diff --git a/starter-code/tests/FunctionsAndArraysSpec.js b/starter-code/tests/FunctionsAndArraysSpec.js
index 33205fcf7..e57cc3487 100644
--- a/starter-code/tests/FunctionsAndArraysSpec.js
+++ b/starter-code/tests/FunctionsAndArraysSpec.js
@@ -1,6 +1,5 @@
-/* eslint no-undef: 'off' */
 function shuffle(currentArray) {
-  var array = currentArray.map(function (arr) {
+  var array = currentArray.map(function(arr) {
     return arr.slice();
   });
   var counter = array.length;
@@ -13,185 +12,239 @@ function shuffle(currentArray) {
   }
   return array;
 }
-describe('Find the maximum - maxOfTwoNumbers', function () {
-  it('Defines maxOfTwoNumbers', function () {
-    expect(typeof maxOfTwoNumbers).toBe('function');
+describe("Find the maximum - maxOfTwoNumbers", function() {
+  it("Defines maxOfTwoNumbers", function() {
+    expect(typeof maxOfTwoNumbers).toBe("function");
   });
 
-  it('First parameter larger', function () {
+  it("First parameter larger", function() {
     expect(maxOfTwoNumbers(2, 1)).toBe(2);
   });
 
-  it('Second parameter larger', function () {
+  it("Second parameter larger", function() {
     expect(maxOfTwoNumbers(1, 3)).toBe(3);
   });
 
-  it('First and Second parameter equal', function () {
+  it("First and Second parameter equal", function() {
     expect(maxOfTwoNumbers(4, 4)).toBe(4);
   });
 });
 
-describe('Finding Longest Word - findLongestWord', function () {
-  it('Defines findLongestWord', function () {
-    expect(typeof findLongestWord).toBe('function');
+describe("Finding Longest Word - findLongestWord", function() {
+  it("Defines findLongestWord", function() {
+    expect(typeof findLongestWord).toBe("function");
   });
 
-  it('returns undefined with an empty array', function () {
-    expect(findLongestWord([])).toBe(undefined);
+  it("returns null with an empty array", function() {
+    expect(findLongestWord([])).toBe(null);
   });
 
-  it('returns the word with an 1-word array', function () {
-    expect(findLongestWord(['foo'])).toBe('foo');
+  it("returns the word with an 1-word array", function() {
+    expect(findLongestWord(["foo"])).toBe("foo");
   });
 
-  it('returns the first occurrence word when longest have multiple occurrences ', function () {
-    expect(findLongestWord(['foo', 'bar'])).toBe('foo');
-    expect(findLongestWord(['bar', 'foo'])).toBe('bar');
+  it("returns the first occurrence word when longest have multiple occurrences ", function() {
+    expect(findLongestWord(["foo", "bar"])).toBe("foo");
+    expect(findLongestWord(["bar", "foo"])).toBe("bar");
   });
 
-  it('returns the longest occurrence when it has multiple words', function () {
-    var words = ['a', 'zab', '12abc', '$$abcd', 'abcde', 'ironhack'];
+  it("returns the longest occurrence when it has multiple words", function() {
+    var words = ["a", "zab", "12abc", "$$abcd", "abcde", "ironhack"];
     for (var i = 0; i < 10; i++) {
       words = shuffle(words);
-      expect(findLongestWord(words)).toBe('ironhack');
+      expect(findLongestWord(words)).toBe("ironhack");
     }
   });
 });
 
-describe('Calculating a Sum - sumArray', function () {
-  it('Defines sumArray', function () {
-    expect(typeof sumArray).toBe('function');
+describe("Calculating a Sum - sumArray", function() {
+  it("Defines sumArray", function() {
+    expect(typeof sumArray).toBe("function");
   });
 
-  it('returns zero with an empty array', function () {
+  it("returns zero with an empty array", function() {
     expect(sumArray([])).toBe(0);
   });
 
-  it('returns the sum with one number array', function () {
+  it("returns the sum with one number array", function() {
     expect(sumArray([4])).toBe(4);
   });
 
-  it('returns zero if all elements are zero', function () {
+  it("returns zero if all elements are zero", function() {
     expect(sumArray([0, 0, 0, 0, 0])).toBe(0);
   });
 
-  it('returns the sum', function () {
+  it("returns the sum", function() {
     expect(sumArray([10, 5, 4, 32, 8])).toBe(59);
   });
 });
 
-describe('Calculating the Average - averageNumbers', function () {
-  it('Defines averageNumbers', function () {
-    expect(typeof averageNumbers).toBe('function');
+describe("Calculating the Average - averageNumbers", function() {
+  it("Defines averageNumbers", function() {
+    expect(typeof averageNumbers).toBe("function");
   });
 
-  it('returns undefined with an empty array', function () {
-    expect(averageNumbers([])).toBe(undefined);
+  it("returns null with an empty array", function() {
+    expect(averageNumbers([])).toBe(null);
   });
 
-  it('returns the average of a unique element array', function () {
+  it("returns the average of a unique element array", function() {
     expect(averageNumbers([9])).toBe(9);
   });
 
-  it('returns the average even with negative values', function () {
+  it("returns the average even with negative values", function() {
     expect(averageNumbers([9, -3, -4, 6])).toBe(2);
   });
 
-  it('returns the average of the array', function () {
+  it("returns the average of the array", function() {
     expect(averageNumbers([9, 10, 82, 92, 32, 102, 58])).toBe(55);
   });
 });
 
-describe('Calculating the Average - averageWordLength', function () {
-  it('Defines averageWordLength', function () {
-    expect(typeof averageWordLength).toBe('function');
+describe("Calculating the Average - averageWordLength", function() {
+  it("Defines averageWordLength", function() {
+    expect(typeof averageWordLength).toBe("function");
   });
 
-  it('returns undefined with an empty array', function () {
-    expect(averageWordLength([])).toBe(undefined);
+  it("returns null with an empty array", function() {
+    expect(averageWordLength([])).toBe(null);
   });
 
-  it('returns the average of a unique element array', function () {
-    expect(averageWordLength(['ironhack'])).toBe(8);
+  it("returns the average of a unique element array", function() {
+    expect(averageWordLength(["ironhack"])).toBe(8);
   });
 
-  it('returns the average of a the array', function () {
-    expect(averageWordLength(['Ironhack', 'Madrid', 'Barcelona', 'Paris', 'Miami', 'Mexico', 'Berlin', 'Programmers'])).toBe(7);
+  it("returns the average of a the array", function() {
+    expect(
+      averageWordLength([
+        "Ironhack",
+        "Madrid",
+        "Barcelona",
+        "Paris",
+        "Miami",
+        "Mexico",
+        "Berlin",
+        "Programmers"
+      ])
+    ).toBe(7);
   });
 });
 
-describe('Unique Arrays - uniquifyArray', function () {
-  it('Defines uniquifyArray', function () {
-    expect(typeof uniquifyArray).toBe('function');
+describe("Unique Arrays - uniquifyArray", function() {
+  it("Defines uniquifyArray", function() {
+    expect(typeof uniquifyArray).toBe("function");
   });
 
-  it('returns undefined with an empty array', function () {
-    expect(uniquifyArray([])).toBe(undefined);
+  it("returns [] with an empty array", function() {
+    expect(uniquifyArray([])).toEqual([]);
   });
 
-  it('returns the correct array when having an array of the same element', function () {
-    expect(uniquifyArray(['Ironhack', 'Ironhack', 'Ironhack'])).toEqual(['Ironhack']);
+  it("returns the correct array when having an array of the same element", function() {
+    expect(uniquifyArray(["Ironhack", "Ironhack", "Ironhack"])).toEqual([
+      "Ironhack"
+    ]);
   });
 
-  it('returns the same array when no element is repeated', function () {
-    expect(uniquifyArray(['Cat', 'Dog', 'Cow'])).toEqual(['Cat', 'Dog', 'Cow']);
+  it("returns the same array when no element is repeated", function() {
+    expect(uniquifyArray(["Cat", "Dog", "Cow"])).toEqual(["Cat", "Dog", "Cow"]);
   });
 
-  it('returns the uniquified array', function () {
-    expect(uniquifyArray(['iPhone', 'Samsung', 'Android', 'iOS', 'iPhone', 'Samsung', 'Nokia', 'Blackberry', 'Android'])).toEqual(['iPhone', 'Samsung', 'Android', 'iOS', 'Nokia', 'Blackberry']);
+  it("returns the uniquified array", function() {
+    expect(
+      uniquifyArray([
+        "iPhone",
+        "Samsung",
+        "Android",
+        "iOS",
+        "iPhone",
+        "Samsung",
+        "Nokia",
+        "Blackberry",
+        "Android"
+      ])
+    ).toEqual(["iPhone", "Samsung", "Android", "iOS", "Nokia", "Blackberry"]);
   });
 });
 
-describe('Finding Elements - doesWordExist', function () {
-  it('Defines doesWordExist', function () {
-    expect(typeof doesWordExist).toBe('function');
+describe("Finding Elements - doesWordExist", function() {
+  it("Defines doesWordExist", function() {
+    expect(typeof doesWordExist).toBe("function");
   });
 
-  it('returns false with an empty array', function () {
+  it("returns false with an empty array", function() {
     expect(doesWordExist([])).toBe(false);
   });
 
-  it('returns true if the word we are looking is the only one on the array', function () {
-    expect(doesWordExist(['machine'], 'machine')).toBe(true);
+  it("returns true if the word we are looking is the only one on the array", function() {
+    expect(doesWordExist(["machine"], "machine")).toBe(true);
   });
 
-  it('returns false if the word we are looking is not in the array', function () {
-    expect(doesWordExist(['machine', 'poison', 'eat', 'apple', 'horse'], 'ratatouille')).toBe(false);
+  it("returns false if the word we are looking is not in the array", function() {
+    expect(
+      doesWordExist(
+        ["machine", "poison", "eat", "apple", "horse"],
+        "ratatouille"
+      )
+    ).toBe(false);
   });
 
-  it('returns true if the word we are looking is in the array', function () {
-    expect(doesWordExist(['pizza', 'sandwich', 'snack', 'soda', 'book', 'computer'], 'book')).toBe(true);
+  it("returns true if the word we are looking is in the array", function() {
+    expect(
+      doesWordExist(
+        ["pizza", "sandwich", "snack", "soda", "book", "computer"],
+        "book"
+      )
+    ).toBe(true);
   });
 });
 
-describe('Counting Repetition - howManyTimes', function () {
-  it('Defines howManyTimes', function () {
-    expect(typeof howManyTimes).toBe('function');
+describe("Counting Repetition - howManyTimes", function() {
+  it("Defines howManyTimes", function() {
+    expect(typeof howManyTimes).toBe("function");
   });
 
-  it('returns false with an empty array', function () {
-    expect(howManyTimes([])).toBe(false);
+  it("returns 0 with an empty array", function() {
+    expect(howManyTimes([])).toBe(0);
   });
 
-  it('returns one when the word appears only one time on the array', function () {
-    expect(howManyTimes(['basketball', 'football', 'tennis'], 'tennis')).toBe(1);
+  it("returns one when the word appears only one time on the array", function() {
+    expect(howManyTimes(["basketball", "football", "tennis"], "tennis")).toBe(
+      1
+    );
   });
 
-  it('returns zero when the word does not appears on the array', function () {
-    expect(howManyTimes(['basketball', 'football', 'tennis'], 'rugby')).toBe(0);
+  it("returns zero when the word does not appears on the array", function() {
+    expect(howManyTimes(["basketball", "football", "tennis"], "rugby")).toBe(0);
   });
 
-  it('returns five when the word appears 5 times on the array', function () {
-    expect(howManyTimes(['basketball', 'football', 'tennis', 'rugby', 'rugby', 'ping pong', 'rugby', 'basketball', 'rugby', 'handball', 'rugby'], 'rugby')).toBe(5);
+  it("returns five when the word appears 5 times on the array", function() {
+    expect(
+      howManyTimes(
+        [
+          "basketball",
+          "football",
+          "tennis",
+          "rugby",
+          "rugby",
+          "ping pong",
+          "rugby",
+          "basketball",
+          "rugby",
+          "handball",
+          "rugby"
+        ],
+        "rugby"
+      )
+    ).toBe(5);
   });
 });
 
-describe('Bonus Quest - greatestProduct', function () {
-  it('Defines greatestProduct', function () {
-    expect(typeof greatestProduct).toBe('function');
+describe("Bonus Quest - greatestProduct", function() {
+  it("Defines greatestProduct", function() {
+    expect(typeof greatestProduct).toBe("function");
   });
 
-  it('Return 1 when all the numbers of the arrays are 1', function () {
+  it("Return 1 when all the numbers of the arrays are 1", function() {
     var matrix = [
       [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
       [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1],
@@ -217,7 +270,7 @@ describe('Bonus Quest - greatestProduct', function () {
     expect(greatestProduct(matrix)).toBe(1);
   });
 
-  it('Return 16 when all the numbers of the arrays are 2', function () {
+  it("Return 16 when all the numbers of the arrays are 2", function() {
     var matrix = [
       [2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2],
       [2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2],
@@ -243,4 +296,3 @@ describe('Bonus Quest - greatestProduct', function () {
     expect(greatestProduct(matrix)).toBe(16);
   });
 });
-