Add test to ensure dedupe returns a new array reference

Author: zilinskyte

Sprint-1/implement/dedupe.test.js

@@ -27,6 +27,14 @@ test("given an array with no duplicates, it returns the same array", () => {
     expect(dedupe([1, 2, 3, 4, 5])).toEqual([1, 2, 3, 4, 5]);
 });
 
+// When passed an array
+// It should not return the same array reference
+test("It returns a new array, not the original", () => {
+    const original = [1, 2, 3];
+    const result = dedupe(original);
+    expect(result).not.toBe(original); // Check that the returned array is not the same reference as the original
+});
+
 // Given an array with strings or numbers
 // When passed to the dedupe function
 // Then it should remove the duplicate values, preserving the first occurrence of each element