Add elasticity plugins to xml_native_writer_test. Fixes #961.

PiperOrigin-RevId: 545454207
Change-Id: I4e93499eaa53e5bc8c8afa682986657cef3ac20f

src/xml/xml_native_writer.cc

@@ -1390,7 +1390,7 @@ void mjXWriter::Body(XMLElement* elem, mjCBody* body) {
 
   // write plugin
   if (body->is_plugin) {
-    OnePlugin(elem, body);
+    OnePlugin(InsertEnd(elem, "plugin"), body);
   }
 
   // write child bodies recursively

test/fixture.h

@@ -19,6 +19,7 @@
 #include <absl/strings/string_view.h>
 #include <mujoco/mjdata.h>
 #include <mujoco/mjmodel.h>
+#include <mujoco/mujoco.h>
 
 namespace mujoco {
 
@@ -65,5 +66,29 @@ const std::string SaveAndReadXml(const mjModel* model);
 std::vector<mjtNum> GetCtrlNoise(const mjModel* m, int nsteps,
                                  mjtNum ctrlnoise = 0.01);
 
+// Installs elasticity plugins
+// TODO(quaglino): load all plugins with a macro
+class PluginTest : public MujocoTest {
+ public:
+  // load plugin library
+  PluginTest() : MujocoTest() {
+    #if defined(_WIN32) || defined(__CYGWIN__)
+      mj_loadPluginLibrary((
+        std::string(std::getenv("MUJOCO_PLUGIN_DIR")) +
+        std::string("\\elasticity.dll")).c_str());
+    #else
+      #if defined(__APPLE__)
+        mj_loadPluginLibrary((
+          std::string(std::getenv("MUJOCO_PLUGIN_DIR")) +
+          std::string("/libelasticity.dylib")).c_str());
+      #else
+        mj_loadPluginLibrary((
+          std::string(std::getenv("MUJOCO_PLUGIN_DIR")) +
+          std::string("/libelasticity.so")).c_str());
+      #endif
+    #endif
+  }
+};
+
 }  // namespace mujoco
 #endif  // MUJOCO_TEST_FIXTURE_H_

test/plugin/elasticity/elasticity_test.cc

@@ -29,28 +29,6 @@
 namespace mujoco {
 namespace {
 
-class PluginTest : public MujocoTest {
- public:
-  // load plugin library
-  PluginTest() : MujocoTest() {
-    #if defined(_WIN32) || defined(__CYGWIN__)
-      mj_loadPluginLibrary((
-        std::string(std::getenv("MUJOCO_PLUGIN_DIR")) +
-        std::string("\\elasticity.dll")).c_str());
-    #else
-      #if defined(__APPLE__)
-        mj_loadPluginLibrary((
-          std::string(std::getenv("MUJOCO_PLUGIN_DIR")) +
-          std::string("/libelasticity.dylib")).c_str());
-      #else
-        mj_loadPluginLibrary((
-          std::string(std::getenv("MUJOCO_PLUGIN_DIR")) +
-          std::string("/libelasticity.so")).c_str());
-      #endif
-    #endif
-  }
-};
-
 // -------------------------------- solid -----------------------------------
 TEST_F(PluginTest, ElasticEnergy) {
   static constexpr char cantilever_xml[] = R"(

test/xml/CMakeLists.txt

@@ -18,7 +18,12 @@ target_link_libraries(xml_api_test fixture gmock)
 mujoco_test(xml_native_reader_test)
 target_link_libraries(xml_native_reader_test fixture gmock)
 
-mujoco_test(xml_native_writer_test)
+mujoco_test(
+  xml_native_writer_test
+  PROPERTIES
+  ENVIRONMENT
+  "MUJOCO_PLUGIN_DIR=$<TARGET_FILE_DIR:elasticity>"
+)
 target_link_libraries(
   xml_native_writer_test
   fixture

test/xml/xml_native_writer_test.cc

@@ -14,6 +14,7 @@
 
 // Tests for xml/xml_native_writer.cc.
 
+#include <type_traits>
 #if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
 #include <unistd.h>
 #endif
@@ -959,17 +960,23 @@ static constexpr int kFieldSize = 500;
 // The maximum spacing between a normalised floating point number x and an
 // adjacent normalised number is 2 epsilon |x|; a factor 10 is added accounting
 // for losses during non-idempotent operations such as vector normalizations.
-template<typename T = mjtNum> T Compare(T val1, T val2) {
-  T error;
+template <typename T>
+auto Compare(T val1, T val2) {
+  using ReturnType =
+      std::conditional_t<std::is_same_v<T, float>, float, double>;
+  ReturnType error;
   if (mju_abs(val1) <= 1 || mju_abs(val2) <= 1) {
-      // Asbolute precision for small numbers
+      // Absolute precision for small numbers
       error = mju_abs(val1-val2);
   } else {
     // Relative precision for larger numbers
-    T magnitude = mju_max(mju_abs(val1), mju_abs(val2));
+    ReturnType magnitude = mju_abs(val1) + mju_abs(val2);
     error = mju_abs(val1/magnitude - val2/magnitude) / magnitude;
   }
-  return error < 2*10*std::numeric_limits<T>::epsilon() ? 0 : error;
+  ReturnType safety_factor = 10;
+  return error < safety_factor * std::numeric_limits<ReturnType>::epsilon()
+             ? 0
+             : error;
 }
 
 mjtNum CompareModel(const mjModel* m1, const mjModel* m2,
@@ -1015,7 +1022,7 @@ mjtNum CompareModel(const mjModel* m1, const mjModel* m2,
   return maxdif;
 }
 
-TEST_F(XMLWriterTest, WriteReadCompare) {
+TEST_F(PluginTest, WriteReadCompare) {
   FullFloatPrecision increase_precision;
   // Loop over all xml files in data
   std::vector<std::string> paths = {GetTestDataFilePath("."),
@@ -1028,7 +1035,7 @@ TEST_F(XMLWriterTest, WriteReadCompare) {
 
         // if file is meant to fail, skip it
         if (absl::StrContains(p.path().string(), "malformed_") ||
-            absl::StrContains(p.path().string(), "plugin")) {
+            absl::StrContains(p.path().string(), "touch_grid")) {
           continue;
         }
 
@@ -1051,12 +1058,17 @@ TEST_F(XMLWriterTest, WriteReadCompare) {
           // if failing because assets are missing, accept the test
           ASSERT_THAT(error.data(), HasSubstr("file")) << error.data();
         } else {
+          // for a particularly difficult example, relax the tolerance
+          mjtNum tol =
+              absl::StrContains(p.path().string(), "belt.xml") ? 1e-13 : 0;
+
           // compare and delete
-        char field[kFieldSize] = "";
-        mjtNum result = CompareModel(m, mtemp, field);
-        EXPECT_LE(result, 0) << "Loaded and saved models are different!\n"
-                             << "Affected file " << p.path().string() << '\n'
-                             << "Different field: " << field << '\n';
+          char field[kFieldSize] = "";
+          mjtNum result = CompareModel(m, mtemp, field);
+          EXPECT_LE(result, tol)
+              << "Loaded and saved models are different!\n"
+              << "Affected file " << p.path().string() << '\n'
+              << "Different field: " << field << '\n';
           mj_deleteModel(mtemp);
         }