Yield ownership of char[], vector<string>, and vector<byte> to mjSpec in Python bindings.

PiperOrigin-RevId: 681522091
Change-Id: Icb3788d9ef6e914a307531e39ad8171c24f590af

python/mujoco/specs_test.py

@@ -34,9 +34,28 @@ class SpecsTest(absltest.TestCase):
     spec = mujoco.MjSpec()
 
     # Check that euler sequence order is set correctly.
-    self.assertEqual(spec.eulerseq[0], ord('x'))
+    self.assertEqual(spec.eulerseq[0], 'x')
     spec.eulerseq = ['z', 'y', 'x']
-    self.assertEqual(spec.eulerseq[0], ord('z'))
+    self.assertEqual(spec.eulerseq[0], 'z')
+
+    # Change single elements of euler sequence.
+    spec.eulerseq[0] = 'y'
+    spec.eulerseq[1] = 'z'
+    self.assertEqual(spec.eulerseq[0], 'y')
+    self.assertEqual(spec.eulerseq[1], 'z')
+
+    # eulerseq is iterable
+    self.assertEqual('yzx', ''.join(spec.eulerseq))
+
+    # supports `len`
+    self.assertLen(spec.eulerseq, 3)
+
+    # field checks for out-of-bound access on read and on write
+    with self.assertRaises(IndexError):
+      spec.eulerseq[3] = 'x'
+
+    with self.assertRaises(IndexError):
+      spec.eulerseq[-1] = 'x'
 
     # Add a body, check that it has default orientation.
     body = spec.worldbody.add_body()
@@ -50,10 +69,14 @@ class SpecsTest(absltest.TestCase):
     self.assertEqual(body.name, 'baz')
 
     # Change the position of the body and read it back.
-    body.pos = [1, 2, 3]
-    np.testing.assert_array_equal(body.pos, [1, 2, 3])
+    body.pos = [4, 2, 3]
+    np.testing.assert_array_equal(body.pos, [4, 2, 3])
     self.assertEqual(body.pos.shape, (3,))
 
+    # Change single element of position.
+    body.pos[0] = 1
+    np.testing.assert_array_equal(body.pos, [1, 2, 3])
+
     # Change the orientation of the body and read it back.
     body.quat = [0, 1, 0, 0]
     np.testing.assert_array_equal(body.quat, [0, 1, 0, 0])
@@ -147,7 +170,7 @@ class SpecsTest(absltest.TestCase):
     # Add tuple.
     tuple_ = spec.add_tuple(objprm=[2.0, 3.0, 5.0], objname=['obj'])
     np.testing.assert_array_equal(tuple_.objprm, [2.0, 3.0, 5.0])
-    self.assertEqual(tuple_.objname, ['obj'])
+    self.assertEqual(tuple_.objname[0], 'obj')
 
     # Add flex.
     flex = spec.add_flex(friction=[1, 2, 3], texcoord=[1.0, 2.0, 3.0])
@@ -797,5 +820,31 @@ class SpecsTest(absltest.TestCase):
     self.assertEqual(model.stat.meansize, 0.06)
     self.assertEqual(model.vis.quality.shadowsize, 8192)
 
+  def test_assign_list_element(self):
+    spec = mujoco.MjSpec()
+    material = spec.add_material()
+    texture_index = mujoco.mjtTextureRole.mjTEXROLE_RGB
+
+    # Assign a string to a list element.
+    material.textures[texture_index] = 'texture_name'
+    self.assertEqual(material.textures[texture_index], 'texture_name')
+
+    # Assign a complete list
+    material.textures = ['', 'new_name', '', '', '']
+    self.assertEqual(material.textures[texture_index], 'new_name')
+
+    # textures is iterable
+    self.assertEqual('new_name', ''.join(material.textures))
+
+    # supports `len`
+    self.assertLen(material.textures, 5)
+
+    # field checks for out-of-bound access on read and on write
+    with self.assertRaises(IndexError):
+      material.textures[5] = 'x'
+
+    with self.assertRaises(IndexError):
+      material.textures[-1] = 'x'
+
 if __name__ == '__main__':
   absltest.main()