord('test');
+    textDic.addWord('ten');
+    assert.equal(textDic.wordCount('test'), 2, 'word count is incorrect');
+  });
+
+  it('retrieve the word count for a certain word that is not in the dictionary', () => {
+    const textDic = new TextDictionary();
+    textDic.addWord('test');
+    textDic.addWord('test');
+    textDic.addWord('ten');
+    assert.equal(textDic.wordCount('testing'), 0, 'word count is incorrect');
+  });
+
+  it('reset the dictionary after adding words to it', () => {
+    const textDic = new TextDictionary();
+    textDic.addWord('test');
+    textDic.addWord('test');
+    textDic.addWord('ten');
+    textDic.reset();
+    assert.isFalse(textDic.hasWord('test'), 'first word still in the dictionary');
+    assert.isFalse(textDic.hasWord('ten'), 'second word still in the dictionary');
+    assert.equal(textDic.wordCount('test'), 0, 'first word still has a count');
+    assert.equal(textDic.wordCount('ten'), 0, 'second word still has a count');
+  });
+});