Add unit tests for RequestId and Exception Handling Middlewares

api-server/tests/test_middlewares.py

@@ -0,0 +1,84 @@
+import uuid
+import pytest
+from fastapi import FastAPI, Request
+from fastapi.responses import JSONResponse
+from fastapi.testclient import TestClient
+
+# Import your middleware classes here
+from app.middlewares.request_id_middleware import RequestIdMiddleware
+from app.middlewares.unhandled_exceptions_middleware import UnhandledExceptionsMiddleware
+
+# --- Dummy endpoint that returns OK JSON ---
+async def ok_endpoint(request: Request):
+    # When called, respond with JSON {"status": "ok"}
+    return JSONResponse({"status": "ok"})
+
+# --- Dummy endpoint that raises an exception ---
+async def fail_endpoint(request: Request):
+    # When called, raise a ValueError to simulate an error
+    raise ValueError("oops")
+
+@pytest.fixture
+def client():
+    """
+    This pytest fixture sets up a test app instance with the middlewares added,
+    and returns a TestClient which simulates HTTP requests to the app.
+    """
+    app = FastAPI()
+
+    # Add middlewares. Order matters! Exceptions should be handled outermost.
+    app.add_middleware(UnhandledExceptionsMiddleware)
+    app.add_middleware(RequestIdMiddleware)
+
+    # Add routes tied to the dummy endpoints above
+    app.add_api_route("/ok", ok_endpoint, methods=["GET"])
+    app.add_api_route("/fail", fail_endpoint, methods=["GET"])
+
+    # Return a test client wrapping the ASGI app for test requests
+    return TestClient(app)
+
+def test_request_id_auto_generated(client):
+    """
+    Test that when no 'x-exosphere-request-id' header is sent, the RequestIdMiddleware
+    automatically generates a valid UUID and returns it in the response headers.
+    """
+    resp = client.get("/ok")  # Make GET request without headers
+    assert resp.status_code == 200  # Should return HTTP 200 OK
+
+    rid = resp.headers["x-exosphere-request-id"]  # Get the request ID from headers
+    uuid.UUID(rid)  # Validate that it is a valid UUID (will raise an exception if not)
+
+    assert resp.json() == {"status": "ok"}  # Response body should be unchanged
+
+def test_request_id_echoed_when_valid(client):
+    """
+    Test that when a valid UUID is provided in header, middleware preserves (echoes) it.
+    """
+    provided = str(uuid.uuid4())  # Generate a valid UUID string
+    resp = client.get("/ok", headers={"x-exosphere-request-id": provided})  # Send header
+
+    assert resp.headers["x-exosphere-request-id"] == provided  # Header echoed exactly
+
+def test_request_id_replaced_when_invalid(client):
+    """
+    Test that when an invalid request ID is sent, middleware replaces it with a valid UUID.
+    """
+    resp = client.get("/ok", headers={"x-exosphere-request-id": "invalid-id"})  # Send bad header
+
+    new_rid = resp.headers["x-exosphere-request-id"]
+    assert new_rid != "invalid-id"  # Confirm the invalid ID was replaced
+    uuid.UUID(new_rid)  # Confirm replacement is a valid UUID
+
+def test_unhandled_exception_caught(client):
+    """
+    Test that any unhandled exception during request processing is caught by the middleware,
+    returning a JSON error with HTTP status 500, and still providing a request ID header.
+    """
+    resp = client.get("/fail")  # This route raises an exception
+
+    assert resp.status_code == 500  # Middleware converts error to HTTP 500 response
+
+    body = resp.json()
+    assert "error" in body or "detail" in body  # Error info present in JSON response body
+
+    assert "x-exosphere-request-id" in resp.headers  # Request ID header is still present