mizan/backends/mizan-fastapi/tests/test_dispatch.py

"""End-to-end dispatch tests against a real FastAPI app + TestClient."""

from __future__ import annotations

import pytest
from fastapi import FastAPI
from fastapi.exceptions import RequestValidationError
from fastapi.testclient import TestClient
from pydantic import BaseModel

from mizan_core.client.function import client
from mizan_core.registry import clear_registry, register
from mizan_fastapi import (
    MizanError,
    mizan_exception_handler,
    mizan_validation_handler,
    router as mizan_router,
)


# ─── Fixtures ───────────────────────────────────────────────────────────────


class EchoOutput(BaseModel):
    message: str


class SumOutput(BaseModel):
    total: int


class UserOutput(BaseModel):
    email: str
    authenticated: bool


@pytest.fixture
def app():
    """Build a fresh FastAPI app + Mizan router with a few @client functions."""
    clear_registry()

    @client
    def echo(request, text: str) -> EchoOutput:
        return EchoOutput(message=f"echo: {text}")

    @client
    def add(request, a: int, b: int) -> SumOutput:
        return SumOutput(total=a + b)

    @client(context="user")
    def current_user(request) -> UserOutput:
        return UserOutput(email="anon@example.com", authenticated=False)

    @client(context="user")
    def user_count(request) -> SumOutput:
        return SumOutput(total=42)

    @client(affects="user")
    def update_email(request, email: str) -> EchoOutput:
        return EchoOutput(message=f"updated: {email}")

    register(echo, "echo")
    register(add, "add")
    register(current_user, "current_user")
    register(user_count, "user_count")
    register(update_email, "update_email")

    fastapi_app = FastAPI()
    fastapi_app.include_router(mizan_router, prefix="/api/mizan")
    fastapi_app.add_exception_handler(MizanError, mizan_exception_handler)
    fastapi_app.add_exception_handler(RequestValidationError, mizan_validation_handler)

    yield fastapi_app

    clear_registry()


@pytest.fixture
def http(app):
    return TestClient(app)


# ─── RPC dispatch ───────────────────────────────────────────────────────────


class FunctionCallTests:
    def test_simple_call_returns_result(self, http):
        r = http.post("/api/mizan/call/", json={"fn": "echo", "args": {"text": "hi"}})
        assert r.status_code == 200
        body = r.json()
        assert body["result"]["message"] == "echo: hi"
        assert body["invalidate"] == []

    def test_call_with_typed_input(self, http):
        r = http.post("/api/mizan/call/", json={"fn": "add", "args": {"a": 2, "b": 3}})
        assert r.status_code == 200
        assert r.json()["result"]["total"] == 5

    def test_unknown_function_returns_not_found(self, http):
        r = http.post("/api/mizan/call/", json={"fn": "ghost"})
        assert r.status_code == 404
        assert r.json()["error"]["code"] == "NOT_FOUND"

    def test_validation_error_returns_422(self, http):
        r = http.post("/api/mizan/call/", json={"fn": "add", "args": {"a": "not-int", "b": 3}})
        assert r.status_code == 422
        assert r.json()["error"]["code"] == "VALIDATION_ERROR"

    def test_missing_required_input_returns_validation_error(self, http):
        r = http.post("/api/mizan/call/", json={"fn": "add", "args": {}})
        assert r.status_code == 422
        assert r.json()["error"]["code"] == "VALIDATION_ERROR"

    def test_missing_fn_field_returns_400(self, http):
        r = http.post("/api/mizan/call/", json={})
        assert r.status_code == 400
        assert r.json()["error"]["code"] == "BAD_REQUEST"

    def test_invalid_json_returns_400(self, http):
        r = http.post("/api/mizan/call/", content=b"not json", headers={"content-type": "application/json"})
        assert r.status_code == 400

    def test_response_carries_no_store(self, http):
        r = http.post("/api/mizan/call/", json={"fn": "echo", "args": {"text": "x"}})
        assert r.headers.get("cache-control") == "no-store"


# ─── Context bundling ───────────────────────────────────────────────────────


class ContextFetchTests:
    def test_context_returns_bundled_results(self, http):
        r = http.get("/api/mizan/ctx/user/")
        assert r.status_code == 200
        body = r.json()
        assert "current_user" in body
        assert "user_count" in body
        assert body["current_user"]["email"] == "anon@example.com"
        assert body["user_count"]["total"] == 42

    def test_unknown_context_returns_not_found(self, http):
        r = http.get("/api/mizan/ctx/ghost/")
        assert r.status_code == 404
        assert r.json()["error"]["code"] == "NOT_FOUND"


# ─── Invalidation ───────────────────────────────────────────────────────────


class InvalidationTests:
    def test_mutation_emits_invalidate_list(self, http):
        r = http.post(
            "/api/mizan/call/",
            json={"fn": "update_email", "args": {"email": "new@example.com"}},
        )
        assert r.status_code == 200
        body = r.json()
        # affects='user' is a context-name string → invalidate list contains 'user'
        assert "user" in body["invalidate"]