diff --git a/DIRECTORY.md b/DIRECTORY.md
index 4f1c033352..2d70c5d6a2 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -9,10 +9,12 @@
   * [SumOfSubset](Backtracking/SumOfSubset.js)
 * **Bit-Manipulation**
   * [BinaryCountSetBits](Bit-Manipulation/BinaryCountSetBits.js)
+  * [IsPowerofFour](Bit-Manipulation/IsPowerofFour.js)
   * [IsPowerOfTwo](Bit-Manipulation/IsPowerOfTwo.js)
   * [LogTwo](Bit-Manipulation/LogTwo.js)
   * [NextPowerOfTwo](Bit-Manipulation/NextPowerOfTwo.js)
   * [SetBit](Bit-Manipulation/SetBit.js)
+  * [UniqueElementInAnArray](Bit-Manipulation/UniqueElementInAnArray.js)
 * **Cache**
   * [LFUCache](Cache/LFUCache.js)
   * [LRUCache](Cache/LRUCache.js)
@@ -270,6 +272,7 @@
   * [Problem017](Project-Euler/Problem017.js)
   * [Problem018](Project-Euler/Problem018.js)
   * [Problem020](Project-Euler/Problem020.js)
+  * [Problem021](Project-Euler/Problem021.js)
   * [Problem023](Project-Euler/Problem023.js)
   * [Problem025](Project-Euler/Problem025.js)
   * [Problem028](Project-Euler/Problem028.js)
diff --git a/Maths/test/ParityOutlier.test.js b/Maths/test/ParityOutlier.test.js
index ed3307dcd0..73b9159dc0 100644
--- a/Maths/test/ParityOutlier.test.js
+++ b/Maths/test/ParityOutlier.test.js
@@ -9,17 +9,14 @@ describe('Testing parityOutlier function', () => {
     expect(parityOutlier([177, 5, 76, 1919])).toBe(76)
   })
 
-  it('should, if the given array has only one integer element, return the integer itself', () => {
-    expect(parityOutlier([83])).toBe(83)
-    expect(parityOutlier([54])).toBe(54)
-  })
-
   it('should, if the given array has only an odd and an even number, return the odd outlier', () => {
     expect(parityOutlier([1, 2])).toBe(1)
     expect(parityOutlier([4, 3])).toBe(3)
   })
 
   it('should return null if the given array is empty, contains only one integer, contains non-interger elements or does not have a parity outlier', () => {
+    expect(parityOutlier([83])).toBe(null)
+    expect(parityOutlier([54])).toBe(null)
     expect(parityOutlier([])).toBe(null)
     expect(parityOutlier([2])).toBe(null)
     expect(parityOutlier([2, {}, 5, 'GitHub'])).toBe(null)
diff --git a/String/test/ValidateUrl.test.js b/String/test/ValidateUrl.test.js
deleted file mode 100644
index e19e46e0f5..0000000000
--- a/String/test/ValidateUrl.test.js
+++ /dev/null
@@ -1,14 +0,0 @@
-import { validateURL } from '../ValidateUrl'
-
-describe('ValidateUrl', () => {
-  it('expects to return false', () => {
-    expect(validateURL('google')).toEqual(false)
-    expect(validateURL('link: https://www.google.com')).toEqual(false)
-  })
-
-  it('expects to return true', () => {
-    expect(validateURL('http://www.google.com')).toEqual(true)
-    expect(validateURL('https://www.google.com')).toEqual(true)
-    expect(validateURL('www.google.com')).toEqual(true)
-  })
-})