var calculator;
before(function() {
  calculator = new Calculator;
});

it("calculate(12 + 34) = 46", function() {
  assert.equal(calculator.calculate("12 + 34"), 46);
});

it("calculate(34 - 12) = 22", function() {
  assert.equal(calculator.calculate("34 - 12"), 22);
});

it("добавили умножение: calculate(2 * 3) = 6", function() {
  calculator.addMethod("*", function(a, b) {
    return a * b;
  });
  assert.equal(calculator.calculate("2 * 3"), 6);
});

it("добавили возведение в степень: calculate(2 ** 3) = 8", function() {
  calculator.addMethod("**", function(a, b) {
    return Math.pow(a, b);
  });
  assert.equal(calculator.calculate("2 ** 3"), 8);
});