Bug 1953541

python-molten fails to build with Python 3.10.0a7.

=================================== FAILURES ===================================
_____________ test_apps_can_be_injected_into_singleton_components ______________

    def test_apps_can_be_injected_into_singleton_components():
        # Given that I have a singleton component that requests the app
        class AClass:  # noqa
            def __init__(self, app):
                self.app = app
    
        class AComponent:
            is_cacheable = True
            is_singleton = True
    
            def can_handle_parameter(self, parameter):
                return parameter.annotation is AClass
    
            def resolve(self, app: BaseApp):
                return AClass(app)
    
        app = App(components=[AComponent()])
    
        # When I resolve that component
        def test(a_class: AClass):
            # Then its app property should be the app instance
            assert a_class.app is app
    
        resolver = app.injector.get_resolver()
>       resolver.resolve(test)()

tests/test_app.py:501: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

params = {}, parameter = <Parameter "a_class: 'AClass'">
component = <molten.components.UploadedFileComponent object at 0x7fc6b9e22f50>

    @functools.wraps(fn)
    def resolved_fn(**params: Any) -> Any:
        for parameter in _get_parameters(fn):
            if parameter.name in params:
                continue
    
            # When Parameter is requested then we assume that the
            # caller actually wants the parameter that resolved the
            # current component that's being resolved.  See QueryParam
            # or Header components for an example.
            if parameter.annotation is Parameter:
                params[parameter.name] = resolving_parameter
                continue
    
            # When a DependencyResolver is requested, then we assume
            # the caller wants this instance.
            if parameter.annotation is DependencyResolver:
                params[parameter.name] = self
                continue
    
            # If our instances contains an exact match for a type,
            # then we return that.  This is used to inject the current
            # Request object among other things.
            try:
                params[parameter.name] = self.instances[parameter.annotation]
                continue
            except KeyError:
                pass
    
            for component in self.components:
                if component.can_handle_parameter(parameter):
                    try:
                        params[parameter.name] = self.instances[component]
                    except KeyError:
                        factory = self.resolve(component.resolve, resolving_parameter=parameter)
                        params[parameter.name] = instance = factory()
    
                        if getattr(component, "is_cacheable", True):
                            self.instances[component] = instance
    
                    break
            else:
>               raise DIError(f"cannot resolve parameter {parameter} of function {fn}")
E               molten.errors.DIError: cannot resolve parameter a_class: 'AClass' of function <function test_apps_can_be_injected_into_singleton_components.<locals>.test at 0x7fc6b9701a20>

molten/dependency_injection.py:189: DIError

---------- coverage: platform linux, python 3.10.0-alpha-7 -----------
Coverage HTML written to dir htmlcov

=========================== short test summary info ============================
FAILED tests/test_app.py::test_apps_can_be_injected_into_singleton_components
======================== 1 failed, 247 passed in 2.62s =========================

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.10/fedora-rawhide-x86_64/02143294-python-molten/

For all our attempts to build python-molten with Python 3.10, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.10/package/python-molten/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.10:
https://copr.fedorainfracloud.org/coprs/g/python/python3.10/

Let us know here if you have any questions.

Python 3.10 will be included in Fedora 35. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.10.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.