chore(lint): fix the ruff findings in Dynamics.py and RobotProto.py, except module names

src/roboticstoolbox/robot/Dynamics.py

@@ -30,7 +30,8 @@
 from __future__ import annotations
 
 import warnings
-from typing import Any, Callable, NamedTuple
+from collections.abc import Callable
+from typing import Any, NamedTuple
 from typing import Literal as L
 
 import numpy as np
@@ -207,10 +208,10 @@ def fdyn(
         T: float,
         q0: ArrayLike,
         Q: Callable[[Any, float, NDArray, NDArray], NDArray] | None = None,
-        Q_args: dict = {},
+        Q_args: dict | None = None,
         qd0: ArrayLike | None = None,
         solver: str = "RK45",
-        solver_args: dict = {},
+        solver_args: dict | None = None,
         dt: float | None = None,
         progress: bool = False,
     ) -> Any:
@@ -320,9 +321,11 @@ def fdyn(
             qd0 = np.zeros((n,))
         else:
             qd0 = getvector(qd0, n)
-        if Q is not None:
-            if not callable(Q):
-                raise ValueError("generalized joint torque function must be callable")
+        if Q is not None and not callable(Q):
+            raise ValueError("generalized joint torque function must be callable")
+        # not a default argument, which would be one dict shared by every call
+        Q_args = {} if Q_args is None else Q_args
+        solver_args = {} if solver_args is None else solver_args
 
         # concatenate q and qd into the initial state vector
         x0 = np.r_[q0, qd0]
@@ -613,7 +616,7 @@ def pay(
 
         return tau
 
-    def payload(self: RobotProto, m: float, p: Any = np.zeros(3)) -> None:
+    def payload(self: RobotProto, m: float, p: ArrayLike | None = None) -> None:
         """
         Add a payload to the end-effector
 
@@ -661,7 +664,7 @@ def payload(self: RobotProto, m: float, p: Any = np.zeros(3)) -> None:
             link.I = I0.copy()
             return
 
-        p = getvector(p, 3)
+        p = np.zeros(3) if p is None else getvector(p, 3)
         mc = m0 + m
         rc = (m0 * r0 + m * p) / mc
 
@@ -704,8 +707,8 @@ def jointdynamics(self: RobotProto, q: Any, qd: Any = None) -> Any:
         tf = []
         for j, link in enumerate(self.links):
             # compute inertia for this joint
-            zero = np.zeros((self.n))
-            qdd = np.zeros((self.n))
+            zero = np.zeros(self.n)
+            qdd = np.zeros(self.n)
             qdd[j] = 1
             M = self.rne(q, zero, qdd, gravity=[0, 0, 0])
             J = link.Jm + M[j] / abs(link.G) ** 2

src/roboticstoolbox/robot/RobotProto.py

@@ -1,4 +1,5 @@
-from typing import Callable, Literal
+from collections.abc import Callable
+from typing import Literal
 
 from spatialmath import SE3
 from typing_extensions import Protocol, Self

tests/test_dynamics_defaults.py

@@ -0,0 +1,48 @@
+"""
+Default arguments of the dynamics methods are None, not a mutable object that is
+shared by every call.
+"""
+
+import inspect
+
+import numpy as np
+import numpy.testing as nt
+import pytest
+
+import roboticstoolbox as rtb
+from roboticstoolbox.robot.Dynamics import DynamicsMixin
+
+
+@pytest.mark.parametrize(
+    "method, name",
+    [("fdyn", "Q_args"), ("fdyn", "solver_args"), ("payload", "p")],
+)
+def test_default_is_none(method, name):
+    default = inspect.signature(getattr(DynamicsMixin, method)).parameters[name].default
+    assert default is None
+
+
+def test_payload_without_a_position_is_at_the_origin():
+    puma = rtb.models.DH.Puma560()
+    q = puma.qn
+    puma.payload(2.0)
+    default = puma.gravload(q)
+    puma.payload(0)
+    puma.payload(2.0, [0, 0, 0])
+    nt.assert_allclose(default, puma.gravload(q))
+    puma.payload(0)
+
+
+def test_payload_zero_mass_is_a_no_op():
+    puma = rtb.models.DH.Puma560()
+    before = puma.gravload(puma.qn)
+    puma.payload(0)
+    nt.assert_allclose(puma.gravload(puma.qn), before)
+
+
+def test_fdyn_without_optional_arguments():
+    puma = rtb.models.DH.Puma560()
+    for _ in range(2):
+        t, q, qd = puma.fdyn(0.1, puma.qn, dt=0.05)
+        assert q.shape[1] == 6
+        assert np.all(np.isfinite(q))