Deduplicate scan ended telemetry

tests/test_telemetry.py

@@ -0,0 +1,39 @@
+"""Tests for scan telemetry emission."""
+
+from __future__ import annotations
+
+from typing import Any
+
+import pytest
+
+from strix.report.state import ReportState
+from strix.telemetry import posthog, scarf
+
+
+@pytest.mark.parametrize(
+    ("backend", "sent_attribute"),
+    [
+        (posthog, "posthog_scan_ended_sent"),
+        (scarf, "scarf_scan_ended_sent"),
+    ],
+)
+def test_scan_ended_is_sent_once_per_backend(
+    monkeypatch: pytest.MonkeyPatch,
+    backend: Any,
+    sent_attribute: str,
+) -> None:
+    state = ReportState(run_name="test-run")
+    sent_events: list[tuple[str, dict[str, Any]]] = []
+    monkeypatch.setattr(
+        backend,
+        "_send",
+        lambda event, properties: sent_events.append((event, properties)),
+    )
+
+    backend.end(state, exit_reason="finished_by_tool")
+    backend.end(state, exit_reason="user_exit")
+
+    assert getattr(state, sent_attribute) is True
+    assert len(sent_events) == 1
+    assert sent_events[0][0] == "scan_ended"
+    assert sent_events[0][1]["exit_reason"] == "finished_by_tool"