diff --git a/media/libheadtracking/QuaternionUtil-test.cpp b/media/libheadtracking/QuaternionUtil-test.cpp
new file mode 100644
index 0000000..e79e54a
--- /dev/null
+++ b/media/libheadtracking/QuaternionUtil-test.cpp
@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include "QuaternionUtil.h"
+#include "TestUtil.h"
+
+using Eigen::Quaternionf;
+using Eigen::Vector3f;
+
+namespace android {
+namespace media {
+namespace {
+
+TEST(QuaternionUtil, RotationVectorToQuaternion) {
+    // 90 degrees around Z.
+    Vector3f rot = {0, 0, M_PI_2};
+    Quaternionf quat = rotationVectorToQuaternion(rot);
+    ASSERT_EQ(quat * Vector3f(1, 0, 0), Vector3f(0, 1, 0));
+    ASSERT_EQ(quat * Vector3f(0, 1, 0), Vector3f(-1, 0, 0));
+    ASSERT_EQ(quat * Vector3f(0, 0, 1), Vector3f(0, 0, 1));
+}
+
+TEST(QuaternionUtil, QuaternionToRotationVector) {
+    Quaternionf quat = Quaternionf::FromTwoVectors(Vector3f(1, 0, 0), Vector3f(0, 1, 0));
+    Vector3f rot = quaternionToRotationVector(quat);
+    ASSERT_EQ(rot, Vector3f(0, 0, M_PI_2));
+}
+
+TEST(QuaternionUtil, RoundTripFromQuaternion) {
+    Quaternionf quaternion = Quaternionf::UnitRandom();
+    EXPECT_EQ(quaternion, rotationVectorToQuaternion(quaternionToRotationVector(quaternion)));
+}
+
+TEST(QuaternionUtil, RoundTripFromVector) {
+    Vector3f vec{0.1, 0.2, 0.3};
+    EXPECT_EQ(vec, quaternionToRotationVector(rotationVectorToQuaternion(vec)));
+}
+
+}  // namespace
+}  // namespace media
+}  // namespace android