04. Sum of Numbers

describe('sum(arr) - sum array of numbers', () => {
  it('should return 3 for [1,2]', () => {
    expect(sum([1, 2])).to.be.equal(3);
  });
  it('should return 1 for [1]', () => {
    expect(sum([1])).to.be.equal(1);
  });
  it('should return 0 for empty array', () => {
    expect(sum([])).to.be.equal(0);
  });
  it('should return 3 for [1.5, 2.5, -1]', () => {
    expect(sum([1.5, 2.5, -1])).to.be.equal(3);
  });
  it('should return NaN for invalid data', () => {
    expect(sum('invalid data')).to.be.NaN;
  });
});