Add missing delay instruction to fake backends

qiskit/test/mock/utils/backend_converter.py

@@ -21,6 +21,7 @@
 from qiskit.circuit.library.standard_gates import IGate, SXGate, XGate, CXGate, RZGate
 from qiskit.circuit.parameter import Parameter
 from qiskit.circuit.gate import Gate
+from qiskit.circuit.delay import Delay
 from qiskit.circuit.measure import Measure
 from qiskit.circuit.reset import Reset
 from qiskit.providers.models.pulsedefaults import PulseDefaults
@@ -43,6 +44,7 @@ def convert_to_target(conf_dict: dict, props_dict: dict = None, defs_dict: dict
     if props_dict:
         qubit_props = qubit_props_from_props(props_dict)
     target = Target(qubit_properties=qubit_props)
+    target.add_instruction(Delay(Parameter("t")))
     # Parse from properties if it exsits
     if props_dict is not None:
         # Parse instructions

test/python/providers/test_fake_backends.py

@@ -25,6 +25,7 @@
 from qiskit.execute_function import execute
 from qiskit.test.base import QiskitTestCase
 from qiskit.test.mock import FakeProviderForBackendV2, FakeProvider
+from qiskit.test.mock import FakeMumbaiV2
 from qiskit.utils import optionals
 
 FAKE_PROVIDER_FOR_BACKEND_V2 = FakeProviderForBackendV2()
@@ -140,3 +141,13 @@ def test_defaults_to_dict(self, backend):
                 self.assertGreater(i, 1e6)
         else:
             self.skipTest("Backend %s does not have defaults" % backend)
+
+    def test_delay_circuit(self):
+        backend = FakeMumbaiV2()
+        qc = QuantumCircuit(2)
+        qc.delay(502, 0, unit="ns")
+        qc.x(1)
+        qc.delay(250, 1, unit="ns")
+        qc.measure_all()
+        res = transpile(qc, backend)
+        self.assertIn("delay", res.count_ops())