Add Email Validation Function (#462)

* Add Email Validation Function

* fix standard styling issues

String/ValidateEmail.js

@@ -0,0 +1,19 @@
+/*
+  function that takes a string input and return either it is true of false
+  a valid email address
+  e.g.: mahfoudh.arous@gmail.com -> true
+  e.g.: mahfoudh.arous.com ->false
+*/
+
+const validateEmail = (str) => {
+  if (str === '' || str === null) {
+    throw new TypeError('Email Address String Null or Empty.')
+  }
+  if (str.startsWith('@') === true || !str.includes('@') || !str.endsWith('.com')) {
+    return false
+  }
+
+  return true
+}
+
+export { validateEmail }

String/ValidateEmail.test.js

@@ -0,0 +1,19 @@
+import { validateEmail } from './ValidateEmail'
+
+describe('Validation of an Email Address', () => {
+  it('expects to return false', () => {
+    expect(validateEmail('mahfoudh.arous.com')).toEqual(false)
+  })
+
+  it('expects to return false', () => {
+    expect(validateEmail('mahfoudh.arous@com')).toEqual(false)
+  })
+
+  it('expects to return true', () => {
+    expect(validateEmail('mahfoudh.arous@gmail.com')).toEqual(true)
+  })
+
+  it('expects to throw a type error', () => {
+    expect(() => { validateEmail('') }).toThrow('Email Address String Null or Empty.')
+  })
+})