You are building a data model for a financial application. Your task is to implement a validated descriptor that enforces type and range constraints on numeric attributes.

You are given the following class skeleton:

```python
class BoundedFloat:
    pass

class Position:
    quantity = BoundedFloat(min_value=0.0, max_value=10000.0)
    price = BoundedFloat(min_value=0.01, max_value=999999.99)

    def __init__(self, ticker, quantity, price):
        self.ticker = ticker
        self.quantity = quantity
        self.price = price
```

import unittest
import re

# Helper function to dynamically generate test names and assertions
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 TestUserCode(unittest.TestCase):

    def test_bounded_float_is_declared(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code, "BoundedFloat"),
            "The `BoundedFloat` class is declared.",
            "Expected `BoundedFloat` to be declared."
        )

    def test_bounded_float_has_get(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code.BoundedFloat, "__get__"),
            "The `BoundedFloat` descriptor defines `__get__`.",
            "Expected `BoundedFloat` to define `__get__`."
        )

    def test_bounded_float_has_set(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code.BoundedFloat, "__set__"),
            "The `BoundedFloat` descriptor defines `__set__`.",
            "Expected `BoundedFloat` to define `__set__`."
        )

    def test_bounded_float_has_set_name(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code.BoundedFloat, "__set_name__"),
            "The `BoundedFloat` descriptor defines `__set_name__`.",
            "Expected `BoundedFloat` to define `__set_name__`."
        )

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

    def test_qty_is_correct(self):
        import user_code
        try:
            condition = user_code.qty == 100.0
            failure_message = f"Expected `qty` to be `100.0`, but got `{user_code.qty}`."
        except AttributeError:
            condition = False
            failure_message = "The `qty` variable is not declared."
        _dynamic_test(
            self,
            condition,
            "The `qty` variable equals `100.0`.",
            failure_message
        )

    def test_prc_is_correct(self):
        import user_code
        try:
            condition = user_code.prc == 189.50
            failure_message = f"Expected `prc` to be `189.5`, but got `{user_code.prc}`."
        except AttributeError:
            condition = False
            failure_message = "The `prc` variable is not declared."
        _dynamic_test(
            self,
            condition,
            "The `prc` variable equals `189.5`.",
            failure_message
        )

    def test_type_error_raised(self):
        import user_code
        condition = False
        failure_message = "Expected `TypeError` when setting `quantity` to a non-numeric value."
        try:
            test_position = user_code.Position("MSFT", "not_a_number", 100.0)
        except TypeError:
            condition = True
        except Exception:
            failure_message = "Expected `TypeError`, but a different exception was raised."
        _dynamic_test(
            self,
            condition,
            "`BoundedFloat` raises `TypeError` when a non-numeric value is assigned.",
            failure_message
        )

    def test_value_error_raised(self):
        import user_code
        condition = False
        failure_message = "Expected `ValueError` when setting `quantity` below `min_value`."
        try:
            test_position = user_code.Position("MSFT", -1.0, 100.0)
        except ValueError:
            condition = True
        except Exception:
            failure_message = "Expected `ValueError`, but a different exception was raised."
        _dynamic_test(
            self,
            condition,
            "`BoundedFloat` raises `ValueError` when the value is outside the allowed range.",
            failure_message
        )

    def test_is_data_descriptor(self):
        import user_code
        _dynamic_test(
            self,
            hasattr(user_code.BoundedFloat, "__get__") and hasattr(user_code.BoundedFloat, "__set__"),
            "`BoundedFloat` is a data descriptor – it defines both `__get__` and `__set__`.",
            "Expected `BoundedFloat` to define both `__get__` and `__set__` to be a data descriptor."
        )


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

test_main.py

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Challenge: Your First Descriptor

Lösung