Enable float32 testing for most MuJoCo engine and user tests.

PiperOrigin-RevId: 886697701
Change-Id: I4a96fae03ea18494c3fcef8eb17b3b6f0863e9b7

test/fixture.h

@@ -26,6 +26,7 @@
 #include <string_view>
 #include <vector>
 
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 #include <absl/container/flat_hash_map.h>
 #include <absl/container/flat_hash_set.h>
@@ -39,6 +40,48 @@ MJAPI decltype(mju_user_error)  _mjPRIVATE__get_tls_error_fn();
 
 namespace mujoco {
 
+// Precision-aware GMock matcher. Use instead of DoubleNear/FloatNear.
+// Under double builds, uses double_tol. Under float builds, uses float_tol.
+template <typename T1, typename T2>
+inline auto MjNear(T1 double_tol, T2 float_tol) {
+#ifdef mjUSESINGLE
+  return ::testing::FloatNear(static_cast<float>(float_tol));
+#else
+  return ::testing::DoubleNear(static_cast<double>(double_tol));
+#endif
+}
+
+// Precision-aware GMock matcher (3-arg version).
+// Under double builds, matches near target with double_tol.
+// Under float builds, matches near target with float_tol.
+template <typename T1, typename T2, typename T3>
+inline auto MjNear(T1 target, T2 double_tol, T3 float_tol) {
+#ifdef mjUSESINGLE
+  return ::testing::FloatNear(static_cast<float>(target),
+                              static_cast<float>(float_tol));
+#else
+  return ::testing::DoubleNear(static_cast<double>(target),
+                               static_cast<double>(double_tol));
+#endif
+}
+
+// Precision-aware tolerance for EXPECT_NEAR.
+template <typename T1, typename T2>
+constexpr mjtNum MjTol(T1 double_tol, T2 float_tol) {
+#ifdef mjUSESINGLE
+  return static_cast<mjtNum>(float_tol);
+#else
+  return static_cast<mjtNum>(double_tol);
+#endif
+}
+
+// Precision-aware equality assertion: 4 ULPs in either precision.
+#ifdef mjUSESINGLE
+  #define EXPECT_MJTNUM_EQ(a, b) EXPECT_FLOAT_EQ(a, b)
+#else
+  #define EXPECT_MJTNUM_EQ(a, b) EXPECT_DOUBLE_EQ(a, b)
+#endif
+
 // Installs and uninstalls error callbacks on MuJoCo that fail the currently
 // running test if triggered. Prefer the use of MujocoTest, unless using a
 // test fixture is not possible.