Add tests to Math (#423)

* Add prettier config

* test: add test to check for absolute function

* chore: es5 to es6

* test: add test to check mean function

* test: add test for sum of digit

* test: add test for factorial

* test: add test for fibonnaci

* test: add test for find HCF

* test: add test for lcm

* test: add gridget test

* test: add test for mean square error

* test: add test for modular binary exponentiation

* test: add tests for palindrome

* test: add test for pascals triangle

* test: add tests for polynomial

* test: add tests for prime check

* test: add tests for reverse polish notation

* test: add tests for sieve of eratosthenes

* test: add tests for pi estimation monte carlo method

* chore: move tests to test folder

* chore: fix standardjs errors

Maths/test/MeanSquareError.test.js

@@ -0,0 +1,21 @@
+import { meanSquaredError } from '../MeanSquareError'
+
+describe('meanSquareError', () => {
+  it('should throw an error on non-array arguments', () => {
+    expect(() => meanSquaredError(1, 4)).toThrow('Argument must be an Array')
+  })
+
+  it('should throw an error on non equal length ', () => {
+    const firstArr = [1, 2, 3, 4, 5]
+    const secondArr = [1, 2, 3]
+    expect(() => meanSquaredError(firstArr, secondArr)).toThrow(
+      'The two lists must be of equal length'
+    )
+  })
+
+  it('should return the mean square error of two equal length arrays', () => {
+    const firstArr = [1, 2, 3, 4, 5]
+    const secondArr = [1, 3, 5, 6, 7]
+    expect(meanSquaredError(firstArr, secondArr)).toBe(2.6)
+  })
+})