diff --git a/media/libheadtracking/QuaternionUtil-test.cpp b/media/libheadtracking/QuaternionUtil-test.cpp
index ebb4223..cfeca00 100644
--- a/media/libheadtracking/QuaternionUtil-test.cpp
+++ b/media/libheadtracking/QuaternionUtil-test.cpp
@@ -51,6 +51,92 @@
     EXPECT_EQ(vec, quaternionToRotationVector(rotationVectorToQuaternion(vec)));
 }
 
+// Float precision necessitates this precision (1e-4f fails)
+constexpr float NEAR = 1e-3f;
+
+TEST(QuaternionUtil, quaternionToAngles_basic) {
+    float pitch, roll, yaw;
+
+   // angles as reported.
+   // choose 11 angles between -M_PI / 2 to M_PI / 2
+    for (int step = -5; step <= 5; ++step) {
+        const float angle = M_PI * step * 0.1f;
+
+        quaternionToAngles(rotationVectorToQuaternion({angle, 0.f, 0.f}), &pitch, &roll, &yaw);
+        EXPECT_NEAR(angle, pitch, NEAR);
+        EXPECT_NEAR(0.f, roll, NEAR);
+        EXPECT_NEAR(0.f, yaw, NEAR);
+
+        quaternionToAngles(rotationVectorToQuaternion({0.f, angle, 0.f}), &pitch, &roll, &yaw);
+        EXPECT_NEAR(0.f, pitch, NEAR);
+        EXPECT_NEAR(angle, roll, NEAR);
+        EXPECT_NEAR(0.f, yaw, NEAR);
+
+        quaternionToAngles(rotationVectorToQuaternion({0.f, 0.f, angle}), &pitch, &roll, &yaw);
+        EXPECT_NEAR(0.f, pitch, NEAR);
+        EXPECT_NEAR(0.f, roll, NEAR);
+        EXPECT_NEAR(angle, yaw, NEAR);
+    }
+
+    // Generates a debug string
+    const std::string s = quaternionToAngles<true /* DEBUG */>(
+            rotationVectorToQuaternion({M_PI, 0.f, 0.f}), &pitch, &roll, &yaw);
+    ASSERT_FALSE(s.empty());
+}
+
+TEST(QuaternionUtil, quaternionToAngles_zaxis) {
+    float pitch, roll, yaw;
+
+    for (int rot_step = -10; rot_step <= 10; ++rot_step) {
+        const float rot_angle = M_PI * rot_step * 0.1f;
+        // pitch independent of world Z rotation
+
+        // We don't test the boundaries of pitch +-M_PI/2 as roll can become
+        // degenerate and atan(0, 0) may report 0, PI, or -PI.
+        for (int step = -4; step <= 4; ++step) {
+            const float angle = M_PI * step * 0.1f;
+            auto q = rotationVectorToQuaternion({angle, 0.f, 0.f});
+            auto world_z = rotationVectorToQuaternion({0.f, 0.f, rot_angle});
+
+            // Sequential active rotations (on world frame) compose as R_2 * R_1.
+            quaternionToAngles(world_z * q, &pitch, &roll, &yaw);
+
+            EXPECT_NEAR(angle, pitch, NEAR);
+            EXPECT_NEAR(0.f, roll, NEAR);
+       }
+
+        // roll independent of world Z rotation
+        for (int step = -5; step <= 5; ++step) {
+            const float angle = M_PI * step * 0.1f;
+            auto q = rotationVectorToQuaternion({0.f, angle, 0.f});
+            auto world_z = rotationVectorToQuaternion({0.f, 0.f, rot_angle});
+
+            // Sequential active rotations (on world frame) compose as R_2 * R_1.
+            quaternionToAngles(world_z * q, &pitch, &roll, &yaw);
+
+            EXPECT_NEAR(0.f, pitch, NEAR);
+            EXPECT_NEAR(angle, roll, NEAR);
+
+            // Convert extrinsic (world-based) active rotations to a sequence of
+            // intrinsic rotations (each rotation based off of previous rotation
+            // frame).
+            //
+            // R_1 * R_intrinsic = R_extrinsic * R_1
+            //    implies
+            // R_intrinsic = (R_1)^-1 R_extrinsic R_1
+            //
+            auto world_z_intrinsic = rotationVectorToQuaternion(
+                    q.inverse() * Vector3f(0.f, 0.f, rot_angle));
+
+            // Sequential intrinsic rotations compose as R_1 * R_2.
+            quaternionToAngles(q * world_z_intrinsic, &pitch, &roll, &yaw);
+
+            EXPECT_NEAR(0.f, pitch, NEAR);
+            EXPECT_NEAR(angle, roll, NEAR);
+        }
+    }
+}
+
 }  // namespace
 }  // namespace media
 }  // namespace android