azure, utils: Improve and dedupe randomUtils (#1763)

utils/src/node/crypto.ts

@@ -5,4 +5,4 @@
 
 /* eslint-disable */
 import * as nodeCrypto from 'crypto';
-export const crypto = nodeCrypto.webcrypto as any;
+export const crypto = nodeCrypto.webcrypto;

utils/src/utils/randomUtils.ts

@@ -18,7 +18,13 @@ export namespace randomUtils {
     }
 
     export function getRandomHexString(length: number = 6): string {
-        return crypto.randomUUID().slice(0, length);
+        if (length <= 0) {
+            throw new Error(`Length must be strictly positive`);
+        }
+
+        const array = new Uint8Array(Math.ceil(length / 2)); // Each byte is represented by 2 hex characters
+        crypto.getRandomValues(array);
+        return Buffer.from(array).toString('hex').slice(0, length);
     }
 
     export function getRandomInteger(minimumInclusive: number, maximumExclusive: number): number {

utils/test/randomUtils.test.ts

@@ -0,0 +1,21 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import assert = require('assert');
+import { randomUtils } from '../src/utils/randomUtils';
+
+
+suite('randomUtils', function (this: Mocha.Suite): void {
+    test('getRandomHexString', async () => {
+        // An even number length
+        assert.strictEqual(randomUtils.getRandomHexString(6).length, 6);
+
+        // An odd number length
+        assert.strictEqual(randomUtils.getRandomHexString(5).length, 5);
+
+        // Zero length should throw
+        assert.throws(() => randomUtils.getRandomHexString(0));
+    });
+});