Move test_collidable_point_jacobians to test_api_contact

tests/test_api_contact.py

@@ -68,6 +68,38 @@ def test_contact_kinematics(
     assert W_ṗ_C == pytest.approx(CW_vl_WC)
 
 
+def test_collidable_point_jacobians(
+    jaxsim_models_types: js.model.JaxSimModel,
+    velocity_representation: VelRepr,
+    prng_key: jax.Array,
+):
+
+    model = jaxsim_models_types
+
+    _, subkey = jax.random.split(prng_key, num=2)
+    data = js.data.random_model_data(
+        model=model, key=subkey, velocity_representation=velocity_representation
+    )
+
+    # =====
+    # Tests
+    # =====
+
+    # Compute the velocity of the collidable points with a RBDA.
+    # This function always returns the linear part of the mixed velocity of the
+    # implicit frame C corresponding to the collidable point.
+    W_ṗ_C = js.contact.collidable_point_velocities(model=model, data=data)
+
+    # Compute the generalized velocity and the free-floating Jacobian of the frame C.
+    ν = data.generalized_velocity
+    CW_J_WC = js.contact.jacobian(model=model, data=data, output_vel_repr=VelRepr.Mixed)
+
+    # Compute the velocity of the collidable points using the Jacobians.
+    v_WC_from_jax = jax.vmap(lambda J, ν: J @ ν, in_axes=(0, None))(CW_J_WC, ν)
+
+    assert W_ṗ_C == pytest.approx(v_WC_from_jax[:, 0:3])
+
+
 def test_contact_jacobian_derivative(
     jaxsim_models_floating_base: js.model.JaxSimModel,
     velocity_representation: VelRepr,