Update the tracker used with batch execution

CHANGELOG.md

@@ -8,6 +8,7 @@
   gradients internally.
   [(#156)](https://github.com/PennyLaneAI/pennylane-qiskit/pull/156)
   [(#163)](https://github.com/PennyLaneAI/pennylane-qiskit/pull/163)
+  [(#167)](https://github.com/PennyLaneAI/pennylane-qiskit/pull/167)
 
 ### Breaking changes
 

pennylane_qiskit/qiskit_device.py

@@ -401,6 +401,11 @@ def batch_execute(self, circuits):
         results = []
         for circuit, circuit_obj in zip(circuits, compiled_circuits):
 
+            # Update the tracker
+            if self.tracker.active:
+                self.tracker.update(executions=1, shots=self.shots)
+                self.tracker.record()
+
             if self.backend_name in self._state_backends:
                 self._state = self._get_state(result, experiment=circuit_obj)
 

tests/test_integration.py

@@ -569,3 +569,24 @@ def circuit(x, y):
         # Check that run was called twice: for the partial derivatives and for
         # running the circuit
         assert spy2.call_count == 2
+
+    def test_tracker(self):
+        """Tests the device tracker with batch execution."""
+        dev = qml.device('qiskit.aer', shots=100, wires=3)
+
+        @qml.qnode(dev, diff_method="parameter-shift")
+        def circuit(x):
+            qml.RX(x, wires=0)
+            return qml.expval(qml.PauliZ(0))
+
+        x = tensor(0.1, requires_grad=True)
+
+        with qml.Tracker(dev) as tracker:
+            qml.grad(circuit)(x)
+
+        expected = {'executions': [1, 1, 1],
+                     'shots': [100, 100, 100],
+                     'batches': [1, 1],
+                     'batch_len': [1, 2]}
+
+        assert tracker.history == expected

tests/test_qiskit_device.py

@@ -162,7 +162,8 @@ def test_result(self, device, tol):
         assert np.allclose(res[1], tape2_expected, atol=0)
 
     def test_result_empty_tape(self, device, tol):
-        """Tests that the result has the correct shape and entry types for empty tapes."""
+        """Tests that the result has the correct shape and entry types for
+        empty tapes."""
         dev = device(2)
 
         empty_tape = qml.tape.QuantumTape()