Missing unit tests for benchmarking circuits (#2366)

* mirror circuits

* randomized benchmarking

* clifford t + ruff

mitiq/benchmarks/tests/test_mirror_circuits.py

@@ -195,6 +195,13 @@ def test_two_qubit_gate_unsupported():
         )
 
 
+def test_two_qubit_gate_bad_probability():
+    with pytest.raises(
+        ValueError, match="two_qubit_gate_prob must be between 0 and 1"
+    ):
+        mirror_circuits.generate_mirror_circuit(1, 2.0, nx.complete_graph(2))
+
+
 def test_deterministic_correct_bitstrings():
     """For a fixed seed, correct bitstrings should be deterministic."""
     expected_correct_bitstrings = (

mitiq/benchmarks/tests/test_randomized_benchmarking.py

@@ -41,3 +41,11 @@ def test_rb_conversion(n_qubits, return_type):
         )
         for qc in circuits:
             assert return_type in qc.__module__
+
+
+def test_bad_n_qubits():
+    with pytest.raises(
+        ValueError, match="Only generates RB circuits on one or two "
+    ):
+        for trials in [2, 3]:
+            generate_rb_circuits(n_qubits=4, num_cliffords=10, trials=trials)

mitiq/benchmarks/tests/test_randomized_clifford_t_circuit.py

@@ -51,3 +51,21 @@ def test_conversion(return_type):
         return_type=return_type,
     )
     assert return_type in circuit.__module__
+
+
+@pytest.mark.parametrize(
+    "test_num_qubits, test_num_twoq_cliffords, error_msg",
+    [
+        (0, 2, "Cannot prepare a circuit with"),
+        (1, 2, "Need more than 2 qubits for two-qubit Clifford gates."),
+    ],
+)
+def test_invalid_input(test_num_qubits, test_num_twoq_cliffords, error_msg):
+    """Ensures error raised as expected."""
+    with pytest.raises(ValueError, match=error_msg):
+        generate_random_clifford_t_circuit(
+            num_qubits=test_num_qubits,
+            num_oneq_cliffords=2,
+            num_twoq_cliffords=test_num_twoq_cliffords,
+            num_t_gates=2,
+        )