diff --git a/media/libheadtracking/Twist-test.cpp b/media/libheadtracking/Twist-test.cpp
new file mode 100644
index 0000000..7984e1e
--- /dev/null
+++ b/media/libheadtracking/Twist-test.cpp
@@ -0,0 +1,67 @@
+/*
+ * 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 "media/Twist.h"
+
+#include <gtest/gtest.h>
+
+#include "QuaternionUtil.h"
+#include "TestUtil.h"
+
+using Eigen::Quaternionf;
+using Eigen::Vector3f;
+
+namespace android {
+namespace media {
+namespace {
+
+TEST(Twist, DefaultCtor) {
+    Twist3f twist;
+    EXPECT_EQ(twist.translationalVelocity(), Vector3f::Zero());
+    EXPECT_EQ(twist.rotationalVelocity(), Vector3f::Zero());
+    EXPECT_FLOAT_EQ(twist.scalarRotationalVelocity(), 0);
+    EXPECT_FLOAT_EQ(twist.scalarTranslationalVelocity(), 0);
+}
+
+TEST(Twist, FullCtor) {
+    Vector3f rot{1, 2, 3};
+    Vector3f trans{4, 5, 6};
+    Twist3f twist(trans, rot);
+    EXPECT_EQ(twist.translationalVelocity(), trans);
+    EXPECT_EQ(twist.rotationalVelocity(), rot);
+    EXPECT_FLOAT_EQ(twist.scalarRotationalVelocity(), std::sqrt(14.f));
+    EXPECT_FLOAT_EQ(twist.scalarTranslationalVelocity(), std::sqrt(77.f));
+}
+
+TEST(Twist, Integrate) {
+    Vector3f trans{1, 2, 3};
+    // 45 deg/sec around Z.
+    Vector3f rot{0, 0, M_PI_4};
+    Twist3f twist(trans, rot);
+    Pose3f pose = integrate(twist, 2.f);
+
+    EXPECT_EQ(pose, Pose3f(Vector3f{2, 4, 6}, rotateZ(M_PI_2)));
+}
+
+TEST(Twist, Differentiate) {
+    Pose3f pose(Vector3f{2, 4, 6}, rotateZ(M_PI_2));
+    Twist3f twist = differentiate(pose, 2.f);
+    EXPECT_EQ(twist, Twist3f(Vector3f(1, 2, 3), Vector3f(0, 0, M_PI_4)));
+}
+
+}  // namespace
+}  // namespace media
+}  // namespace android