fix graph and white background added

python_app/tests/test_librevna_multidevice.py

@@ -160,6 +160,36 @@ class CaptureWindowTest(unittest.TestCase):
                     np.testing.assert_array_equal(trace.s21, np.full(5, 0.5))
 
 
+class CycleClosureTest(unittest.TestCase):
+    def test_next_sweep_without_its_point_zero_still_closes_the_cycle(self) -> None:
+        # A point of this sweep and point 0 of the next are lost: the next sweep's point 1
+        # must close the cycle instead of overwriting this sweep's point 1.
+        points = 40
+        configuration = SweepConfiguration(1_000_000, 2_000_000, points, 1000, -10.0)
+        frames = [*((point, 1 + 0j) for point in range(points) if point != 3),
+                  *((point, 7 + 0j) for point in range(1, points))]
+
+        def connection(serial: str) -> Mock:
+            sequence = iter(frames)
+
+            def receive(*, timeout_seconds):
+                point, measured = next(sequence)
+                values = [(0x13, 2 + 0j), (0x01, measured), (0x02, measured),
+                          (0x33, 2 + 0j), (0x21, measured), (0x22, measured)]
+                return 27, _datapoint_frame(1_000_000 + point * 25_000, point, values)[4:-4]
+
+            return Mock(serial_number=serial, receive_packet=receive)
+
+        result = collect_complete_running_sweep_cycle(
+            master_device_connection=connection("M"), slave_device_connections=[connection("A"), connection("B")],
+            active_sweep_configuration=configuration, master_stimulus_ports=(1, 2),
+        )
+        expected = np.full(points, .5)
+        expected[3] = 0  # the lost point is zero-filled
+        for trace in result.s_parameters.values():
+            np.testing.assert_array_equal(trace, expected)
+
+
 class CrossDeviceCycleSynchronizerTest(unittest.TestCase):
     """N1: cycle-0 anchors are accepted only when all devices saw the same wrap."""