coredevice: adf5356: add test for failed PLL lock

Signed-off-by: Etienne Wodey <wodey@iqo.uni-hannover.de>

artiq/test/coredevice/test_adf5356.py

@@ -62,6 +62,17 @@ class ADF5356Exp(EnvExperiment):
         delay(5 * ms)
         self.set_dataset("muxout", self.dev.read_muxout())
 
+    @kernel
+    def muxout_lock_detect_no_lock(self):
+        self.core.break_realtime()
+        self.dev.cpld.init()
+        self.dev.init()
+        # set external SMA reference input
+        self.dev.cpld.write_reg(1, (1 << 4))
+        self.dev.set_frequency(100 * MHz)
+        delay(5 * ms)
+        self.set_dataset("muxout", self.dev.read_muxout())
+
     @kernel
     def set_get_output_power(self):
         self.core.break_realtime()
@@ -168,6 +179,11 @@ class ADF5356Test(ExperimentCase):
         muxout = self.dataset_mgr.get("muxout")
         self.assertTrue(muxout)
 
+    def test_muxout_lock_detect_no_lock(self):
+        self.execute(ADF5356Exp, "muxout_lock_detect_no_lock")
+        muxout = self.dataset_mgr.get("muxout")
+        self.assertFalse(muxout)
+
     def test_set_too_high_frequency(self):
         with self.assertRaises(ValueError):
             self.execute(ADF5356Exp, "set_too_high_frequency")