6.String Builder-unit

describe('Test StringBuilder class', () => {
  it('Has initial param', () => {
    expect(StringBuilder.prototype.hasOwnProperty('append')).to.be.equal(true);
    expect(StringBuilder.prototype.hasOwnProperty('prepend')).to.be.equal(true);
    expect(StringBuilder.prototype.hasOwnProperty('insertAt')).to.be.equal(true);
    expect(StringBuilder.prototype.hasOwnProperty('remove')).to.be.equal(true);
    expect(StringBuilder.prototype.hasOwnProperty('toString')).to.be.equal(true);
  });

  it('If param is undefined should return obj with empty arr', () => {
    const str = new StringBuilder();
    expect(str._stringArray.length).to.be.equal(0);
  });

  it('_stringArray must be array ', () => {
    const str = new StringBuilder();
    expect(Array.isArray(str._stringArray)).to.be.equal(true);
  });

  it('Should return not empty arr if passed param is not undefined', () => {
    const str = new StringBuilder('test');
    expect(str._stringArray.length).to.be.equal(4);
  });

  it('Should throw error if param is not string type', () => {
    const str = new StringBuilder();
    const willThrow = () => str.append(5);
    expect(willThrow).to.throw();
  });

  it('Test append function', () => {
    const str = new StringBuilder('str');
    str.append('newStr');
    expect(str._stringArray.join('')).to.be.equal('strnewStr');
  });

  it('Test prepend function', () => {
    const str = new StringBuilder('str');
    str.prepend('newStr');
    expect(str._stringArray.join('')).to.be.equal('newStrstr');
  });

  it('Test insertAt function', () => {
    const str = new StringBuilder('s');
    str.insertAt('st', 0);
    expect(str._stringArray.join('')).to.be.equal('sts');
    expect(str._stringArray.length).to.be.equal(3);
  });

  it('Test remove function', () => {
    const str = new StringBuilder('str');
    str.remove(0, 2);
    expect(str._stringArray.join('')).to.be.equal('r');
  });

  it('Test toString function', () => {
    const str = new StringBuilder('str');
    str.append('newStr');
    str.remove(0, 1);
    str.append('testnewstr');
    expect(str.toString()).to.be.equal('trnewStrtestnewstr');
  });
});