Implement dedupe function

Author: cyf

Sprint-1/implement/dedupe.js

@@ -1 +1,5 @@
-function dedupe() {}
+function dedupe(arr) {
+  return [...new Set(arr)];
+}
+
+module.exports = dedupe;

Sprint-1/implement/dedupe.test.js

@@ -1,4 +1,3 @@
-const dedupe = require("./dedupe.js");
 /*
 Dedupe Array
 
@@ -16,13 +15,41 @@ E.g. dedupe([1, 2, 1]) returns [1, 2]
 // Given an empty array
 // When passed to the dedupe function
 // Then it should return an empty array
-test.todo("given an empty array, it returns an empty array");
+//test.todo("given an empty array, it returns an empty array");
+
+const dedupe = require("./dedupe");
+
+// Given an empty array
+// When passed to the dedupe function
+// Then it should return an empty array
+test("should return an empty array when given an empty array", () => {
+  expect(dedupe([])).toEqual([]);
+});
 
 // Given an array with no duplicates
 // When passed to the dedupe function
 // Then it should return a copy of the original array
+test("should return a copy of the original array when there are no duplicates", () => {
+  expect(dedupe([1, 2, 3, 4])).toEqual([1, 2, 3, 4]);
+});
+
+// Given an array of strings with duplicates
+// When passed to the dedupe function
+// Then it should remove duplicate strings while preserving the first occurrence
+test("should remove duplicate strings while preserving the first occurrence", () => {
+  expect(dedupe(["a", "a", "a", "b", "b", "c"])).toEqual(["a", "b", "c"]);
+});
+
+// Given an array of numbers with duplicates
+// When passed to the dedupe function
+// Then it should remove duplicate numbers while preserving the first occurrence
+test("should remove duplicate numbers while preserving the first occurrence", () => {
+  expect(dedupe([5, 1, 1, 2, 3, 2, 5, 8])).toEqual([5, 1, 2, 3, 8]);
+});
 
-// Given an array of strings or numbers
+// Given an array with one element
 // When passed to the dedupe function
-// Then it should return a new array with duplicates removed while preserving the 
-// first occurrence of each element from the original array.
+// Then it should return the same array
+test("should return the same array when it contains only one element", () => {
+  expect(dedupe([42])).toEqual([42]);
+});