disallow to disable guard during focus

backend/tests/test_api.py

@@ -125,6 +125,36 @@ def test_invalid_settings_are_rejected(client):
     assert client.put("/api/settings", json={"timezone": "Mars/Olympus"}).status_code == 422
 
 
+def test_switching_the_guard_off_mid_interval_is_a_409(client):
+    assert client.put("/api/settings", json={"blocker": {"enabled": True}}).status_code == 200
+    client.post("/api/timer/start", json={"kind": "work"})
+
+    assert client.get("/api/blocker/policy").json()["locked"] is True
+
+    refused = client.put("/api/settings", json={"blocker": {"enabled": False}})
+    assert refused.status_code == 409
+    assert "focus guard" in refused.json()["detail"]
+
+    # Turning it on, and editing anything else, are both still fine.
+    assert client.put("/api/settings", json={"blocker": {"enabled": True}}).status_code == 200
+    lists = client.put("/api/settings", json={"blocker": {"blocked_apps": ["steam"]}})
+    assert lists.status_code == 200
+    assert lists.json()["settings"]["blocker"]["enabled"] is True
+
+    client.post("/api/timer/complete", json={"auto_next": False})
+    assert client.put("/api/settings", json={"blocker": {"enabled": False}}).status_code == 200
+
+
+def test_resetting_the_settings_cannot_unguard_a_live_interval(client):
+    client.put("/api/settings", json={"blocker": {"enabled": True}})
+    client.post("/api/timer/start", json={"kind": "short_break"})
+
+    assert client.post("/api/settings/reset").status_code == 409
+
+    client.post("/api/timer/complete", json={"auto_next": False})
+    assert client.post("/api/settings/reset").status_code == 200
+
+
 def test_notification_test_endpoint_falls_back_to_the_log(client):
     body = client.post("/api/notifications/test", json={}).json()
     assert body["deliveries"][0]["channel"] == "log"