Overrides

The simplest (and most reliable) testing strategy is:

• create a fresh diwire.Container per test

• register test doubles (fakes/mocks) up front

• resolve your entrypoint (service/handler) from that container

Override by registering again

Registrations are replaceable. In general, override before the first resolve:

from typing import Protocol

from diwire import Container, Lifetime

container = Container()

class EmailClient(Protocol):
    def send(self, to: str, subject: str) -> None: ...


class RealEmailClient:
    def send(self, to: str, subject: str) -> None:
        ...


class FakeEmailClient:
    def send(self, to: str, subject: str) -> None:
        ...


container.add(RealEmailClient, provides=EmailClient,
    lifetime=Lifetime.SCOPED,
)
# In tests: override BEFORE resolving anything that depends on it.
container.add(FakeEmailClient, provides=EmailClient,
    lifetime=Lifetime.SCOPED,
)

Override using an instance (force a singleton)

Registering an instance is a great way to override something even if it was resolved earlier:

fake = FakeEmailClient()
container.add_instance(fake, provides=EmailClient)

Because the container uses the instance directly, subsequent resolves return exactly that object.