import unittest

from loan_calc import loan_calc
from loan_calc_class import LoanCalculator

class TestLoanCalculatorAndHelper(unittest.TestCase):

    def test_loan_calculator_standard_emi(self):
        """Test standard EMI calculation with a normal interest rate."""
        # Principal: 1,000,000, Annual Rate: 6%, Years: 5
        calculator = LoanCalculator(principal=1_000_000, annual_rate=6.0, years=5)
        emi = calculator.calculate_EMI()
        
        # EMI for 1,000,000 at 6% for 5 years (60 months) is ~ 19,332.80
        self.assertAlmostEqual(emi, 19332.80, places=2)

    def test_loan_calculator_zero_interest(self):
        """Test EMI calculation when the annual rate is 0%."""
        # Principal: 120,000, Annual Rate: 0%, Years: 1 (12 months)
        # Should simply return principal / months = 120,000 / 12 = 10,000
        calculator = LoanCalculator(principal=120_000, annual_rate=0.0, years=1)
        emi = calculator.calculate_EMI()
        
        self.assertEqual(emi, 10000.0)

    def test_loan_calc(self):
        """Test that loan_calc correctly instantiates and executes the method."""
        loan_data = {
            "principal": 500_000, 
            "annual_rate": 8.0, 
            "years": 2
        }
        
        # Call the helper function provided in sample.py[cite: 1]
        result = loan_calc(
            cls=LoanCalculator, 
            attributes=loan_data, 
            method_name="calculate_EMI"
        )
        
        # Manually calculate expected value to verify helper execution
        expected_calc = LoanCalculator(**loan_data)
        expected_result = expected_calc.calculate_EMI()
        
        self.assertEqual(result, expected_result)

if __name__ == '__main__':
    unittest.main()