diff --git a/services/surfaceflinger/tests/Android.mk b/services/surfaceflinger/tests/Android.mk
index 5053e7d..b655648 100644
--- a/services/surfaceflinger/tests/Android.mk
+++ b/services/surfaceflinger/tests/Android.mk
@@ -1 +1,40 @@
-include $(call all-subdir-makefiles)
+# Build the unit tests,
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := SurfaceFlinger_test
+
+LOCAL_MODULE_TAGS := tests
+
+LOCAL_SRC_FILES := \
+    Transaction_test.cpp \
+
+LOCAL_SHARED_LIBRARIES := \
+	libEGL \
+	libGLESv2 \
+	libandroid \
+	libbinder \
+	libcutils \
+	libgui \
+	libstlport \
+	libui \
+	libutils \
+
+LOCAL_C_INCLUDES := \
+    bionic \
+    bionic/libstdc++/include \
+    external/gtest/include \
+    external/stlport/stlport \
+
+# Build the binary to $(TARGET_OUT_DATA_NATIVE_TESTS)/$(LOCAL_MODULE)
+# to integrate with auto-test framework.
+include $(BUILD_NATIVE_TEST)
+
+# Include subdirectory makefiles
+# ============================================================
+
+# If we're building with ONE_SHOT_MAKEFILE (mm, mmm), then what the framework
+# team really wants is to build the stuff defined by this makefile.
+ifeq (,$(ONE_SHOT_MAKEFILE))
+include $(call first-makefiles-under,$(LOCAL_PATH))
+endif
diff --git a/services/surfaceflinger/tests/Transaction_test.cpp b/services/surfaceflinger/tests/Transaction_test.cpp
new file mode 100644
index 0000000..afafd8a
--- /dev/null
+++ b/services/surfaceflinger/tests/Transaction_test.cpp
@@ -0,0 +1,236 @@
+/*
+ * Copyright (C) 2011 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 <binder/IMemory.h>
+#include <surfaceflinger/ISurfaceComposer.h>
+#include <surfaceflinger/Surface.h>
+#include <surfaceflinger/SurfaceComposerClient.h>
+#include <utils/String8.h>
+
+namespace android {
+
+// Fill an RGBA_8888 formatted surface with a single color.
+static void fillSurfaceRGBA8(const sp<SurfaceControl>& sc,
+        uint8_t r, uint8_t g, uint8_t b) {
+    Surface::SurfaceInfo info;
+    sp<Surface> s = sc->getSurface();
+    ASSERT_TRUE(s != NULL);
+    ASSERT_EQ(NO_ERROR, s->lock(&info));
+    uint8_t* img = reinterpret_cast<uint8_t*>(info.bits);
+    for (uint32_t y = 0; y < info.h; y++) {
+        for (uint32_t x = 0; x < info.w; x++) {
+            uint8_t* pixel = img + (4 * (y*info.s + x));
+            pixel[0] = r;
+            pixel[1] = g;
+            pixel[2] = b;
+            pixel[3] = 255;
+        }
+    }
+    ASSERT_EQ(NO_ERROR, s->unlockAndPost());
+}
+
+// A ScreenCapture is a screenshot from SurfaceFlinger that can be used to check
+// individual pixel values for testing purposes.
+class ScreenCapture : public RefBase {
+public:
+    static void captureScreen(sp<ScreenCapture>* sc) {
+        sp<IMemoryHeap> heap;
+        uint32_t w=0, h=0;
+        PixelFormat fmt=0;
+        sp<ISurfaceComposer> sf(ComposerService::getComposerService());
+        ASSERT_EQ(NO_ERROR, sf->captureScreen(0, &heap, &w, &h, &fmt, 0, 0,
+                0, INT_MAX));
+        ASSERT_TRUE(heap != NULL);
+        ASSERT_EQ(PIXEL_FORMAT_RGBA_8888, fmt);
+        *sc = new ScreenCapture(w, h, heap);
+    }
+
+    void checkPixel(uint32_t x, uint32_t y, uint8_t r, uint8_t g, uint8_t b) {
+        const uint8_t* img = reinterpret_cast<const uint8_t*>(mHeap->base());
+        const uint8_t* pixel = img + (4 * (y*mWidth + x));
+        if (r != pixel[0] || g != pixel[1] || b != pixel[2]) {
+            String8 err(String8::format("pixel @ (%3d, %3d): "
+                    "expected [%3d, %3d, %3d], got [%3d, %3d, %3d]",
+                    x, y, r, g, b, pixel[0], pixel[1], pixel[2]));
+            EXPECT_EQ(String8(), err);
+        }
+    }
+
+private:
+    ScreenCapture(uint32_t w, uint32_t h, const sp<IMemoryHeap>& heap) :
+        mWidth(w),
+        mHeight(h),
+        mHeap(heap)
+    {}
+
+    const uint32_t mWidth;
+    const uint32_t mHeight;
+    sp<IMemoryHeap> mHeap;
+};
+
+class LayerUpdateTest : public ::testing::Test {
+protected:
+    virtual void SetUp() {
+        mComposerClient = new SurfaceComposerClient;
+        ASSERT_EQ(NO_ERROR, mComposerClient->initCheck());
+
+        ssize_t displayWidth = mComposerClient->getDisplayWidth(0);
+        ssize_t displayHeight = mComposerClient->getDisplayHeight(0);
+
+        // Background surface
+        mBGSurfaceControl = mComposerClient->createSurface(
+                String8("BG Test Surface"), 0, displayWidth, displayHeight,
+                PIXEL_FORMAT_RGBA_8888, 0);
+        ASSERT_TRUE(mBGSurfaceControl != NULL);
+        ASSERT_TRUE(mBGSurfaceControl->isValid());
+        fillSurfaceRGBA8(mBGSurfaceControl, 63, 63, 195);
+
+        // Foreground surface
+        mFGSurfaceControl = mComposerClient->createSurface(
+                String8("FG Test Surface"), 0, 64, 64, PIXEL_FORMAT_RGBA_8888, 0);
+        ASSERT_TRUE(mFGSurfaceControl != NULL);
+        ASSERT_TRUE(mFGSurfaceControl->isValid());
+
+        fillSurfaceRGBA8(mFGSurfaceControl, 195, 63, 63);
+
+        // Synchronization surface
+        mSyncSurfaceControl = mComposerClient->createSurface(
+                String8("Sync Test Surface"), 0, 1, 1, PIXEL_FORMAT_RGBA_8888, 0);
+        ASSERT_TRUE(mSyncSurfaceControl != NULL);
+        ASSERT_TRUE(mSyncSurfaceControl->isValid());
+
+        fillSurfaceRGBA8(mSyncSurfaceControl, 31, 31, 31);
+
+        SurfaceComposerClient::openGlobalTransaction();
+
+        ASSERT_EQ(NO_ERROR, mBGSurfaceControl->setLayer(INT_MAX-2));
+        ASSERT_EQ(NO_ERROR, mBGSurfaceControl->show());
+
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setLayer(INT_MAX-1));
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setPosition(64, 64));
+        ASSERT_EQ(NO_ERROR, mFGSurfaceControl->show());
+
+        ASSERT_EQ(NO_ERROR, mSyncSurfaceControl->setLayer(INT_MAX-1));
+        ASSERT_EQ(NO_ERROR, mSyncSurfaceControl->setPosition(displayWidth-2,
+                displayHeight-2));
+        ASSERT_EQ(NO_ERROR, mSyncSurfaceControl->show());
+
+        SurfaceComposerClient::closeGlobalTransaction(true);
+    }
+
+    virtual void TearDown() {
+        mComposerClient->dispose();
+        mBGSurfaceControl = 0;
+        mFGSurfaceControl = 0;
+        mSyncSurfaceControl = 0;
+        mComposerClient = 0;
+    }
+
+    void waitForPostedBuffers() {
+        // Since the sync surface is in synchronous mode (i.e. double buffered)
+        // posting three buffers to it should ensure that at least two
+        // SurfaceFlinger::handlePageFlip calls have been made, which should
+        // guaranteed that a buffer posted to another Surface has been retired.
+        fillSurfaceRGBA8(mSyncSurfaceControl, 31, 31, 31);
+        fillSurfaceRGBA8(mSyncSurfaceControl, 31, 31, 31);
+        fillSurfaceRGBA8(mSyncSurfaceControl, 31, 31, 31);
+    }
+
+    sp<SurfaceComposerClient> mComposerClient;
+    sp<SurfaceControl> mBGSurfaceControl;
+    sp<SurfaceControl> mFGSurfaceControl;
+
+    // This surface is used to ensure that the buffers posted to
+    // mFGSurfaceControl have been picked up by SurfaceFlinger.
+    sp<SurfaceControl> mSyncSurfaceControl;
+};
+
+TEST_F(LayerUpdateTest, LayerMoveWorks) {
+    sp<ScreenCapture> sc;
+    {
+        SCOPED_TRACE("before move");
+        ScreenCapture::captureScreen(&sc);
+        sc->checkPixel(  0,  12,  63,  63, 195);
+        sc->checkPixel( 75,  75, 195,  63,  63);
+        sc->checkPixel(145, 145,  63,  63, 195);
+    }
+
+    SurfaceComposerClient::openGlobalTransaction();
+    ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setPosition(128, 128));
+    SurfaceComposerClient::closeGlobalTransaction(true);
+    {
+        // This should reflect the new position, but not the new color.
+        SCOPED_TRACE("after move, before redraw");
+        ScreenCapture::captureScreen(&sc);
+        sc->checkPixel( 24,  24,  63,  63, 195);
+        sc->checkPixel( 75,  75,  63,  63, 195);
+        sc->checkPixel(145, 145, 195,  63,  63);
+    }
+
+    fillSurfaceRGBA8(mFGSurfaceControl, 63, 195, 63);
+    waitForPostedBuffers();
+    {
+        // This should reflect the new position and the new color.
+        SCOPED_TRACE("after redraw");
+        ScreenCapture::captureScreen(&sc);
+        sc->checkPixel( 24,  24,  63,  63, 195);
+        sc->checkPixel( 75,  75,  63,  63, 195);
+        sc->checkPixel(145, 145,  63, 195,  63);
+    }
+}
+
+TEST_F(LayerUpdateTest, LayerResizeWorks) {
+    sp<ScreenCapture> sc;
+    {
+        SCOPED_TRACE("before resize");
+        ScreenCapture::captureScreen(&sc);
+        sc->checkPixel(  0,  12,  63,  63, 195);
+        sc->checkPixel( 75,  75, 195,  63,  63);
+        sc->checkPixel(145, 145,  63,  63, 195);
+    }
+
+    LOGD("resizing");
+    SurfaceComposerClient::openGlobalTransaction();
+    ASSERT_EQ(NO_ERROR, mFGSurfaceControl->setSize(128, 128));
+    SurfaceComposerClient::closeGlobalTransaction(true);
+    LOGD("resized");
+    {
+        // This should not reflect the new size or color because SurfaceFlinger
+        // has not yet received a buffer of the correct size.
+        SCOPED_TRACE("after resize, before redraw");
+        ScreenCapture::captureScreen(&sc);
+        sc->checkPixel(  0,  12,  63,  63, 195);
+        sc->checkPixel( 75,  75, 195,  63,  63);
+        sc->checkPixel(145, 145,  63,  63, 195);
+    }
+
+    LOGD("drawing");
+    fillSurfaceRGBA8(mFGSurfaceControl, 63, 195, 63);
+    waitForPostedBuffers();
+    LOGD("drawn");
+    {
+        // This should reflect the new size and the new color.
+        SCOPED_TRACE("after redraw");
+        ScreenCapture::captureScreen(&sc);
+        sc->checkPixel( 24,  24,  63,  63, 195);
+        sc->checkPixel( 75,  75,  63, 195,  63);
+        sc->checkPixel(145, 145,  63, 195,  63);
+    }
+}
+
+}