feat(curriculum): update lunch picker test to prevent mutation (#60145)

Co-authored-by: Ilenia <26656284+ilenia-magoni@users.noreply.github.com>

curriculum/challenges/english/25-front-end-development/lab-lunch-picker-program/66db529d37ad966480ebb633.md

@@ -307,29 +307,57 @@ const temp = console.log;
 
 try {
   console.log = obj => tempArr.push(obj);
-
   // check that it correctly outputs the first item
   Math.random = () => 0;
-  getRandomLunch(testLunches);
+  getRandomLunch([...testLunches]);
   assert.strictEqual(tempArr[0], `Randomly selected lunch: ${testLunches[0]}`);
 
-  // second item
+  // Second item
   Math.random = () => 0.4;
-  getRandomLunch(testLunches);
+  getRandomLunch([...testLunches]);
   assert.strictEqual(tempArr[1], `Randomly selected lunch: ${testLunches[1]}`);
 
-  // third item
+  // Third item
   Math.random = () => 0.8;
-  getRandomLunch(testLunches);
+  getRandomLunch([...testLunches]);
   assert.strictEqual(tempArr[2], `Randomly selected lunch: ${testLunches[2]}`);
 
 } finally {
-  // restore Math.random
   Math.random = tempRandom;
   console.log = temp;
 }
 ```
 
+The `getRandomLunch` function should not change the array passed to it as argument.
+
+```js
+const testLunches = ["Fish", "Fries", "Roast"];
+let originalLunches = [...testLunches];
+const tempRandom = Math.random;
+
+try {
+  Math.random = () => 0;
+  getRandomLunch(testLunches);
+  assert.sameOrderedMembers(testLunches, originalLunches);
+
+  Math.random = () => 0.4;
+  getRandomLunch(testLunches);
+  assert.sameOrderedMembers(testLunches, originalLunches);
+
+  Math.random = () => 0.8;
+  getRandomLunch(testLunches);
+  assert.sameOrderedMembers(testLunches, originalLunches);
+
+  const emptyLunches = [];
+  let originalEmpty = [...emptyLunches];
+  getRandomLunch(emptyLunches);
+  assert.sameOrderedMembers(emptyLunches, originalEmpty);
+
+} finally {
+  Math.random = tempRandom;
+}
+```
+
 You should define a function `showLunchMenu`.
 
 ```js