MCP integration tests don't verify static assets are served

[paddymul]

Problem

The MCP integration tests (test_mcp_uvx_install.py) stop at tools/list — they never call tools/call view_data. The proposed test_view_data_call test would close that gap, but even it wouldn't catch missing static assets like widget.js / standalone.js.

The view_data tool's data path (ensure_server() → Tornado → POST /load → text summary) works fine without the JS bundle. The failure only surfaces when a browser loads the session page and tries to fetch the JS. This means a broken wheel (missing static files) passes all MCP protocol tests.

How this bit us

When widget.js was missing from a fresh install, view_data appeared to work (the MCP text response came back) but the browser page it opened was blank. No test caught it.

Suggested fix

After calling tools/call view_data through the MCP protocol, also HTTP-fetch the static JS asset from the Tornado server that ensure_server() started. Something like:

1. Parse the view_data response to extract the server URL / port
2. GET /static/standalone.js (or whatever the entry point is)
3. Assert 200 and non-empty body

This would verify the full user-visible path: MCP protocol → server startup → data load → static assets present.

Alternatively

A simpler check: after installing the wheel, assert the static file exists on disk inside the installed package directory. This is less end-to-end but faster and doesn't need a running server.

[paddymul]

Implementation Plan

Overview

Extend MCP integration tests to verify that view_data returns HTML referencing static assets and that those assets are served correctly.

Steps

1. Add test_view_data_returns_html in tests/integration_notebooks/test_mcp_uvx_install.py:

   • Call tools/call view_data with a sample DataFrame
   • Assert the response contains HTML with <script> tags referencing widget.js or standalone.js

2. Add test_static_assets_served:

   • Extract the asset URLs from the HTML response
   • Make HTTP GET requests to each URL
   • Assert 200 status and non-empty body
   • Verify Content-Type headers (e.g. application/javascript)

3. Add test_view_data_renders_data:

   • Verify the HTML/JS payload includes the actual DataFrame data (check for column names, sample values in the serialized payload)

4. CI — these tests should run in the existing MCP integration test job. May need a running data server fixture.

Files to modify

• tests/integration_notebooks/test_mcp_uvx_install.py — new test functions
• May need a test fixture to start/stop the data server

@codex

[chatgpt-codex-connector]

Summary

• Added reusable MCP integration helpers to parse the Interactive view URL, extract script asset URLs from session HTML, perform HTTP fetches, invoke tools/call view_data, and read initial WebSocket state (with optional tornado imports via pytest.importorskip to avoid collection-time dependency failures). tests/unit/server/test_mcp_uvx_install.pyL185-L240
• Added test_view_data_returns_html to verify that a real view_data invocation leads to a session HTML page containing <script> tags and a JS bundle reference (standalone.js/widget.js). tests/unit/server/test_mcp_uvx_install.pyL522-L554
• Added test_static_assets_served to parse script asset URLs from that HTML and assert each target JS asset is served with HTTP 200, non-empty body, and JavaScript content type. tests/unit/server/test_mcp_uvx_install.pyL555-L597
• Added test_view_data_renders_data to connect to the session WebSocket and verify the initial_state payload contains expected loaded data markers (column/value checks: name, Alice). tests/unit/server/test_mcp_uvx_install.pyL598-L629

Testing

• ⚠️ pytest -q tests/unit/server/test_mcp_uvx_install.py -k 'view_data_returns_html or static_assets_served or view_data_renders_data' -m slow (failed in this environment because uvx-backed MCP startup could not complete/initialize here).
• ✅ python -m py_compile tests/unit/server/test_mcp_uvx_install.py

View task →

[paddymul]

Status: Already implemented on main

MCP integration tests were added in PR #572 (commit fdbe325):

• tests/unit/server/test_mcp_server_integration.py (494 lines) with comprehensive process-level tests
• Tests real server subprocess lifecycle, version mismatch handling, port conflicts, reuse
• Static asset verification in buckaroo/mcp_tool.py lines 237-244 checks static file existence and size
• Health check includes static_files status reporting

Recommend closing this issue.