Added a square class to the Geometry folder similar to the circle

Geometry/Circle.js

@@ -1,5 +1,5 @@
 /**
- * This class represents a circle and can calculate it's perimeter and area
+ * This class represents a circle and can calculate its perimeter and area
  * https://en.wikipedia.org/wiki/Circle
  * @constructor
  * @param {number} radius - The radius of the circle.

Geometry/Square.js

@@ -0,0 +1,19 @@
+/**
+ * This class represent a square and can calculate its perimeter and its area
+ * https://fr.wikipedia.org/wiki/Square
+ * @constructor
+ * @param {number} side - the length of a side of the square
+ */
+export default class Square {
+  constructor(side) {
+    this.side = side
+  }
+
+  perimeter = () => {
+    return 4 * this.side
+  }
+
+  area = () => {
+    return Math.pow(this.side, 2)
+  }
+}

Geometry/Test/Square.test.js

@@ -0,0 +1,13 @@
+import { expect } from 'vitest'
+import Square from '../Square'
+
+const square = new Square(4)
+
+// Using parseFloat() in case the side is a float
+test('The perimeter of a square with a side of length equal to 4', () => {
+  expect(parseFloat(square.perimeter().toFixed(2))).toEqual(16.0)
+})
+
+test('The area of a square with a side of length 4', () => {
+  expect(parseFloat(square.area().toFixed(2))).toEqual(16.0)
+})