[IMP] web: Ensure array utility function

This commit introduces the `ensureArray` function, ensuring that the
given argument is an array by wrapping it in one if it is not.

Part of task 3121497

Part-of: odoo/odoo#112171

addons/web/static/src/core/utils/arrays.js

@@ -53,6 +53,14 @@ function _getExtractorFrom(criterion) {
     }
 }
 
+/**
+ * @template T
+ * @param {T | T[]} value
+ */
+export function ensureArray(value) {
+    return value && typeof value === "object" && value[Symbol.iterator] ? [...value] : [value];
+}
+
 /**
  * Returns the array of elements contained in both arrays.
  *

addons/web/static/tests/core/utils/arrays_tests.js

@@ -2,6 +2,7 @@
 
 import {
     cartesian,
+    ensureArray,
     groupBy,
     intersection,
     shallowEqual,
@@ -238,6 +239,18 @@ QUnit.module("utils", () => {
         assert.deepEqual(cartesian([1], [2], [3], [4]), [[1, 2, 3, 4]]);
     });
 
+    QUnit.test("ensure array", async (assert) => {
+        const arrayRef = [];
+        assert.notEqual(ensureArray(arrayRef), arrayRef, "Should be a different array");
+        assert.deepEqual(ensureArray([]), []);
+        assert.deepEqual(ensureArray(), [undefined]);
+        assert.deepEqual(ensureArray(null), [null]);
+        assert.deepEqual(ensureArray({ a: 1 }), [{ a: 1 }]);
+        assert.deepEqual(ensureArray("foo"), ["foo"]);
+        assert.deepEqual(ensureArray([1, 2, "3"]), [1, 2, "3"]);
+        assert.deepEqual(ensureArray(new Set([1, 2, 3])), [1, 2, 3]);
+    });
+
     QUnit.test("unique array", function (assert) {
         assert.deepEqual(unique([1, 2, 3, 2, 4, 3, 1, 4]), [1, 2, 3, 4]);
         assert.deepEqual(unique("a d c a b c d b".split(" ")), "a d c b".split(" "));