add unittest to see the code fail

test/randomized_benchmarking/test_randomized_benchmarking.py

@@ -16,6 +16,7 @@
 
 import numpy as np
 from ddt import ddt, data, unpack
+from qiskit.circuit import Delay, QuantumCircuit
 from qiskit.circuit.library import SXGate, CXGate, TGate, XGate
 from qiskit.exceptions import QiskitError
 from qiskit.providers.aer import AerSimulator
@@ -266,6 +267,25 @@ def test_expdata_serialization(self):
 class TestInterleavedRB(RBTestCase):
     """Test for interleaved RB."""
 
+    def test_interleaved_element_with_delay(self):
+        """Test building RB sequence interleaved with delay or circuit with delay"""
+        exp = rb.InterleavedRB(
+            interleaved_element=Delay(10, unit="us"),
+            qubits=[0],
+            lengths=[1, 2, 3],
+            seed=123,
+            num_samples=2,
+        )
+        exp.circuits()
+
+        delay_qc = QuantumCircuit(2)
+        delay_qc.delay(10, [0, 1], "us")
+
+        exp = rb.InterleavedRB(
+            interleaved_element=delay_qc, qubits=[1, 2], lengths=[1, 2, 3], seed=123, num_samples=2
+        )
+        exp.circuits()
+
     @data([XGate(), [3], 4], [CXGate(), [4, 7], 5])
     @unpack
     def test_interleaved_structure(self, interleaved_element, qubits, length):