MNT: changed default value of weather_coeff in flight.py and added fixtures to test_flight_3dof.py

Author: aZira371

rocketpy/simulation/flight.py

@@ -492,7 +492,7 @@ def __init__(  # pylint: disable=too-many-arguments,too-many-statements
         equations_of_motion="standard",
         ode_solver="LSODA",
         simulation_mode="6 DOF",
-        weathercock_coeff=1.0,
+        weathercock_coeff=None,
     ):
         """Run a trajectory simulation.
 

tests/unit/simulation/test_flight_3dof.py

@@ -50,9 +50,42 @@ def point_mass_rocket(point_mass_motor):
     return rocket
 
 
-def test_simulation_mode_sets_3dof_with_point_mass_rocket(
-    example_plain_env, point_mass_rocket
-):
+@pytest.fixture
+def flight_weathercock_zero(example_plain_env, point_mass_rocket):
+    """Creates a Flight fixture with weathercock_coeff set to 0.0.
+
+    Returns
+    -------
+    rocketpy.simulation.flight.Flight
+        A Flight object configured for 3-DOF with zero weathercock coefficient.
+    """
+    return Flight(
+        rocket=point_mass_rocket,
+        environment=example_plain_env,
+        rail_length=1,
+        simulation_mode="3 DOF",
+        weathercock_coeff=0.0,
+    )
+
+
+@pytest.fixture
+def flight_3dof(example_plain_env, point_mass_rocket):
+    """Creates a standard 3-DOF Flight fixture with default weathercock_coeff=1.0.
+
+    Returns
+    -------
+    rocketpy.simulation.flight.Flight
+        A Flight object configured for 3-DOF with default weathercock coefficient.
+    """
+    return Flight(
+        rocket=point_mass_rocket,
+        environment=example_plain_env,
+        rail_length=1,
+        simulation_mode="3 DOF",
+    )
+
+
+def test_simulation_mode_sets_3dof_with_point_mass_rocket(flight_3dof):
     """Tests that simulation mode is correctly set to 3 DOF for PointMassRocket.
 
     Parameters
@@ -62,13 +95,7 @@ def test_simulation_mode_sets_3dof_with_point_mass_rocket(
     point_mass_rocket : rocketpy.PointMassRocket
         A point mass rocket fixture for 3-DOF simulation.
     """
-    flight = Flight(
-        rocket=point_mass_rocket,
-        environment=example_plain_env,
-        rail_length=1,
-        simulation_mode="3 DOF",
-    )
-    assert flight.simulation_mode == "3 DOF"
+    assert flight_3dof.simulation_mode == "3 DOF"
 
 
 def test_3dof_simulation_mode_warning(example_plain_env, point_mass_rocket):
@@ -94,9 +121,7 @@ class should emit a UserWarning and automatically switch to 3 DOF mode.
         assert flight.simulation_mode == "3 DOF"
 
 
-def test_u_dot_generalized_3dof_returns_valid_result(
-    example_plain_env, point_mass_rocket
-):
+def test_u_dot_generalized_3dof_returns_valid_result(flight_3dof):
     """Tests that 3-DOF equations of motion return valid derivative results.
 
     Verifies that the u_dot_generalized_3dof method returns a list or numpy
@@ -109,12 +134,7 @@ def test_u_dot_generalized_3dof_returns_valid_result(
     point_mass_rocket : rocketpy.PointMassRocket
         A point mass rocket fixture for 3-DOF simulation.
     """
-    flight = Flight(
-        rocket=point_mass_rocket,
-        environment=example_plain_env,
-        rail_length=1,
-        simulation_mode="3 DOF",
-    )
+    flight = flight_3dof
     u = [0] * 13  # Generalized state vector size
     result = flight.u_dot_generalized_3dof(0, u)
     assert isinstance(result, (list, np.ndarray))
@@ -159,7 +179,7 @@ def test_weathercock_coeff_stored(example_plain_env, point_mass_rocket):
     assert flight.weathercock_coeff == 2.5
 
 
-def test_weathercock_coeff_default(example_plain_env, point_mass_rocket):
+def test_weathercock_coeff_default(flight_3dof):
     """Tests that the default weathercock_coeff is 1.0.
 
     Parameters
@@ -169,16 +189,10 @@ def test_weathercock_coeff_default(example_plain_env, point_mass_rocket):
     point_mass_rocket : rocketpy.PointMassRocket
         A point mass rocket fixture for 3-DOF simulation.
     """
-    flight = Flight(
-        rocket=point_mass_rocket,
-        environment=example_plain_env,
-        rail_length=1,
-        simulation_mode="3 DOF",
-    )
-    assert flight.weathercock_coeff == 1.0
+    assert flight_3dof.weathercock_coeff == 1.0
 
 
-def test_weathercock_zero_gives_fixed_attitude(example_plain_env, point_mass_rocket):
+def test_weathercock_zero_gives_fixed_attitude(flight_weathercock_zero):
     """Tests that weathercock_coeff=0 results in fixed attitude (no quaternion change).
     When weathercock_coeff is 0, the quaternion derivatives should be zero,
     meaning the attitude does not evolve.
@@ -190,13 +204,7 @@ def test_weathercock_zero_gives_fixed_attitude(example_plain_env, point_mass_roc
     point_mass_rocket : rocketpy.PointMassRocket
         A point mass rocket fixture for 3-DOF simulation.
     """
-    flight = Flight(
-        rocket=point_mass_rocket,
-        environment=example_plain_env,
-        rail_length=1,
-        simulation_mode="3 DOF",
-        weathercock_coeff=0.0,
-    )
+    flight = flight_weathercock_zero
     # Create a state vector with non-zero velocity (to have freestream)
     # [x, y, z, vx, vy, vz, e0, e1, e2, e3, w1, w2, w3]
     u = [0, 0, 100, 10, 5, 50, 1, 0, 0, 0, 0, 0, 0]
@@ -207,7 +215,7 @@ def test_weathercock_zero_gives_fixed_attitude(example_plain_env, point_mass_roc
     assert all(abs(ed) < 1e-10 for ed in e_dot), "Quaternion derivatives should be zero"
 
 
-def test_weathercock_nonzero_evolves_attitude(example_plain_env, point_mass_rocket):
+def test_weathercock_nonzero_evolves_attitude(flight_3dof):
     """Tests that non-zero weathercock_coeff causes attitude evolution.
     When the body axis is misaligned with the relative wind and weathercock_coeff
     is positive, the quaternion derivatives should be non-zero.
@@ -219,13 +227,7 @@ def test_weathercock_nonzero_evolves_attitude(example_plain_env, point_mass_rock
     point_mass_rocket : rocketpy.PointMassRocket
         A point mass rocket fixture for 3-DOF simulation.
     """
-    flight = Flight(
-        rocket=point_mass_rocket,
-        environment=example_plain_env,
-        rail_length=1,
-        simulation_mode="3 DOF",
-        weathercock_coeff=1.0,
-    )
+    flight = flight_3dof
     # Create a state with misaligned body axis
     # Body pointing straight up (e0=1, e1=e2=e3=0) but velocity is horizontal
     # [x, y, z, vx, vy, vz, e0, e1, e2, e3, w1, w2, w3]
@@ -238,7 +240,7 @@ def test_weathercock_nonzero_evolves_attitude(example_plain_env, point_mass_rock
     assert e_dot_magnitude > 1e-6, "Quaternion derivatives should be non-zero"
 
 
-def test_weathercock_aligned_no_evolution(example_plain_env, point_mass_rocket):
+def test_weathercock_aligned_no_evolution(flight_3dof):
     """Tests that when body axis is aligned with relative wind, no rotation occurs.
     When the rocket's body z-axis is already aligned with the negative of the
     freestream velocity, the quaternion derivatives should be approximately zero.
@@ -250,13 +252,7 @@ def test_weathercock_aligned_no_evolution(example_plain_env, point_mass_rocket):
     point_mass_rocket : rocketpy.PointMassRocket
         A point mass rocket fixture for 3-DOF simulation.
     """
-    flight = Flight(
-        rocket=point_mass_rocket,
-        environment=example_plain_env,
-        rail_length=1,
-        simulation_mode="3 DOF",
-        weathercock_coeff=1.0,
-    )
+    flight = flight_3dof
     # Body pointing in +x direction (into the wind for vx=50)
     # Quaternion for 90 degree rotation about y-axis uses half-angle:
     # e0=cos(90°/2)=cos(45°), e2=sin(90°/2)=sin(45°)
@@ -273,22 +269,14 @@ def test_weathercock_aligned_no_evolution(example_plain_env, point_mass_rocket):
     )
 
 
-def test_weathercock_anti_aligned_uses_perp_axis_and_evolves(
-    example_plain_env, point_mass_rocket
-):
+def test_weathercock_anti_aligned_uses_perp_axis_and_evolves(flight_3dof):
     """Tests the anti-aligned case where body z-axis is opposite freestream.
 
     This should exercise the branch that selects a perpendicular axis (y-axis)
     when the cross with x-axis is nearly zero, producing a non-zero quaternion
     derivative.
     """
-    flight = Flight(
-        rocket=point_mass_rocket,
-        environment=example_plain_env,
-        rail_length=1,
-        simulation_mode="3 DOF",
-        weathercock_coeff=1.0,
-    )
+    flight = flight_3dof
 
     sqrt2_2 = np.sqrt(2) / 2
     # Build quaternion that makes body z-axis = [-1, 0, 0]