Added new algoritm

String/MaxCharacter.test.js

@@ -0,0 +1,12 @@
+import { maxCharacter } from './MaxCharacter'
+
+describe('Testing the maxCharacter function', () => {
+  it('Expect throw with wrong arg', () => {
+    expect(() => maxCharacter(123)).toThrow()
+  })
+  it('Check the max character in string', () => {
+    const theString = 'I can\'t do that'
+    const maxChar = maxCharacter(theString)
+    expect(maxChar).toBe('t')
+  })
+})