Fix lint errors

qiskit/transpiler/passes/optimization/inverse_cancellation.py

@@ -46,7 +46,7 @@ def __init__(self, gates_to_cancel: List[Union[Gate, Tuple[Gate, Gate]]]):
                     raise TranspilerError(
                         "Too many or too few inputs: {}. Only two are allowed.".format(gates)
                     )
-                elif gates[0] != gates[1].inverse():
+                if gates[0] != gates[1].inverse():
                     raise TranspilerError(
                         "Gate {} and {} are not inverse.".format(gates[0].name, gates[1].name)
                     )

test/python/transpiler/test_inverse_cancellation.py

@@ -25,6 +25,8 @@
 
 
 class TestInverseCancellation(QiskitTestCase):
+    """Test the InverseCancellation transpiler pass."""
+
     def test_basic_self_inverse(self):
         """Test that a single self-inverse gate as input can be cancelled."""
         qc = QuantumCircuit(2, 2)
@@ -83,14 +85,6 @@ def test_non_inverse_do_not_cancel(self):
         self.assertIn("rx", gates_after)
         self.assertEqual(gates_after["rx"], 2)
 
-    def test_non_inverse_raise_error(self):
-        """Test that non-inverse gate inputs raise an error."""
-        qc = QuantumCircuit(2, 2)
-        qc.rx(np.pi / 2, 0)
-        qc.rx(np.pi / 4, 0)
-        with self.assertRaises(TranspilerError):
-            pass_ = InverseCancellation([RXGate(0.5)])
-
     def test_non_consecutive_gates(self):
         """Test that only consecutive gates cancel."""
         qc = QuantumCircuit(2, 2)
@@ -131,21 +125,29 @@ def test_self_inverse_on_different_qubits(self):
         gates_after = new_circ.count_ops()
         self.assertNotIn("h", gates_after)
 
+    def test_non_inverse_raise_error(self):
+        """Test that non-inverse gate inputs raise an error."""
+        qc = QuantumCircuit(2, 2)
+        qc.rx(np.pi / 2, 0)
+        qc.rx(np.pi / 4, 0)
+        with self.assertRaises(TranspilerError):
+            InverseCancellation([RXGate(0.5)])
+
     def test_non_gate_inverse_raise_error(self):
         """Test that non-inverse gate inputs raise an error."""
         qc = QuantumCircuit(2, 2)
         qc.rx(np.pi / 4, 0)
         qc.rx(np.pi / 4, 0)
         with self.assertRaises(TranspilerError):
-            pass_ = InverseCancellation([(RXGate(np.pi / 4))])
+            InverseCancellation([(RXGate(np.pi / 4))])
 
     def test_string_gate_error(self):
         """Test that when gate is passed as a string an error is raised."""
         qc = QuantumCircuit(2, 2)
         qc.h(0)
         qc.h(0)
         with self.assertRaises(TranspilerError):
-            pass_ = InverseCancellation(["h"])
+            InverseCancellation(["h"])
 
     def test_consecutive_self_inverse_h_x_gate(self):
         """Test that only consecutive self-inverse gates cancel."""