added app_test file

Author: Harmanpreet Kaur

src/tests/backend/app_test.py

@@ -0,0 +1,33 @@
+from backend.app import create_app
+
+from fastapi import FastAPI
+
+from httpx import ASGITransport
+from httpx import AsyncClient
+
+import pytest
+
+
+@pytest.fixture
+def app() -> FastAPI:
+    """Fixture to create a test app instance."""
+    return create_app()
+
+
+@pytest.mark.asyncio
+async def test_health_check(app: FastAPI):
+    """Test the /health endpoint returns a healthy status."""
+    transport = ASGITransport(app=app)
+    async with AsyncClient(transport=transport, base_url="http://test") as ac:
+        response = await ac.get("/health")
+    assert response.status_code == 200
+    assert response.json() == {"status": "healthy"}
+
+
+@pytest.mark.asyncio
+async def test_backend_routes_exist(app: FastAPI):
+    """Ensure /api routes are available (smoke test)."""
+    # Check available routes include /api prefix from backend_router
+    routes = [route.path for route in app.router.routes]
+    backend_routes = [r for r in routes if r.startswith("/api")]
+    assert backend_routes, "No backend routes found under /api prefix"