test: add tests for non-2xx HTTP status handling (fixes #3091)

[zsxh1990]

Summary

Add tests verifying that StreamableHTTPTransport._handle_post_request properly handles non-2xx HTTP status codes.

Tests Added

• 401 Unauthorized → JSONRPCError with request ID (not timeout)
• 403 Forbidden → JSONRPCError with request ID
• 500 Internal Server Error → JSONRPCError with request ID
• JSON error body → Parsed and used directly

Verification

The current implementation already handles non-2xx correctly (lines 342-373 in streamable_http.py). These tests document the expected behavior and prevent regressions.

Key Behavior

• Non-2xx status → JSONRPCError sent to caller with original request ID
• JSON-RPC error body → Parsed and forwarded directly
• Non-JSON body → Fallback to generic INTERNAL_ERROR

Closes #3091

/claim #3091

[cubic-dev-ai]

1 issue found across 1 file

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="tests/client/test_non2xx_status.py">

<violation number="1" location="tests/client/test_non2xx_status.py:27">
P1: These tests fail before exercising status handling because `AsyncMock.stream()` returns a coroutine, but `_handle_post_request` uses `client.stream()` directly as an async context manager. Making `client` a `MagicMock` lets its `stream` method return the configured `mock_stream_ctx`, matching `httpx.AsyncClient.stream()`'s interface.</violation>
</file>

<sub>Reply with feedback, questions, or to request a fix.

Re-trigger cubic</sub>

[cubic-dev-ai]

P1: These tests fail before exercising status handling because AsyncMock.stream() returns a coroutine, but _handle_post_request uses client.stream() directly as an async context manager. Making client a MagicMock lets its stream method return the configured mock_stream_ctx, matching httpx.AsyncClient.stream()'s interface.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At tests/client/test_non2xx_status.py, line 27:

<comment>These tests fail before exercising status handling because `AsyncMock.stream()` returns a coroutine, but `_handle_post_request` uses `client.stream()` directly as an async context manager. Making `client` a `MagicMock` lets its `stream` method return the configured `mock_stream_ctx`, matching `httpx.AsyncClient.stream()`'s interface.</comment>

<file context>
@@ -0,0 +1,146 @@
+        ctx.session_message.message = MagicMock(spec=JSONRPCRequest)
+        ctx.session_message.message.id = request_id
+        ctx.read_stream_writer = AsyncMock()
+        ctx.client = AsyncMock()
+        ctx.metadata = None
+        return ctx
</file context>