merge: testing → main (reconcile 2-week divergence)

tests/api/test_sse_limits.py

@@ -0,0 +1,60 @@
+"""Per-user SSE connection cap — F6/D mitigation."""
+import pytest
+from fastapi import HTTPException
+
+from decnet.web import sse_limits
+
+
+@pytest.mark.asyncio
+async def test_slot_under_cap_enters_cleanly(monkeypatch):
+    monkeypatch.setattr(sse_limits, "_MAX_PER_USER", 2)
+    sse_limits._reset_for_tests()
+
+    async with sse_limits.sse_connection_slot("u1"):
+        assert sse_limits.current_count("u1") == 1
+        async with sse_limits.sse_connection_slot("u1"):
+            assert sse_limits.current_count("u1") == 2
+
+    assert sse_limits.current_count("u1") == 0
+
+
+@pytest.mark.asyncio
+async def test_slot_over_cap_raises_429(monkeypatch):
+    monkeypatch.setattr(sse_limits, "_MAX_PER_USER", 1)
+    sse_limits._reset_for_tests()
+
+    async with sse_limits.sse_connection_slot("u1"):
+        with pytest.raises(HTTPException) as exc:
+            async with sse_limits.sse_connection_slot("u1"):
+                pass
+        assert exc.value.status_code == 429
+
+    # Released after the outer context exits → fresh slot works.
+    async with sse_limits.sse_connection_slot("u1"):
+        assert sse_limits.current_count("u1") == 1
+
+
+@pytest.mark.asyncio
+async def test_slot_per_user_isolation(monkeypatch):
+    monkeypatch.setattr(sse_limits, "_MAX_PER_USER", 1)
+    sse_limits._reset_for_tests()
+
+    async with sse_limits.sse_connection_slot("u1"):
+        async with sse_limits.sse_connection_slot("u2"):
+            assert sse_limits.current_count("u1") == 1
+            assert sse_limits.current_count("u2") == 1
+
+
+@pytest.mark.asyncio
+async def test_slot_decrements_on_exception(monkeypatch):
+    monkeypatch.setattr(sse_limits, "_MAX_PER_USER", 1)
+    sse_limits._reset_for_tests()
+
+    with pytest.raises(ValueError):
+        async with sse_limits.sse_connection_slot("u1"):
+            raise ValueError("boom")
+
+    assert sse_limits.current_count("u1") == 0
+    # Slot is free again after exception path.
+    async with sse_limits.sse_connection_slot("u1"):
+        pass