Test conditional dag and circuit (#1626)

* Adding conditional converter test

* Linting

* Linting

* Linting

* Linting

test/python/converters/test_circuit_to_dag.py

@@ -0,0 +1,42 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2018, IBM.
+#
+# This source code is licensed under the Apache License, Version 2.0 found in
+# the LICENSE.txt file in the root directory of this source tree.
+
+# pylint: disable=redefined-builtin
+
+"""Tests for the converters."""
+
+import unittest
+
+from qiskit.converters import dag_to_circuit, circuit_to_dag
+from qiskit import QuantumRegister, ClassicalRegister, QuantumCircuit
+
+from ..common import QiskitTestCase
+
+
+class TestCircuitToDag(QiskitTestCase):
+    """Test Circuit to DAG."""
+
+    def test_circuit_and_dag(self):
+        """Check convert to dag and back"""
+        qr = QuantumRegister(3)
+        cr = ClassicalRegister(3)
+        circuit_in = QuantumCircuit(qr, cr)
+        circuit_in.h(qr[0])
+        circuit_in.h(qr[1])
+        circuit_in.measure(qr[0], cr[0])
+        circuit_in.measure(qr[1], cr[1])
+        circuit_in.x(qr[0]).c_if(cr, 0x3)
+        circuit_in.measure(qr[0], cr[0])
+        circuit_in.measure(qr[1], cr[1])
+        circuit_in.measure(qr[2], cr[2])
+        dag = circuit_to_dag(circuit_in)
+        circuit_out = dag_to_circuit(dag)
+        self.assertEqual(circuit_out, circuit_in)
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)