import unittest
import importlib
import re

def _dynamic_test(test_case, condition, success_message, failure_message):
    if condition:
        test_case._testMethodName = success_message
        test_case.assertTrue(True, success_message)
    else:
        test_case._testMethodName = failure_message
        test_case.fail(failure_message)

class TestDistanceConversion(unittest.TestCase):

    def test_distance_in_kilometers_is_declared(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code, 'distance_in_kilometers'),
            "The `distance_in_kilometers` variable is declared.",
            "Expected `distance_in_kilometers` variable to be declared."
        )

    def test_distance_in_kilometers_value_correct(self):
        import user_code
        expected_value = 4677.4
        actual_value = user_code.distance_in_kilometers
        _dynamic_test(
            self,
            actual_value == expected_value,
            f"The `distance_in_kilometers` variable contains `{expected_value}`.",
            f"Expected `distance_in_kilometers` to be `{expected_value}`, but got `{actual_value}`."
        )

    def test_distance_in_miles_is_declared(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code, 'distance_in_miles'),
            "The `distance_in_miles` variable is declared.",
            "Expected `distance_in_miles` variable to be declared."
        )

    def test_distance_in_miles_value_correct(self):
        import user_code
        expected_value = user_code.distance_in_kilometers / 1.609
        actual_value = user_code.distance_in_miles
        _dynamic_test(
            self,
            abs(actual_value - expected_value) < 0.01, 
            f"The `distance_in_miles` variable contains `{expected_value}`.",
            f"Expected `distance_in_miles` to be `{expected_value}`, but got `{actual_value}`."
        )

    def test_int_distance_in_miles_is_declared(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code, 'int_distance_in_miles'),
            "The `int_distance_in_miles` variable is declared.",
            "Expected `int_distance_in_miles` variable to be declared."
        )

    def test_int_distance_in_miles_value_correct(self):
        import user_code
        expected_value = int(user_code.distance_in_miles)
        actual_value = user_code.int_distance_in_miles
        _dynamic_test(
            self,
            actual_value == expected_value,
            f"The `int_distance_in_miles` variable contains `{expected_value}`.",
            f"Expected `int_distance_in_miles` to be `{expected_value}`, but got `{actual_value}`."
        )

    def test_int_distance_in_miles_is_integer(self):
        import user_code
        _dynamic_test(
            self,
            isinstance(user_code.int_distance_in_miles, int),
            "The `int_distance_in_miles` variable is of type `int`.",
            "Expected `int_distance_in_miles` to be of type `int`."
        )

    def test_division_operator_used(self):
        with open('user_code.py', 'r') as file:
            user_code_source = file.read()
        _dynamic_test(
            self,
            re.search(r'/', user_code_source),
            "The division `/` operator is used for conversion.",
            "Expected the division `/` operator to be used for conversion."
        )

    def test_int_function_used(self):
        with open('user_code.py', 'r') as file:
            user_code_source = file.read()
        _dynamic_test(
            self,
            re.search(r'int\s*\(', user_code_source),
            "The `int()` function is used to convert `distance_in_miles` to an integer.",
            "Expected the `int()` function to be used to convert `distance_in_miles` to an integer."
        )

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

With correct unit test

解答