🐛 fix:Alias resolving

[StummeJ]

This fixes an issue where you register a alias with the class name and try to build the provider. It looks like it tries to solve the resolver before it adds aliases to the map, which causes an exception, even though it is available in the aliases

[RobertoPrevato]

Hi @StummeJ
The proposed change is giving a different meaning to the aliases. Aliases were added so that people who don't want to use type annotations, can use the library without them, or for situations when it is desirable to resolve a type by variable name.

The example is doing something wrong when defining the factory and registering it:

def test_alias_dep_resolving():
    container = arrange_cats_example()

    class BaseClass:
        pass

    class DerivedClass(BaseClass):
        pass

    class UsingAliasByType:
        def __init__(self, example: BaseClass):
            self.example = example

    def resolve_derived_class(_) -> DerivedClass:
        return DerivedClass()

    container.add_scoped_by_factory(resolve_derived_class, DerivedClass)
    container.add_alias("BaseClass", DerivedClass)
    container.add_scoped(UsingAliasByType)

    provider = container.build_provider()
    u = provider.get(UsingAliasByType)

    assert isinstance(u, UsingAliasByType)
    assert isinstance(u.example, DerivedClass)

    b = provider.get(BaseClass)
    assert isinstance(b, DerivedClass)

It should be written in a simpler way:

-    def resolve_derived_class(_) -> DerivedClass:
+    def resolve_derived_class(_) -> BaseClass:^M
         return DerivedClass()
 
-    container.add_scoped_by_factory(resolve_derived_class, DerivedClass)
-    container.add_alias("BaseClass", DerivedClass)
+    container.add_scoped_by_factory(resolve_derived_class)

The objective is to resolve BaseClass with DerivedClass, so the user should register a factory that declares a return type of BaseClass and returns an instance of DerivedClass.

def test_alias_dep_resolving():
    container = arrange_cats_example()

    class BaseClass:
        pass

    class DerivedClass(BaseClass):
        pass

    class UsingAliasByType:
        def __init__(self, example: BaseClass):
            self.example = example

    def resolve_derived_class(_) -> BaseClass:
        return DerivedClass()

    container.add_scoped_by_factory(resolve_derived_class)
    container.add_scoped(UsingAliasByType)

    provider = container.build_provider()
    u = provider.get(UsingAliasByType)

    assert isinstance(u, UsingAliasByType)
    assert isinstance(u.example, DerivedClass)

    b = provider.get(BaseClass)
    assert isinstance(b, DerivedClass)

Besides, aliases are meant to support this kind of scenario, without type annotations:

     class UsingAliasByType:
-        def __init__(self, example: BaseClass):
+        def __init__(self, example):  # <-- missing type annotation for example^M
             self.example = example
 
-    def resolve_derived_class(_) -> DerivedClass:
+    def resolve_derived_class(_) -> BaseClass:^M
         return DerivedClass()
 
-    container.add_scoped_by_factory(resolve_derived_class, DerivedClass)
-    container.add_alias("BaseClass", DerivedClass)
+    container.add_scoped_by_factory(resolve_derived_class)^M
+    container.add_alias("example", BaseClass)  #<-- add alias to resolve type by variable name

def test_alias_dep_resolving():
    container = arrange_cats_example()

    class BaseClass:
        pass

    class DerivedClass(BaseClass):
        pass

    class UsingAliasByType:
        def __init__(self, example):  # <-- missing type annotation for the example variable
            self.example = example

    def resolve_derived_class(_) -> BaseClass:
        return DerivedClass()

    container.add_scoped_by_factory(resolve_derived_class)
    container.add_alias("example", BaseClass)  # <-- add alias to resolve to the desired type
    container.add_scoped(UsingAliasByType)

    provider = container.build_provider()
    u = provider.get(UsingAliasByType)

    assert isinstance(u, UsingAliasByType)
    assert isinstance(u.example, DerivedClass)

    b = provider.get(BaseClass)
    assert isinstance(b, DerivedClass)

I don't want to merge this PR, sorry.