Strengthen dedupe test by adding length and content checks to prevent false positives

Author: Pretty Taruvinga

Sprint-1/implement/dedupe.test.js

@@ -38,6 +38,7 @@ test("Given an array with no duplicates, when passed to the dedupe function, the
 
   expect(result).toEqual(input);
   expect(result).not.toBe(input);
+  expect(result.length).toBe(input.length);
 });
 
 // Given an array of strings or numbers