feat: ensureArray

Author: mshanemc

.mocharc.json

@@ -1,6 +1,7 @@
 {
   "require": "ts-node/register,source-map-support/register",
   "watch-extensions": "ts",
+  "watch-files": "src/**/*.ts, test/**/*.ts",
   "recursive": true,
   "reporter": "spec",
   "timeout": 5000

package.json

@@ -14,11 +14,11 @@
   ],
   "scripts": {
     "build": "sf-build",
+    "ci-docs": "yarn sf-ci-docs",
     "clean": "sf-clean",
     "clean-all": "sf-clean all",
     "compile": "sf-compile",
     "docs": "sf-docs",
-    "ci-docs": "yarn sf-ci-docs",
     "format": "sf-format",
     "lint": "sf-lint",
     "lint-fix": "yarn sf-lint --fix",

src/collections.ts

@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2022, salesforce.com, inc.
+ * All rights reserved.
+ * Licensed under the BSD 3-Clause license.
+ * For full license text, see LICENSE.txt file in the repo root or https://opensource.org/licenses/BSD-3-Clause
+ */
+
+/**
+ * Normalize an object to be an array if it isn't one.
+ *
+ * @param entryOrArray - An object that could be an array of its type or just its type
+ * @returns An array of the input element (which might be empty)
+ */
+
+export const ensureArray = <T>(entryOrArray: T | T[] | undefined): T[] => {
+  if (entryOrArray) {
+    return Array.isArray(entryOrArray) ? entryOrArray : [entryOrArray];
+  }
+  return [];
+};

src/index.ts

@@ -11,3 +11,4 @@ export * from './env';
 export * from './errors';
 export * from './json';
 export * from './nodash';
+export * from './collections';

test/collections.test.ts

@@ -0,0 +1,25 @@
+/*
+ * Copyright (c) 2022, salesforce.com, inc.
+ * All rights reserved.
+ * Licensed under the BSD 3-Clause license.
+ * For full license text, see LICENSE.txt file in the repo root or https://opensource.org/licenses/BSD-3-Clause
+ */
+import { expect } from 'chai';
+import { ensureArray } from '../src/collections';
+
+describe('collections', () => {
+  describe('ensureArray', () => {
+    it('undefined => empty array', () => {
+      const input = undefined;
+      expect(ensureArray(input)).to.deep.equal([]);
+    });
+    it('an array => the array', () => {
+      const input = ['a', 'b'];
+      expect(ensureArray(input)).to.deep.equal(input);
+    });
+    it('a single item => obj in an array', () => {
+      const input = 'a';
+      expect(ensureArray(input)).to.deep.equal([input]);
+    });
+  });
+});