const Calculator = require('../../src/calculator');

describe('Calculator', () => {
    let calculator;

    beforeEach(() => {
        calculator = new Calculator();
    });

    test('should add two numbers correctly', () => {
        expect(calculator.add(2, 3)).toBe(5);
        expect(calculator.add(-1, 1)).toBe(0);
        expect(calculator.add(0, 0)).toBe(0);
    });

    test('should subtract two numbers correctly', () => {
        expect(calculator.subtract(5, 3)).toBe(2);
        expect(calculator.subtract(1, 1)).toBe(0);
        expect(calculator.subtract(0, 5)).toBe(-5);
    });

    test('should multiply two numbers correctly', () => {
        expect(calculator.multiply(3, 4)).toBe(12);
        expect(calculator.multiply(-2, 3)).toBe(-6);
        expect(calculator.multiply(0, 5)).toBe(0);
    });

    test('should divide two numbers correctly', () => {
        expect(calculator.divide(10, 2)).toBe(5);
        expect(calculator.divide(7, 2)).toBe(3.5);
        expect(calculator.divide(-6, 3)).toBe(-2);
    });

    test('should throw error when dividing by zero', () => {
        expect(() => calculator.divide(5, 0)).toThrow('Division by zero is not allowed');
    });

    test('should maintain calculation history', () => {
        calculator.add(2, 3);
        calculator.multiply(4, 5);
        
        const history = calculator.getHistory();
        expect(history).toHaveLength(2);
        expect(history[0]).toBe('2 + 3 = 5');
        expect(history[1]).toBe('4 * 5 = 20');
    });

    test('should clear history', () => {
        calculator.add(1, 1);
        calculator.clearHistory();
        expect(calculator.getHistory()).toHaveLength(0);
    });
});