decomposer: generate files for Maintain only the latest check result for each monitored target in concurrency-safe memory and expose it through the specified FastAPI current-status endpoint.

tests/test_api.py

@@ -0,0 +1,56 @@
+from fastapi import FastAPI
+from httpx import ASGITransport, AsyncClient
+
+from current_status import CurrentStatusCoordinator, build_current_status_router
+
+
+def app_for(coordinator: CurrentStatusCoordinator) -> FastAPI:
+    app = FastAPI()
+    app.include_router(build_current_status_router(coordinator))
+    return app
+
+
+async def test_not_found_and_no_check_yet_are_distinct() -> None:
+    coordinator = CurrentStatusCoordinator()
+    async with AsyncClient(
+        transport=ASGITransport(app=app_for(coordinator)), base_url="http://test"
+    ) as client:
+        missing = await client.get("/targets/missing/status")
+        assert missing.status_code == 404
+        assert missing.json() == {
+            "detail": {"code": "target_not_found", "target_id": "missing"}
+        }
+
+        await coordinator.register_target("new")
+        pending = await client.get("/targets/new/status")
+        assert pending.status_code == 200
+        assert pending.json() == {
+            "target_id": "new",
+            "state": "not_checked",
+            "result": None,
+        }
+
+
+async def test_endpoint_returns_only_latest_result() -> None:
+    coordinator = CurrentStatusCoordinator()
+    await coordinator.register_target("web")
+
+    async def first(_target):
+        return {"up": False}
+
+    async def second(_target):
+        return {"up": True, "status_code": 204}
+
+    assert await coordinator.run_check("web", {}, first)
+    assert await coordinator.run_check("web", {}, second)
+    assert await coordinator.retained_status_count() == 1
+
+    async with AsyncClient(
+        transport=ASGITransport(app=app_for(coordinator)), base_url="http://test"
+    ) as client:
+        response = await client.get("/targets/web/status")
+    assert response.status_code == 200
+    body = response.json()
+    assert body["state"] == "checked"
+    assert body["result"]["payload"] == {"up": True, "status_code": 204}
+    assert body["result"]["check_sequence"] == 2