optimization_level=0 without coupling map (#2460) (#2509)

* optimization_level=0 without coupling map

* lean fix

* add test

* style

qiskit/transpiler/preset_passmanagers/level0.py

@@ -104,6 +104,5 @@ def _direction_condition(property_set):
         # pm0.append(_direction_check)  # TODO
         pm0.append(_direction, condition=_direction_condition)
     pm0.append(_reset)
-    pm0.append(_direction)
 
     return pm0

test/python/transpiler/test_preset_passmanagers.py

@@ -0,0 +1,34 @@
+# -*- coding: utf-8 -*-
+
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2017, 2019.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+"""Tests preset pass manager functionalities"""
+
+from qiskit.test import QiskitTestCase
+from qiskit.compiler import transpile
+from qiskit import QuantumCircuit, QuantumRegister
+
+
+class TestPresetPassManager(QiskitTestCase):
+    """Test preset passmanagers work as expected."""
+
+    def test_no_coupling_map(self):
+        """Test that coupling_map can be None"""
+        q = QuantumRegister(2, name='q')
+        test = QuantumCircuit(q)
+        test.cz(q[0], q[1])
+        for level in [0, 1, 2, 3]:
+            with self.subTest(level=level):
+                test2 = transpile(test, basis_gates=['u1', 'u2', 'u3', 'cx'],
+                                  optimization_level=level)
+                self.assertIsInstance(test2, QuantumCircuit)