BUG: fix get_controller_observed_variables in the air brakes examples

CHANGELOG.md

@@ -70,6 +70,7 @@ You can install this version by running `pip install rocketpy==1.2.0`
 
 ### Fixed
 
+- BUG: fix `get_controller_observed_variables` in the air brakes examples [#551](https://github.com/RocketPy-Team/RocketPy/pull/551)
 - MNT: small fixes before v1.2 [#550](https://github.com/RocketPy-Team/RocketPy/pull/550)
 - BUG: Elliptical Fins Draw [#548](https://github.com/RocketPy-Team/RocketPy/pull/548)
 - BUG: 3D trajectory plot not labeling axes [#533](https://github.com/RocketPy-Team/RocketPy/pull/533)

docs/user/airbrakes.rst

@@ -401,7 +401,9 @@ Then we can plot the data we want.
 
     time_list, deployment_level_list, drag_coefficient_list = [], [], []
 
-    for time, deployment_level, drag_coefficient in test_flight.get_controller_observed_variables:
+    obs_vars = test_flight.get_controller_observed_variables()
+
+    for time, deployment_level, drag_coefficient in obs_vars:
         time_list.append(time)
         deployment_level_list.append(deployment_level)
         drag_coefficient_list.append(drag_coefficient)

tests/unit/test_flight.py

@@ -250,3 +250,11 @@ def test_export_kml(flight_calisto_robust):
     assert np.allclose(test_flight.latitude[:, 1], lat, atol=1e-3) == True
     assert np.allclose(test_flight.longitude[:, 1], lon, atol=1e-3) == True
     assert np.allclose(test_flight.z[:, 1], z, atol=1e-3) == True
+
+
+def test_get_controller_observed_variables(flight_calisto_air_brakes):
+    """Tests whether the method Flight.get_controller_observed_variables is
+    working as intended."""
+    obs_vars = flight_calisto_air_brakes.get_controller_observed_variables()
+    assert isinstance(obs_vars, list)
+    assert len(obs_vars) == 0