diff --git a/media/libaudioprocessing/tests/Android.bp b/media/libaudioprocessing/tests/Android.bp
index 3856817..ad402db 100644
--- a/media/libaudioprocessing/tests/Android.bp
+++ b/media/libaudioprocessing/tests/Android.bp
@@ -76,6 +76,7 @@
 //
 cc_binary {
     name: "mixerops_objdump",
+    header_libs: ["libaudioutils_headers"],
     srcs: ["mixerops_objdump.cpp"],
 }
 
@@ -84,6 +85,16 @@
 //
 cc_benchmark {
     name: "mixerops_benchmark",
+    header_libs: ["libaudioutils_headers"],
     srcs: ["mixerops_benchmark.cpp"],
     static_libs: ["libgoogle-benchmark"],
 }
+
+//
+// mixerops unit test
+//
+cc_test {
+    name: "mixerops_tests",
+    defaults: ["libaudioprocessing_test_defaults"],
+    srcs: ["mixerops_tests.cpp"],
+}
diff --git a/media/libaudioprocessing/tests/mixerops_benchmark.cpp b/media/libaudioprocessing/tests/mixerops_benchmark.cpp
index 7a4c5c7..f866b1a 100644
--- a/media/libaudioprocessing/tests/mixerops_benchmark.cpp
+++ b/media/libaudioprocessing/tests/mixerops_benchmark.cpp
@@ -16,11 +16,9 @@
 
 #include <inttypes.h>
 #include <type_traits>
-#include "../../../../system/media/audio_utils/include/audio_utils/primitives.h"
 #define LOG_ALWAYS_FATAL(...)
 
 #include <../AudioMixerOps.h>
-
 #include <benchmark/benchmark.h>
 
 using namespace android;
diff --git a/media/libaudioprocessing/tests/mixerops_tests.cpp b/media/libaudioprocessing/tests/mixerops_tests.cpp
new file mode 100644
index 0000000..2500ba9
--- /dev/null
+++ b/media/libaudioprocessing/tests/mixerops_tests.cpp
@@ -0,0 +1,175 @@
+/*
+ * 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.
+ */
+
+//#define LOG_NDEBUG 0
+#define LOG_TAG "mixerop_tests"
+#include <log/log.h>
+
+#include <inttypes.h>
+#include <type_traits>
+
+#include <../AudioMixerOps.h>
+#include <gtest/gtest.h>
+
+using namespace android;
+
+// Note: gtest templated tests require typenames, not integers.
+template <int MIXTYPE, int NCHAN>
+class MixerOpsBasicTest {
+public:
+    static void testStereoVolume() {
+        using namespace android::audio_utils::channels;
+
+        constexpr size_t FRAME_COUNT = 1000;
+        constexpr size_t SAMPLE_COUNT = FRAME_COUNT * NCHAN;
+
+        const float in[SAMPLE_COUNT] = {[0 ... (SAMPLE_COUNT - 1)] = 1.f};
+
+        AUDIO_GEOMETRY_SIDE sides[NCHAN];
+        size_t i = 0;
+        unsigned channel = canonicalChannelMaskFromCount(NCHAN);
+        constexpr unsigned LFE_LFE2 =
+                AUDIO_CHANNEL_OUT_LOW_FREQUENCY | AUDIO_CHANNEL_OUT_LOW_FREQUENCY_2;
+        bool has_LFE_LFE2 = (channel & LFE_LFE2) == LFE_LFE2;
+        while (channel != 0) {
+            const int index = __builtin_ctz(channel);
+            if (has_LFE_LFE2 && (1 << index) == AUDIO_CHANNEL_OUT_LOW_FREQUENCY) {
+                sides[i++] = AUDIO_GEOMETRY_SIDE_LEFT; // special case
+            } else if (has_LFE_LFE2 && (1 << index) == AUDIO_CHANNEL_OUT_LOW_FREQUENCY_2) {
+                sides[i++] = AUDIO_GEOMETRY_SIDE_RIGHT; // special case
+            } else {
+                sides[i++] = sideFromChannelIdx(index);
+            }
+            channel &= ~(1 << index);
+        }
+
+        float vola[2] = {1.f, 0.f}; // left volume at max.
+        float out[SAMPLE_COUNT]{};
+        float aux[FRAME_COUNT]{};
+        float volaux = 0.5;
+        {
+            volumeMulti<MIXTYPE, NCHAN>(out, FRAME_COUNT, in, aux, vola, volaux);
+            const float *outp = out;
+            const float *auxp = aux;
+            const float left = vola[0];
+            const float center = (vola[0] + vola[1]) * 0.5;
+            const float right = vola[1];
+            for (size_t i = 0; i < FRAME_COUNT; ++i) {
+                for (size_t j = 0; j < NCHAN; ++j) {
+                    const float audio = *outp++;
+                    if (sides[j] == AUDIO_GEOMETRY_SIDE_LEFT) {
+                        EXPECT_EQ(left, audio);
+                    } else if (sides[j] == AUDIO_GEOMETRY_SIDE_CENTER) {
+                        EXPECT_EQ(center, audio);
+                    } else {
+                        EXPECT_EQ(right, audio);
+                    }
+                }
+                EXPECT_EQ(volaux, *auxp++);  // works if all channels contain 1.f
+            }
+        }
+        float volb[2] = {0.f, 0.5f}; // right volume at half max.
+        {
+            // this accumulates into out, aux.
+            // float out[SAMPLE_COUNT]{};
+            // float aux[FRAME_COUNT]{};
+            volumeMulti<MIXTYPE, NCHAN>(out, FRAME_COUNT, in, aux, volb, volaux);
+            const float *outp = out;
+            const float *auxp = aux;
+            const float left = vola[0] + volb[0];
+            const float center = (vola[0] + vola[1] + volb[0] + volb[1]) * 0.5;
+            const float right = vola[1] + volb[1];
+            for (size_t i = 0; i < FRAME_COUNT; ++i) {
+                for (size_t j = 0; j < NCHAN; ++j) {
+                    const float audio = *outp++;
+                    if (sides[j] == AUDIO_GEOMETRY_SIDE_LEFT) {
+                        EXPECT_EQ(left, audio);
+                    } else if (sides[j] == AUDIO_GEOMETRY_SIDE_CENTER) {
+                        EXPECT_EQ(center, audio);
+                    } else {
+                        EXPECT_EQ(right, audio);
+                    }
+                }
+                // aux is accumulated so 2x the amplitude
+                EXPECT_EQ(volaux * 2.f, *auxp++);  // works if all channels contain 1.f
+            }
+        }
+
+        { // test aux as derived from out.
+            // AUX channel is the weighted sum of all of the output channels prior to volume
+            // adjustment.  We must set L and R to the same volume to allow computation
+            // of AUX from the output values.
+            const float volmono = 0.25f;
+            const float vollr[2] = {volmono, volmono}; // all the same.
+            float out[SAMPLE_COUNT]{};
+            float aux[FRAME_COUNT]{};
+            volumeMulti<MIXTYPE, NCHAN>(out, FRAME_COUNT, in, aux, vollr, volaux);
+            const float *outp = out;
+            const float *auxp = aux;
+            for (size_t i = 0; i < FRAME_COUNT; ++i) {
+                float accum = 0.f;
+                for (size_t j = 0; j < NCHAN; ++j) {
+                    accum += *outp++;
+                }
+                EXPECT_EQ(accum / NCHAN * volaux / volmono, *auxp++);
+            }
+        }
+    }
+};
+
+TEST(mixerops, stereovolume_1) { // Note: mono not used for output sinks yet.
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 1>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_2) {
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 2>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_3) {
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 3>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_4) {
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 4>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_5) {
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 5>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_6) {
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 6>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_7) {
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 7>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_8) {
+    MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 8>::testStereoVolume();
+}
+TEST(mixerops, stereovolume_12) {
+    if constexpr (FCC_LIMIT >= 12) { // NOTE: FCC_LIMIT is an enum, so can't #if
+        MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 12>::testStereoVolume();
+    }
+}
+TEST(mixerops, stereovolume_24) {
+    if constexpr (FCC_LIMIT >= 24) {
+        MixerOpsBasicTest<MIXTYPE_MULTI_STEREOVOL, 24>::testStereoVolume();
+    }
+}
+TEST(mixerops, channel_equivalence) {
+    // we must match the constexpr function with the system determined channel mask from count.
+    for (size_t i = 0; i < FCC_LIMIT; ++i) {
+        const audio_channel_mask_t actual = canonicalChannelMaskFromCount(i);
+        const audio_channel_mask_t system = audio_channel_out_mask_from_count(i);
+        if (system == AUDIO_CHANNEL_INVALID) continue;
+        EXPECT_EQ(system, actual);
+    }
+}