adds test for _controlled_qubit_unitary

tests/test_apply.py

@@ -249,6 +249,23 @@ def test_qubit_unitary(self, init_state, mat, tol):
         expected = mat @ state
         assert np.allclose(res, expected, tol)
 
+    @pytest.mark.parametrize("control_wires", [[0], [1], [0, 1]])
+    @pytest.mark.parametrize("mat", [U, U2])
+    def test_controlled_qubit_unitary(self, init_state, mat, control_wires, tol):
+        """Test ControlledQubitUnitary application"""
+
+        N = int(np.log2(len(mat)))
+        dev = QulacsDevice(N + len(control_wires))
+        state = init_state(N + len(control_wires))
+
+        op = qml.ControlledQubitUnitary(mat, wires=list(range(N, N + len(control_wires) + 1)), control_wires=control_wires)
+        dev.apply([qml.QubitStateVector(state, wires=list(range(N + len(control_wires)))), op])
+        dev._obs_queue = []
+
+        res = dev.state
+        expected = np.kron(np.eye(2 ** N), np.eye(2 ** len(control_wires))) @ np.kron(np.eye(2 ** N), mat) @ state
+        assert np.allclose(res, expected, tol)
+
     def test_invalid_qubit_state_unitary(self):
         """Test that an exception is raised if the
         unitary matrix is the wrong size"""