Hermes-agent

tests/tui_gateway/test_wait_for_mcp_discovery.py

@@ -0,0 +1,78 @@
+"""Tests for tui_gateway.entry.wait_for_mcp_discovery (PR #35245).
+
+MCP tool discovery runs in a background daemon thread so a slow/dead server
+can't freeze ``gateway.ready``.  The agent snapshots its tool list once at
+build time and never re-reads it, so ``_make_agent`` briefly joins the
+discovery thread before building — bounded, so a dead server can't re-introduce
+the startup hang, and a no-op once discovery has finished.
+"""
+
+import threading
+import time
+
+import tui_gateway.entry as entry
+
+
+def _restore_thread_slot(saved):
+    entry._mcp_discovery_thread = saved
+
+
+def test_no_thread_is_noop():
+    """When no discovery thread was started (the common no-MCP case), the
+    helper returns immediately and never blocks."""
+    saved = entry._mcp_discovery_thread
+    try:
+        entry._mcp_discovery_thread = None
+        start = time.monotonic()
+        entry.wait_for_mcp_discovery(timeout=5.0)
+        assert time.monotonic() - start < 0.1
+    finally:
+        _restore_thread_slot(saved)
+
+
+def test_already_finished_thread_is_noop():
+    """A thread that has already finished is not joined-on (dead thread)."""
+    saved = entry._mcp_discovery_thread
+    try:
+        t = threading.Thread(target=lambda: None, daemon=True)
+        t.start()
+        t.join()  # ensure it's finished
+        entry._mcp_discovery_thread = t
+        start = time.monotonic()
+        entry.wait_for_mcp_discovery(timeout=5.0)
+        assert time.monotonic() - start < 0.1
+    finally:
+        _restore_thread_slot(saved)
+
+
+def test_fast_thread_is_joined():
+    """A reachable-but-still-connecting (fast) server lands before the agent
+    snapshots tools — the helper waits for it to finish."""
+    saved = entry._mcp_discovery_thread
+    try:
+        t = threading.Thread(target=lambda: time.sleep(0.05), daemon=True)
+        t.start()
+        entry._mcp_discovery_thread = t
+        entry.wait_for_mcp_discovery(timeout=1.0)
+        assert not t.is_alive()  # joined to completion
+    finally:
+        _restore_thread_slot(saved)
+
+
+def test_hung_thread_is_bounded_by_timeout():
+    """A slow/dead server must NOT re-introduce the startup hang — the join is
+    bounded by the timeout and returns even though the thread is still alive."""
+    saved = entry._mcp_discovery_thread
+    stop = threading.Event()
+    try:
+        t = threading.Thread(target=stop.wait, daemon=True)  # blocks until set
+        t.start()
+        entry._mcp_discovery_thread = t
+        start = time.monotonic()
+        entry.wait_for_mcp_discovery(timeout=0.3)
+        elapsed = time.monotonic() - start
+        assert 0.25 <= elapsed < 1.0  # bounded near the timeout, not forever
+        assert t.is_alive()  # thread still running; we did not block on it
+    finally:
+        stop.set()
+        _restore_thread_slot(saved)