Fix bug with mimic joint namespacing implementation

pkgs/node_helpers/node_helpers/urdfs/loading.py

@@ -11,6 +11,7 @@
 _CHILD_TAG = "child"
 _NAME_KEY = "name"
 _LINK_KEY = "link"
+_JOINT_KEY = "joint"
 _MIMIC_TAG = "mimic"
 
 
@@ -138,6 +139,6 @@ def prepend_namespace(urdf_str: str, namespace: str) -> str:
         elif node.tag == _MIMIC_TAG:
             node.set(
                 "joint",
-                NAMESPACE_FMT.format(namespace=namespace, name=node.get(_NAME_KEY)),
+                NAMESPACE_FMT.format(namespace=namespace, name=node.get(_JOINT_KEY)),
             )
     return ElementTree.tostring(urdf, encoding="unicode")

pkgs/node_helpers/node_helpers_test/unit/urdfs/test_loading.py

@@ -118,3 +118,15 @@ def test_prepend_namespace() -> None:
             )
         )
         assert len(expected_changes) == len(actual_changes)
+
+
+def test_mimics_are_prepended() -> None:
+    """Validate that 'mimic' style joints are prepended with the namespace as well."""
+
+    urdf_text: str = GENERIC_URDF.read_text()
+    namespace = "cool_namespace"
+
+    mimic_joint = "clamp1-joint"
+    assert f"{namespace}.{mimic_joint}" not in urdf_text
+    modified = urdf_helpers.prepend_namespace(urdf_text, namespace=namespace)
+    assert modified.count(f'mimic joint="{namespace}.{mimic_joint}"') == 1