TST: solid_motor.py testing refactors

tests/conftest.py

@@ -110,6 +110,41 @@ def cesaroni_m1670():  # old name: solid_motor
     return example_motor
 
 
+@pytest.fixture
+def cesaroni_m1670_shifted():  # old name: solid_motor
+    """Create a simple object of the SolidMotor class to be used in the tests.
+    This is the same motor that has been used in the getting started guide for
+    years. The difference relies in the thrust_source, which was shifted for
+    testing purposes.
+
+    Returns
+    -------
+    rocketpy.SolidMotor
+        A simple object of the SolidMotor class
+    """
+    example_motor = SolidMotor(
+        thrust_source="tests/fixtures/motor/Cesaroni_M1670_shifted.eng",
+        burn_time=3.9,
+        dry_mass=1.815,
+        dry_inertia=(0.125, 0.125, 0.002),
+        center_of_dry_mass_position=0.317,
+        nozzle_position=0,
+        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=0.397,
+        grain_initial_inner_radius=15 / 1000,
+        interpolation_method="linear",
+        coordinate_system_orientation="nozzle_to_combustion_chamber",
+        reshape_thrust_curve=(5, 3000),
+    )
+    return example_motor
+
+
 @pytest.fixture
 def calisto_motorless():
     """Create a simple object of the Rocket class to be used in the tests. This

tests/test_function.py

@@ -233,21 +233,29 @@ def test_integral_spline_interpolation(request, func, a, b):
     )
 
 
-def test_differentiate():
-    """Tests the differentiation method of the Function class.
-    Both with respect to return instances and expected behaviour.
-    """
-    func = Function(1)
-    assert isinstance(func.differentiate(0), float)
-    assert np.isclose(func.differentiate(5), 0)
-
-    func_x = Function(lambda x: x)
-    assert isinstance(func_x.differentiate(0), float)
-    assert np.isclose(func_x.differentiate(0), 1)
+@pytest.mark.parametrize(
+    "func_input, derivative_input, expected_derivative",
+    [
+        (1, 0, 0),  # Test case 1: Function(1)
+        (lambda x: x, 0, 1),  # Test case 2: Function(lambda x: x)
+        (lambda x: x**2, 1, 2),  # Test case 3: Function(lambda x: x**2)
+    ],
+)
+def test_differentiate(func_input, derivative_input, expected_derivative):
+    """Test the differentiate method of the Function class.
 
-    f_square = Function(lambda x: x**2)
-    assert isinstance(f_square.differentiate(1), float)
-    assert np.isclose(f_square.differentiate(1), 2)
+    Parameters
+    ----------
+    func_input : function
+        A function object created from a list of values.
+    derivative_input : int
+        Point at which to differentiate.
+    expected_derivative : float
+        Expected value of the derivative.
+    """
+    func = Function(func_input)
+    assert isinstance(func.differentiate(derivative_input), float)
+    assert np.isclose(func.differentiate(derivative_input), expected_derivative)
 
 
 def test_get_value():

tests/test_solidmotor.py

@@ -4,7 +4,7 @@
 import numpy as np
 import pytest
 
-from rocketpy import SolidMotor
+from rocketpy import Function, SolidMotor
 
 burn_time = 3.9
 grain_number = 5
@@ -15,6 +15,8 @@
 grain_initial_height = 120 / 1000
 nozzle_radius = 33 / 1000
 throat_radius = 11 / 1000
+grain_vol = 0.12 * (np.pi * (0.033**2 - 0.015**2))
+grain_mass = grain_vol * 1815 * 5
 
 
 @patch("matplotlib.pyplot.show")
@@ -170,6 +172,14 @@ def test_evaluate_inertia_33_asserts_extreme_values(cesaroni_m1670):
 
 
 def tests_import_eng_asserts_read_values_correctly(cesaroni_m1670):
+    """Tests the import_eng method. It checks whether the import operation
+    extracts the values correctly.
+
+    Parameters
+    ----------
+    cesaroni_m1670_shifted : rocketpy.SolidMotor
+        The SolidMotor object to be used in the tests.
+    """
     comments, description, data_points = cesaroni_m1670.import_eng(
         "tests/fixtures/motor/Cesaroni_M1670.eng"
     )
@@ -197,8 +207,14 @@ def tests_import_eng_asserts_read_values_correctly(cesaroni_m1670):
 
 
 def tests_export_eng_asserts_exported_values_correct(cesaroni_m1670):
-    grain_vol = 0.12 * (np.pi * (0.033**2 - 0.015**2))
-    grain_mass = grain_vol * 1815 * 5
+    """Tests the export_eng method. It checks whether the exported values
+    of the thrust curve still match data_points.
+
+    Parameters
+    ----------
+    cesaroni_m1670_shifted : rocketpy.SolidMotor
+        The SolidMotor object to be used in the tests.
+    """
 
     cesaroni_m1670.export_eng(
         file_name="tests/cesaroni_m1670.eng", motor_name="test_motor"
@@ -239,31 +255,30 @@ def tests_export_eng_asserts_exported_values_correct(cesaroni_m1670):
     ]
 
 
-def test_reshape_thrust_curve_asserts_resultant_thrust_curve_correct():
-    example_motor = SolidMotor(
-        thrust_source="tests/fixtures/motor/Cesaroni_M1670_shifted.eng",
-        burn_time=burn_time,
-        dry_mass=1.815,
-        dry_inertia=(0.125, 0.125, 0.002),
-        center_of_dry_mass_position=0.317,
-        nozzle_position=0,
-        grain_number=grain_number,
-        grain_density=grain_density,
-        nozzle_radius=nozzle_radius,
-        throat_radius=throat_radius,
-        grain_separation=grain_separation,
-        grain_outer_radius=grain_outer_radius,
-        grain_initial_height=grain_initial_height,
-        grains_center_of_mass_position=0.397,
-        grain_initial_inner_radius=grain_initial_inner_radius,
-        interpolation_method="linear",
-        coordinate_system_orientation="nozzle_to_combustion_chamber",
-        reshape_thrust_curve=(5, 3000),
+@pytest.mark.parametrize("tuple_parametric", [(5, 3000)])
+def test_reshape_thrust_curve_asserts_resultant_thrust_curve_correct(
+    cesaroni_m1670_shifted, tuple_parametric, linear_func
+):
+    """Tests the reshape_thrust_curve. It checks whether the resultant
+    thrust curve is correct when the user passes a certain tuple to the
+    reshape_thrust_curve attribute. Also checking for the correct return
+    data type.
+
+    Parameters
+    ----------
+    cesaroni_m1670_shifted : rocketpy.SolidMotor
+        The SolidMotor object to be used in the tests.
+    tuple_parametric : tuple
+        Tuple passed to the reshape_thrust_curve method.
+    """
+
+    assert isinstance(
+        cesaroni_m1670_shifted.reshape_thrust_curve(linear_func, 1, 3000), Function
     )
+    thrust_reshaped = cesaroni_m1670_shifted.thrust.get_source()
 
-    thrust_reshaped = example_motor.thrust.get_source()
-    assert thrust_reshaped[1][0] == 0.155 * (5 / 4)
-    assert thrust_reshaped[-1][0] == 5
+    assert thrust_reshaped[1][0] == 0.155 * (tuple_parametric[0] / 4)
+    assert thrust_reshaped[-1][0] == tuple_parametric[0]
 
-    assert thrust_reshaped[1][1] == 100 * (3000 / 7539.1875)
-    assert thrust_reshaped[7][1] == 2034 * (3000 / 7539.1875)
+    assert thrust_reshaped[1][1] == 100 * (tuple_parametric[1] / 7539.1875)
+    assert thrust_reshaped[7][1] == 2034 * (tuple_parametric[1] / 7539.1875)