strings.test.js

const {
  sayHello,
  uppercase,
  lowercase,
  countCharacters,
  firstCharacter,
  firstCharacters
} = require('../strings');

describe('sayHello', () => {
  it('returns "Hello world!" when passed "world"', () => {
    expect(sayHello('world')).toEqual('Hello, world!');
  });

  it('returns "Hello MCR Codes!" when passed "MCR Codes"', () => {
    expect(sayHello('MCR Codes')).toEqual('Hello, MCR Codes!');
  });

  it('returns "Hello fsghjdfkhgf!" when passed "fsghjdfkhgf"', () => {
    expect(sayHello('fsghjdfkhgf')).toEqual('Hello, fsghjdfkhgf!');
  });
});

describe('uppercase', () => {
  it('returns the uppercased string', () => {
    expect(uppercase('abc')).toEqual('ABC');
    expect(uppercase('def')).toEqual('DEF');
    expect(uppercase('ghi')).toEqual('GHI');
  });
});

describe('lowercase', () => {
  it('returns the lowercased string', () => {
    expect(lowercase('ABC')).toEqual('abc');
    expect(lowercase('DEF')).toEqual('def');
    expect(lowercase('GHI')).toEqual('ghi');
  });
});

describe('countCharacters', () => {
  it('returns the number of characters in the string', () => {
    expect(countCharacters('fsfsgsfdg')).toEqual(9);
    expect(countCharacters('fsfsg')).toEqual(5);
    expect(countCharacters('')).toEqual(0);
  });
});

describe('firstCharacter', () => {
  it('returns the first character of the string', () => {
    expect(firstCharacter('ABC')).toEqual('A');
    expect(firstCharacter('DEF')).toEqual('D');
    expect(firstCharacter('GHI')).toEqual('G');
  });
});

describe('firstCharacters', () => {
  it('returns the first 4 characters of the string', () => {
    expect(firstCharacters('sd32fg45', 4)).toEqual('sd32');
  });

  it('returns the first 2 characters of the string', () => {
    expect(firstCharacters('asd', 2)).toEqual('as');
  });
});