Expose ability to go from USD stage to MjSpec.

PiperOrigin-RevId: 776184388
Change-Id: I0325b347c9896183d148a196897e1e5d0c4bbde2

test/experimental/CMakeLists.txt

@@ -12,7 +12,22 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-if(MUJOCO_BUILD_USD_PLUGINS AND MUJOCO_USD_TARGET STREQUAL "USD")
+# Only support testing when building against a standalone version of USD.
+if(MUJOCO_WITH_USD AND USD_DIR)
+  find_package(pxr REQUIRED)
+
+  add_library(usd_test_utils STATIC usd/test_utils.h usd/test_utils.cc)
+  target_include_directories(usd_test_utils PUBLIC ${MUJOCO_TEST_INCLUDE})
+  target_compile_definitions(usd_test_utils PUBLIC MJSTATIC)
+  target_link_libraries(
+    usd_test_utils
+    PUBLIC usd
+           tf
+           gtest
+           gmock
+           mujoco
+  )
+
   add_subdirectory(usd/plugins/mjcf)
 endif()
 

test/experimental/usd/plugins/mjcf/CMakeLists.txt

@@ -12,19 +12,13 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-find_package(pxr REQUIRED)
-
-add_library(usd_fixture STATIC fixture.h fixture.cc)
-target_include_directories(usd_fixture PUBLIC ${MUJOCO_TEST_INCLUDE})
-target_compile_definitions(usd_fixture PUBLIC MJSTATIC)
-
-target_link_libraries(
-  usd_fixture
-  PUBLIC usd
-         tf
-         gtest
-         gmock
-         mujoco
-)
-
-mujoco_test(mjcf_file_format_test ADDITIONAL_LINK_LIBRARIES usd tf usdGeom usdImaging usdPhysics usdShade usd_fixture)
+mujoco_test(mjcf_file_format_test ADDITIONAL_LINK_LIBRARIES
+  usd
+  tf
+  usdGeom
+  usdImaging
+  usdPhysics
+  usdShade
+  usd_test_utils
+  mjcPhysics
+  )