diff --git a/Geometry/Circle.js b/Geometry/Circle.js
index 3e3a3e03f4..914cd264b8 100644
--- a/Geometry/Circle.js
+++ b/Geometry/Circle.js
@@ -6,14 +6,37 @@
  */
 export default class Circle {
   constructor(radius) {
+    if (radius <= 0) {
+      throw new RangeError('Radius should be a positive number')
+    }
     this.radius = radius
   }
-
+  // Formular to Calculate the perimeter of a circle
   perimeter = () => {
     return this.radius * 2 * Math.PI
   }
 
+  // Formular to Calculate the area of a circle
   area = () => {
     return Math.pow(this.radius, 2) * Math.PI
   }
+
+  // Formular to Calculate the diameter of a circle
+  diameter = () => {
+    return 2 * this.radius
+  }
+  // Function That Changes the value of the default radius
+  changeRadius = (newRadius) => {
+    if (newRadius <= 0) {
+      throw new RangeError('New radius should be a positive number')
+    }
+    this.radius = newRadius
+  }
+  // Function That Calculates the length of an arc
+  lengthOfArc = (angle) => {
+    if (angle <= 0) {
+      throw new RangeError('Angle should be a positive number')
+    }
+    return this.radius * angle
+  }
 }
diff --git a/Geometry/Test/Circle.test.js b/Geometry/Test/Circle.test.js
index b2332df43d..ecd4da4ec4 100644
--- a/Geometry/Test/Circle.test.js
+++ b/Geometry/Test/Circle.test.js
@@ -2,6 +2,10 @@ import Circle from '../Circle'
 
 const circle = new Circle(3)
 
+test('The radius of the circle should be initialized to 3', () => {
+  expect(circle.radius).toEqual(3)
+})
+
 test('The area of a circle with radius equal to 3', () => {
   expect(parseFloat(circle.area().toFixed(2))).toEqual(28.27)
 })
@@ -9,3 +13,17 @@ test('The area of a circle with radius equal to 3', () => {
 test('The perimeter of a circle with radius equal to 3', () => {
   expect(parseFloat(circle.perimeter().toFixed(2))).toEqual(18.85)
 })
+
+test('The diameter of a circle with radius equal to 3', () => {
+  expect(parseFloat(circle.diameter().toFixed(2))).toEqual(6.0)
+})
+
+test('Change radius and check if it reflects in calculations', () => {
+  circle.changeRadius(4)
+  expect(circle.radius).toEqual(4)
+  expect(parseFloat(circle.area().toFixed(2))).toEqual(50.27)
+})
+
+test('The Length of arc in radian of the circle', () => {
+  expect(parseFloat(circle.lengthOfArc(2.1).toFixed(2))).toEqual(8.4)
+})
diff --git a/Recursive/Factorial.js b/Recursive/Factorial.js
index 5a0d560514..4e2b3c1bff 100644
--- a/Recursive/Factorial.js
+++ b/Recursive/Factorial.js
@@ -9,17 +9,14 @@
  */
 
 const factorial = (n) => {
-  if (!Number.isInteger(n)) {
-    throw new RangeError('Not a Whole Number')
-  }
-
-  if (n < 0) {
-    throw new RangeError('Not a Positive Number')
+  if (!Number.isInteger(n) || n < 0) {
+    throw new RangeError('Input should be a non-negative whole number')
   }
 
   if (n === 0) {
     return 1
   }
+
   return n * factorial(n - 1)
 }
 
diff --git a/Recursive/test/Factorial.test.js b/Recursive/test/Factorial.test.js
index 5f32a44332..e89be9831e 100644
--- a/Recursive/test/Factorial.test.js
+++ b/Recursive/test/Factorial.test.js
@@ -10,10 +10,20 @@ describe('Factorial', () => {
   })
 
   it('Throw Error for Invalid Input', () => {
-    expect(() => factorial('-')).toThrow('Not a Whole Number')
-    expect(() => factorial(null)).toThrow('Not a Whole Number')
-    expect(() => factorial(undefined)).toThrow('Not a Whole Number')
-    expect(() => factorial(3.142)).toThrow('Not a Whole Number')
-    expect(() => factorial(-1)).toThrow('Not a Positive Number')
+    expect(() => factorial('-')).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(null)).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(undefined)).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(3.142)).toThrow(
+      'Input should be a non-negative whole number'
+    )
+    expect(() => factorial(-1)).toThrow(
+      'Input should be a non-negative whole number'
+    )
   })
 })