Skip to content

Sayer

Tutorial 3: State, Middleware, and Testing

English

Tutorial 3: State, Middleware, and Testing¶

This tutorial adds production-grade behavior: shared state, middleware hooks, and tests.

Step 1. Add shared state¶

from sayer.state import State


class AppState(State):
    debug: bool = False

Inject it into commands:

@app.command()
def status(state: AppState):
    print(f"debug={state.debug}")

Step 2. Register middleware¶

from sayer.middleware import register


def before(name, args):
    print(f"[before] {name} -> {args}")


def after(name, args, result):
    print(f"[after] {name} -> {result}")


register("audit", before=[before], after=[after])


@app.command(middleware=["audit"])
def ping():
    return "pong"

Step 3. Add tests¶

from sayer.testing import SayerTestClient


def test_ping():
    client = SayerTestClient(app=app)
    result = client.invoke(["ping"], with_return_value=True)
    assert result.exit_code == 0
    assert result.return_value == "pong"

Step 4. Validate behavior¶

pytest -q

What changed¶

State provides shared, injected context.
Middleware adds cross-cutting behavior.
SayerTestClient validates output and return values.

Next¶