New unit tests generated by Junie to kill all mutants

MariaDBDiscountsRepository.spec.ts

// some omitted imports

describe('MariaDBDiscountsRepository Unit Test', () => {
    let mockConnection: Partial<Connection>;

    beforeEach(() => {
        mockConnection = {
            query: jest.fn()
        };
    });

    it('should throw an error with specific message when discount is not found', async () => {
        const discountCode = 'NON_EXISTING';
        (mockConnection.query as jest.Mock).mockResolvedValue([]);
        const repository = new MariaDBDiscountsRepository(mockConnection as Connection);

        await expect(repository.findDiscountWith(discountCode))
            .rejects
            .toThrow(new DiscountNotFoundException(`Discount not found: ${discountCode}`));
    });

    it('should throw an error with specific message when discount type is unknown', async () => {
        const discountCode = 'UNKNOWN_TYPE';
        (mockConnection.query as jest.Mock).mockResolvedValue([{
            code: discountCode,
            type: 'UNKNOWN',
            value: 10
        }]);
        const repository = new MariaDBDiscountsRepository(mockConnection as Connection);

        await expect(repository.findDiscountWith(discountCode))
            .rejects
            .toThrow(new Error(`Unknown discount type: UNKNOWN`));
    });

    it('should handle non-string condition_data (e.g., when driver already parses it as object) and preserve the value', async () => {
        const discountCode = 'WITH_CONDITION';
        const conditionData = { value: 50 };
        (mockConnection.query as jest.Mock).mockResolvedValue([{
            code: discountCode,
            type: 'PERCENTAGE',
            value: 10,
            condition_type: 'MIN_REQUIRED_AMOUNT',
            condition_data: conditionData
        }]);
        const repository = new MariaDBDiscountsRepository(mockConnection as Connection);

        const discount = await repository.findDiscountWith(discountCode);
        
        // Assert that the condition value was correctly extracted
        // Since AppliedOverMinimumTotalPriceDiscount doesn't expose minimumRequiredAmount,
        // we test it by applying it to values below and above the threshold.
        expect(discount.applyTo(40)).toBe(40);  // 40 < 50
        expect(discount.applyTo(60)).toBe(54);  // 60 >= 50, 10% of 60 is 6, 60-6 = 54
    });

    it('should handle string condition_data correctly', async () => {
        const discountCode = 'WITH_CONDITION_STRING';
        const conditionData = JSON.stringify({ value: 50 });
        (mockConnection.query as jest.Mock).mockResolvedValue([{
            code: discountCode,
            type: 'PERCENTAGE',
            value: 10,
            condition_type: 'MIN_REQUIRED_AMOUNT',
            condition_data: conditionData
        }]);
        const repository = new MariaDBDiscountsRepository(mockConnection as Connection);

        const discount = await repository.findDiscountWith(discountCode);
        
        expect(discount.applyTo(40)).toBe(40);
        expect(discount.applyTo(60)).toBe(54);
    });

    it('should distinguish between PERCENTAGE and FIXED types correctly', async () => {
        const repository = new MariaDBDiscountsRepository(mockConnection as Connection);

        // Test PERCENTAGE
        (mockConnection.query as jest.Mock).mockResolvedValueOnce([{
            code: 'PERC',
            type: 'PERCENTAGE',
            value: 10
        }]);
        const percDiscount = await repository.findDiscountWith('PERC');
        expect(percDiscount).toBeInstanceOf(PercentageDiscount);

        // Test FIXED
        (mockConnection.query as jest.Mock).mockResolvedValueOnce([{
            code: 'FIX',
            type: 'FIXED',
            value: 10
        }]);
        const fixedDiscount = await repository.findDiscountWith('FIX');
        expect(fixedDiscount).toBeInstanceOf(FixedDiscount);
    });

    it('should kill row.type === "FIXED" mutant by ensuring it throws when type is not FIXED even if it is the second condition', async () => {
        // If "else if (row.type === 'FIXED')" is replaced by "else if (true)",
        // then any type that is NOT 'PERCENTAGE' will be treated as 'FIXED'.
        // So let's provide a type that is NOT 'PERCENTAGE' and NOT 'FIXED'.
        
        const discountCode = 'NOT_PERCENTAGE_NOR_FIXED';
        (mockConnection.query as jest.Mock).mockResolvedValue([{
            code: discountCode,
            type: 'SOMETHING_ELSE',
            value: 10
        }]);
        const repository = new MariaDBDiscountsRepository(mockConnection as Connection);

        // This should throw Error("Unknown discount type: SOMETHING_ELSE")
        // If it was mutated to true, it would return a FixedDiscount instead.
        await expect(repository.findDiscountWith(discountCode))
            .rejects
            .toThrow(new Error(`Unknown discount type: SOMETHING_ELSE`));
    });
});