index.test.ts

import { simpleCalculator, Action } from './index';

describe('simpleCalculator tests', () => {
  test('should add two numbers', () => {
    expect(simpleCalculator({a: 1, b: 2, action: Action.Add})).toBe(3);
  });

  //определяет один тест,
  //функция Jest, создаёт утверждение (assertion), которое проверяет результат
  //сравнивает строго (===) возвращаемое значение с ожидаемым.

  test('should subtract two numbers', () => {
    expect(simpleCalculator({a:1, b:2, action: Action.Subtract})).toBe(-1);
  });

  test('should multiply two numbers', () => {
    expect(simpleCalculator({a:3, b:2, action: Action.Multiply})).toBe(6);
  });

  test('should divide two numbers', () => {
    expect(simpleCalculator({a:3, b:2, action: Action.Divide})).toBe(1.5);
  });

  test('should exponentiate two numbers', () => {
    expect(simpleCalculator({a:3, b:2, action: Action.Exponentiate})).toBe(9);
  });

  test('should return null for invalid action', () => {
    expect(simpleCalculator({a:3, b:0, action: 'InvalidAction'})).toBeNull();
  });

  test('should return null for invalid arguments', () => {
    expect(simpleCalculator({a:"3", b:1, action: Action.Add})).toBeNull();
  });
});