TST: implement parametrized test for motor coordinates.

Author: phmbressan

tests/conftest.py

@@ -111,16 +111,10 @@ def cesaroni_m1670():  # old name: solid_motor
 
 
 @pytest.fixture
-def calisto(cesaroni_m1670):  # old name: rocket
+def calisto_motorless():
     """Create a simple object of the Rocket class to be used in the tests. This
-    is the same rocket that has been used in the getting started guide for
-    years. The Calisto rocket is the Projeto Jupiter's project launched at the
-    2019 Spaceport America Cup.
-
-    Parameters
-    ----------
-    cesaroni_m1670 : rocketpy.SolidMotor
-        An object of the SolidMotor class. This is a pytest fixture too.
+    is the same rocket that has been used in the getting started guide for years
+    but without a motor.
 
     Returns
     -------
@@ -136,60 +130,71 @@ def calisto(cesaroni_m1670):  # old name: rocket
         center_of_mass_without_motor=0,
         coordinate_system_orientation="tail_to_nose",
     )
+    return calisto
+
+
+@pytest.fixture
+def calisto(calisto_motorless, cesaroni_m1670):  # old name: rocket
+    """Create a simple object of the Rocket class to be used in the tests. This
+    is the same rocket that has been used in the getting started guide for
+    years. The Calisto rocket is the Projeto Jupiter's project launched at the
+    2019 Spaceport America Cup.
+
+    Parameters
+    ----------
+    calisto_motorless : rocketpy.Rocket
+        An object of the Rocket class. This is a pytest fixture too.
+    cesaroni_m1670 : rocketpy.SolidMotor
+        An object of the SolidMotor class. This is a pytest fixture too.
+
+    Returns
+    -------
+    rocketpy.Rocket
+        A simple object of the Rocket class
+    """
+    calisto = calisto_motorless
     calisto.add_motor(cesaroni_m1670, position=-1.373)
     return calisto
 
 
 @pytest.fixture
-def calisto_liquid_modded(liquid_motor):
+def calisto_liquid_modded(calisto_motorless, liquid_motor):
     """Create a simple object of the Rocket class to be used in the tests. This
     is an example of the Calisto rocket with a liquid motor.
 
     Parameters
     ----------
+    calisto_motorless : rocketpy.Rocket
+        An object of the Rocket class. This is a pytest fixture too.
     liquid_motor : rocketpy.LiquidMotor
 
     Returns
     -------
     rocketpy.Rocket
         A simple object of the Rocket class
     """
-    calisto = Rocket(
-        radius=0.0635,
-        mass=14.426,
-        inertia=(6.321, 6.321, 0.034),
-        power_off_drag="data/calisto/powerOffDragCurve.csv",
-        power_on_drag="data/calisto/powerOnDragCurve.csv",
-        center_of_mass_without_motor=0,
-        coordinate_system_orientation="tail_to_nose",
-    )
+    calisto = calisto_motorless
     calisto.add_motor(liquid_motor, position=-1.373)
     return calisto
 
 
 @pytest.fixture
-def calisto_hybrid_modded(hybrid_motor):
+def calisto_hybrid_modded(calisto_motorless, hybrid_motor):
     """Create a simple object of the Rocket class to be used in the tests. This
     is an example of the Calisto rocket with a hybrid motor.
 
     Parameters
     ----------
+    calisto_motorless : rocketpy.Rocket
+        An object of the Rocket class. This is a pytest fixture too.
     hybrid_motor : rocketpy.HybridMotor
 
     Returns
     -------
     rocketpy.Rocket
         A simple object of the Rocket class
     """
-    calisto = Rocket(
-        radius=0.0635,
-        mass=14.426,
-        inertia=(6.321, 6.321, 0.034),
-        power_off_drag="data/calisto/powerOffDragCurve.csv",
-        power_on_drag="data/calisto/powerOnDragCurve.csv",
-        center_of_mass_without_motor=0,
-        coordinate_system_orientation="tail_to_nose",
-    )
+    calisto = calisto_motorless
     calisto.add_motor(hybrid_motor, position=-1.373)
     return calisto
 

tests/test_rocket.py

@@ -379,6 +379,56 @@ def test_add_fins_assert_cp_cm_plus_fins(calisto, dimensionless_calisto, m):
     )
 
 
+@pytest.mark.parametrize(
+    """cdm_position, grain_cm_position, nozzle_position, coord_direction, 
+    motor_position, expected_motor_cdm, expected_motor_cpp""",
+    [
+        (0.317, 0.397, 0, "nozzle_to_combustion_chamber", -1.373, -1.056, -0.976),
+        (0, 0.08, -0.317, "nozzle_to_combustion_chamber", -1, -1, -0.92),
+        (-0.317, -0.397, 0, "combustion_chamber_to_nozzle", -1.373, -1.056, -0.976),
+        (0, -0.08, 0.317, "combustion_chamber_to_nozzle", -1, -1, -0.92),
+        (1.317, 1.397, 1, "nozzle_to_combustion_chamber", -2.373, -1.056, -0.976),
+    ],
+)
+def test_add_motor_coordinates(
+    calisto_motorless,
+    cdm_position,
+    grain_cm_position,
+    nozzle_position,
+    coord_direction,
+    motor_position,
+    expected_motor_cdm,
+    expected_motor_cpp,
+):
+    example_motor = SolidMotor(
+        thrust_source="data/motors/Cesaroni_M1670.eng",
+        burn_time=3.9,
+        dry_mass=0,
+        dry_inertia=(0, 0, 0),
+        center_of_dry_mass_position=cdm_position,
+        nozzle_position=nozzle_position,
+        grain_number=5,
+        grain_density=1815,
+        nozzle_radius=33 / 1000,
+        throat_radius=11 / 1000,
+        grain_separation=5 / 1000,
+        grain_outer_radius=33 / 1000,
+        grain_initial_height=120 / 1000,
+        grains_center_of_mass_position=grain_cm_position,
+        grain_initial_inner_radius=15 / 1000,
+        interpolation_method="linear",
+        coordinate_system_orientation=coord_direction,
+    )
+    calisto = calisto_motorless
+    calisto.add_motor(example_motor, position=motor_position)
+
+    calculated_motor_cdm = calisto.motor_center_of_dry_mass_position
+    calculated_motor_cpp = calisto.center_of_propellant_position
+
+    assert pytest.approx(expected_motor_cdm) == calculated_motor_cdm
+    assert pytest.approx(expected_motor_cpp) == calculated_motor_cpp(0)
+
+
 def test_add_cm_eccentricity_assert_properties_set(calisto):
     calisto.add_cm_eccentricity(x=4, y=5)