Class Prophecy

src/bonsai/test/core/bootstrap.py:286–401

Rough outline how it works: 1. Test run pass: - Remember calls (all calls should also have ``.should_be_called()`` after). - Remember predictions. - Associate return values with calls. 2. Core function pass: - Remember calls. - Use return values from the first pass.

class Prophecy:
    """
    Rough outline how it works:
    1. Test run pass:
    - Remember calls (all calls should also have ``.should_be_called()`` after).
    - Remember predictions.
    - Associate return values with calls.

    2. Core function pass:
    - Remember calls.
    - Use return values from the first pass.

    3. Verification pass:
    - Ensure all predicted calls actually happened.
    """

    subject: type

    def __init__(self, cls: type):
        self.subject = cls
        self.predictions: list[Prediction] = []
        self.calls: list[Call] = []
        self.return_values: dict[str, Any] = {}
        self.should_call: Optional[Call] = None

    @staticmethod
    def serialize(call: Call) -> str:
        return json.dumps(call, sort_keys=True)

    def __repr__(self) -> str:
        return f"<Prophecy for '{self.subject.__original_qualname__}'>"

    def __getattr__(self, attr: str):
        if not hasattr(self.subject, attr):
            raise AttributeError(f"Interface '{self.subject.__original_qualname__}' has no attribute '{attr}'.")

        # It also returns `Any` but it only happens during `subject.xxx` call.
        def decorate(*args: Any, **kwargs: Any) -> Self:
            """Remember a call."""
            call: Call = {"name": attr, "args": args, "kwargs": kwargs}
            # Ensure that signature is valid
            getattr(self.subject, attr)(*args, **kwargs)

            try:
                key = self.serialize(call)
            except TypeError as e:
                # Serialization error will occur if unpredicted return value
                # will be used as an argument to other call
                msg = f"Failed to serialize call: '{call}'."
                values = list(flatten(args)) + list(flatten(kwargs.values()))
                prophecy = next((value for value in values if isinstance(value, Prophecy)), None)
                if prophecy is None:
                    msg += "\nCouldn't find related Prophecy."
                    raise TypeError(msg) from e

                msg += "\nPossibly due to unpredicted return value for some call."
                calls_strs: list[str] = []
                for call in reversed(prophecy.calls):