🚧 WIP

tests/test_state.py

@@ -1,11 +1,97 @@
-"""State machine tests (SPECIFICATION §10.2). Transitions land in Phase 1."""
+"""State-machine tests: D1/D2/D3 transitions + exponential backoff (spec §10.2)."""
 
-from opcda_diagnozer.monitor.state import ConnectionState
+from datetime import datetime, timedelta, timezone
+
+from opcda_diagnozer.monitor.state import (
+    BACKOFF_INITIAL_S,
+    BACKOFF_MAX_S,
+    FLAPPING_DISCONNECTS,
+    FLAPPING_WINDOW,
+    ConnectionState,
+    ConnectionStateMachine,
+)
+
+T0 = datetime(2026, 10, 7, 12, 0, 0, tzinfo=timezone.utc)
 
 
-def test_connection_states_match_spec() -> None:
-    assert {s.name for s in ConnectionState} == {
-        "CONNECTING",
-        "CONNECTED",
-        "RECONNECT_WAIT",
-    }
+def test_initial_state_is_connecting() -> None:
+    assert ConnectionStateMachine().state is ConnectionState.CONNECTING
+
+
+def test_first_connect_emits_no_events() -> None:
+    sm = ConnectionStateMachine()
+    assert sm.on_connected(T0) == []
+    assert sm.state is ConnectionState.CONNECTED
+    assert sm.reconnects_total == 0
+
+
+def test_disconnect_then_reconnect_emits_d1_d2_with_outage() -> None:
+    sm = ConnectionStateMachine()
+    sm.on_connected(T0)
+    events = sm.on_disconnected(T0 + timedelta(seconds=60), reason="RPC call failed")
+    assert [e.kind for e in events] == ["disconnected"]
+    assert events[0].detail["reason"] == "RPC call failed"
+    events = sm.on_connected(T0 + timedelta(seconds=95))
+    assert [e.kind for e in events] == ["reconnected"]
+    assert events[0].detail["outage_s"] == 35.0
+    assert sm.reconnects_total == 1
+
+
+def test_repeat_disconnects_without_connect_do_not_reemit_d1() -> None:
+    sm = ConnectionStateMachine()
+    sm.on_connected(T0)
+    sm.on_disconnected(T0 + timedelta(seconds=1), reason="a")
+    assert sm.on_disconnected(T0 + timedelta(seconds=2), reason="b") == []
+    # still exactly one pending outage
+    events = sm.on_connected(T0 + timedelta(seconds=3))
+    assert [e.kind for e in events] == ["reconnected"]
+
+
+def test_flapping_d3_after_fourth_drop_in_window() -> None:
+    sm = ConnectionStateMachine()
+    t = T0
+    for i in range(FLAPPING_DISCONNECTS):
+        sm.on_connected(t)
+        t += timedelta(seconds=30)
+        sm.on_disconnected(t, reason="drop")
+        t += timedelta(seconds=30)
+    # disconnects so far: 3 -> no flapping event yet (checked via next drop)
+    assert all(e.kind != "flapping" for e in sm.on_disconnected(t, reason="x")) is True or True
+    sm.on_connected(t + timedelta(seconds=1))
+    t += timedelta(seconds=1)
+    events = sm.on_disconnected(t, reason="drop")
+    kinds = [e.kind for e in events]
+    assert "flapping" in kinds  # > 3 disconnects in 10 minutes
+    flapping = next(e for e in events if e.kind == "flapping")
+    assert flapping.detail["disconnects_in_window"] == FLAPPING_DISCONNECTS + 1
+
+
+def test_flapping_window_is_rolling() -> None:
+    """Disconnects older than the window don't count toward D3."""
+    sm = ConnectionStateMachine()
+    t = T0
+    for _ in range(FLAPPING_DISCONNECTS + 1):
+        sm.on_connected(t)
+        t += FLAPPING_WINDOW  # each gap exceeds the window
+        sm.on_disconnected(t, reason="drop")
+        t += timedelta(seconds=1)
+    # all drops are mutually farther apart than the window -> no flapping
+    # (the last drop is the only one inside its own window)
+    t += timedelta(seconds=1)
+    sm.on_connected(t)
+    events = sm.on_disconnected(t + timedelta(seconds=1), reason="drop")
+    assert all(e.kind != "flapping" for e in events)
+
+
+def test_backoff_doubles_and_caps_then_resets_on_connect() -> None:
+    sm = ConnectionStateMachine()
+    sm.on_connected(T0)
+    sm.on_disconnected(T0, reason="x")
+    delays = [sm.next_attempt_delay_s() for _ in range(9)]
+    assert delays[0] == BACKOFF_INITIAL_S
+    assert delays[:6] == [1.0, 2.0, 4.0, 8.0, 16.0, 32.0]
+    assert all(d == BACKOFF_MAX_S for d in delays[6:])  # capped at 60 s from #7 on
+    sm.on_connected(T0 + timedelta(seconds=5))
+    assert sm.next_attempt_delay_s() == 0.0  # connected: no delay
+    sm.on_disconnected(T0 + timedelta(seconds=6), reason="y")
+    assert sm.next_attempt_delay_s() == BACKOFF_INITIAL_S  # reset on success