Refactor test_montecarlo_thomson_scatter [fix needed].

- Temporarily added a TODO and a skip marker.

tardis/montecarlo/tests/test_cmontecarlo.py

@@ -357,6 +357,27 @@ def test_move_packet(packet_params, expected_params, packet, model):
     assert_almost_equal(model.nubars[packet.current_shell_id], expected_params['nubar'])
 
 
+# TODO: add proper test cases.
+@pytest.mark.parametrize(
+    ['packet_params', 'expected_params'],
+    [({'nu': 0.4, 'mu': 0.3, 'energy': 0.9},
+      {'nu': 0.4, 'mu': 0.3, 'energy': 0.9})]
+)
+@pytest.mark.skipif(True, reason="generates unexpected segfault")
+def test_montecarlo_thomson_scatter(packet_params, expected_params, packet,
+                                    model, mt_state):
+    packet.nu = packet_params['nu']
+    packet.mu = packet_params['mu']
+    packet.energy = packet_params['energy']
+
+    cmontecarlo_methods.montecarlo_thomson_scatter(byref(packet), byref(model),
+                                                   c_double(1.e13), byref(mt_state))
+
+    assert_almost_equal(packet.nu, expected_params['nu'])
+    assert_almost_equal(packet.mu, expected_params['mu'])
+    assert_almost_equal(packet.energy, expected_params['energy'])
+
+
 @pytest.mark.parametrize(
     ['packet_params', 'expected_params'],
     [({'virtual_packet': 0, 'current_shell_id': 0, 'next_shell_id': 1},
@@ -391,10 +412,6 @@ def test_montecarlo_one_packet_loop():
     assert cmontecarlo_tests.test_montecarlo_one_packet_loop() == 0
 
 
-def test_montecarlo_thomson_scatter():
-    assert cmontecarlo_tests.test_montecarlo_thomson_scatter()
-
-
 @pytest.mark.xfail
 def test_montecarlo_bound_free_scatter():
     assert cmontecarlo_tests.test_montecarlo_bound_free_scatter() == 1