Fix error in statistics and adjust tests

Author: Takishima

projectq/cengines/_gate_manager.py

@@ -862,8 +862,8 @@ def _add_to_execute_list(node):
                         self._stats['simul_exec'][-1] += 1
                         key = frozenset((mapping[node.logical_id0],
                                          mapping[node.logical_id1]))
-                        self._stats['2qubit_gates_loc'][key] = self._stats.get(
-                            node.logical_ids, 0) + 1
+                        self._stats['2qubit_gates_loc'][key] \
+                            = self._stats['2qubit_gates_loc'].get(key, 0) + 1
                         for cmd in node.compatible_successor_cmds:
                             if len([
                                     qubit.id for qureg in cmd.all_qubits

projectq/cengines/_gate_manager_test.py

@@ -972,6 +972,9 @@ def test_qubit_manager_str():
         Command(engine=None, gate=X, qubits=([qb[1]], )),
         Command(engine=None, gate=X, qubits=([qb[4]], ), controls=[qb[5]]),
         Command(engine=None, gate=X, qubits=([qb[5]], ), controls=[qb[4]]),
+        Command(engine=None, gate=X, qubits=([qb[3]], ), controls=[qb[4]]),
+        Command(engine=None, gate=X, qubits=([qb[5]], ), controls=[qb[4]]),
+        Command(engine=None, gate=X, qubits=([qb[3]], ), controls=[qb[4]]),
         Command(engine=None, gate=X, qubits=([qb[5]], ), controls=[qb[6]]),
         Command(engine=None, gate=X, qubits=([qb[6]], ), controls=[qb[7]]),
         Command(engine=None, gate=X, qubits=([qb[7]], ), controls=[qb[8]]),
@@ -1008,5 +1011,8 @@ def test_qubit_manager_str():
         if m:
             num_of_2qubit_gates += int(m.group(1))
 
+    edge34_count = int(re.search(r'\s+\[3, 4\]:\s+([0-9]+)',
+                                 str_repr).group(1))
     assert num_of_2qubit_gates == num_of_2qubit_gates_ref
-    assert str_repr.count("[4, 5]:  2") == 1
+    assert edge34_count > 1
+    assert str_repr.count("[4, 5]:  3") == 1