diff --git a/services/surfaceflinger/SurfaceFlinger.cpp b/services/surfaceflinger/SurfaceFlinger.cpp
index 1ef381c..d8b920e 100644
--- a/services/surfaceflinger/SurfaceFlinger.cpp
+++ b/services/surfaceflinger/SurfaceFlinger.cpp
@@ -863,30 +863,32 @@
         ALOGE("Run StartPropertySetThread failed!");
     }
 
-    if (mTransactionTracing) {
-        TransactionTraceWriter::getInstance().setWriterFunction([&](const std::string& prefix,
-                                                                    bool overwrite) {
-            auto writeFn = [&]() {
-                const std::string filename =
-                        TransactionTracing::DIR_NAME + prefix + TransactionTracing::FILE_NAME;
-                if (!overwrite && access(filename.c_str(), F_OK) == 0) {
-                    ALOGD("TransactionTraceWriter: file=%s already exists", filename.c_str());
-                    return;
-                }
-                mTransactionTracing->flush();
-                mTransactionTracing->writeToFile(filename);
-            };
-            if (std::this_thread::get_id() == mMainThreadId) {
-                writeFn();
-            } else {
-                mScheduler->schedule(writeFn).get();
-            }
-        });
-    }
-
+    initTransactionTraceWriter();
     ALOGV("Done initializing");
 }
 
+void SurfaceFlinger::initTransactionTraceWriter() {
+    if (!mTransactionTracing) {
+        return;
+    }
+    TransactionTraceWriter::getInstance().setWriterFunction(
+            [&](const std::string& filename, bool overwrite) {
+                auto writeFn = [&]() {
+                    if (!overwrite && access(filename.c_str(), F_OK) == 0) {
+                        ALOGD("TransactionTraceWriter: file=%s already exists", filename.c_str());
+                        return;
+                    }
+                    mTransactionTracing->flush();
+                    mTransactionTracing->writeToFile(filename);
+                };
+                if (std::this_thread::get_id() == mMainThreadId) {
+                    writeFn();
+                } else {
+                    mScheduler->schedule(writeFn).get();
+                }
+            });
+}
+
 void SurfaceFlinger::readPersistentProperties() {
     Mutex::Autolock _l(mStateLock);
 
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 4d17fa7..175209f 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -1134,7 +1134,7 @@
     ui::Rotation getPhysicalDisplayOrientation(DisplayId, bool isPrimary) const
             REQUIRES(mStateLock);
     void traverseLegacyLayers(const LayerVector::Visitor& visitor) const;
-
+    void initTransactionTraceWriter();
     sp<StartPropertySetThread> mStartPropertySetThread;
     surfaceflinger::Factory& mFactory;
     pid_t mPid;
diff --git a/services/surfaceflinger/Tracing/TransactionTracing.h b/services/surfaceflinger/Tracing/TransactionTracing.h
index 31bca5f..422b5f3 100644
--- a/services/surfaceflinger/Tracing/TransactionTracing.h
+++ b/services/surfaceflinger/Tracing/TransactionTracing.h
@@ -73,12 +73,16 @@
     static constexpr auto TRACING_VERSION = 1;
 
 private:
+    friend class TransactionTraceWriter;
     friend class TransactionTracingTest;
     friend class SurfaceFlinger;
 
     static constexpr auto DIR_NAME = "/data/misc/wmtrace/";
     static constexpr auto FILE_NAME = "transactions_trace.winscope";
     static constexpr auto FILE_PATH = "/data/misc/wmtrace/transactions_trace.winscope";
+    static std::string getFilePath(const std::string& prefix) {
+        return DIR_NAME + prefix + FILE_NAME;
+    }
 
     mutable std::mutex mTraceLock;
     TransactionRingBuffer<proto::TransactionTraceFile, proto::TransactionTraceEntry> mBuffer
@@ -138,10 +142,16 @@
 
 public:
     void setWriterFunction(
-            std::function<void(const std::string& prefix, bool overwrite)> function) {
+            std::function<void(const std::string& filename, bool overwrite)> function) {
         mWriterFunction = std::move(function);
     }
-    void invoke(const std::string& prefix, bool overwrite) { mWriterFunction(prefix, overwrite); }
+    void invoke(const std::string& prefix, bool overwrite) {
+        mWriterFunction(TransactionTracing::getFilePath(prefix), overwrite);
+    }
+    /* pass in a complete file path for testing */
+    void invokeForTest(const std::string& filename, bool overwrite) {
+        mWriterFunction(filename, overwrite);
+    }
 };
 
 } // namespace android
diff --git a/services/surfaceflinger/tests/unittests/Android.bp b/services/surfaceflinger/tests/unittests/Android.bp
index 3dd33b9..7d8796f 100644
--- a/services/surfaceflinger/tests/unittests/Android.bp
+++ b/services/surfaceflinger/tests/unittests/Android.bp
@@ -66,6 +66,7 @@
         // option to false temporarily.
         address: true,
     },
+    static_libs: ["libc++fs"],
     srcs: [
         ":libsurfaceflinger_mock_sources",
         ":libsurfaceflinger_sources",
@@ -128,6 +129,7 @@
         "TransactionFrameTracerTest.cpp",
         "TransactionProtoParserTest.cpp",
         "TransactionSurfaceFrameTest.cpp",
+        "TransactionTraceWriterTest.cpp",
         "TransactionTracingTest.cpp",
         "TunnelModeEnabledReporterTest.cpp",
         "StrongTypingTest.cpp",
diff --git a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
index 02fa415..8458aa3 100644
--- a/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
+++ b/services/surfaceflinger/tests/unittests/TestableSurfaceFlinger.h
@@ -651,6 +651,11 @@
 
     auto fromHandle(const sp<IBinder>& handle) { return LayerHandle::getLayer(handle); }
 
+    auto initTransactionTraceWriter() {
+        mFlinger->mTransactionTracing.emplace();
+        return mFlinger->initTransactionTraceWriter();
+    }
+
     ~TestableSurfaceFlinger() {
         // All these pointer and container clears help ensure that GMock does
         // not report a leaked object, since the SurfaceFlinger instance may
@@ -664,6 +669,7 @@
         mFlinger->mCompositionEngine->setHwComposer(std::unique_ptr<HWComposer>());
         mFlinger->mRenderEngine = std::unique_ptr<renderengine::RenderEngine>();
         mFlinger->mCompositionEngine->setRenderEngine(mFlinger->mRenderEngine.get());
+        mFlinger->mTransactionTracing.reset();
     }
 
     /* ------------------------------------------------------------------------
diff --git a/services/surfaceflinger/tests/unittests/TransactionTraceWriterTest.cpp b/services/surfaceflinger/tests/unittests/TransactionTraceWriterTest.cpp
new file mode 100644
index 0000000..379135e
--- /dev/null
+++ b/services/surfaceflinger/tests/unittests/TransactionTraceWriterTest.cpp
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2023 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.
+ */
+
+#undef LOG_TAG
+#define LOG_TAG "TransactionTraceWriterTest"
+
+#include <gmock/gmock.h>
+#include <gtest/gtest.h>
+#include <log/log.h>
+#include <filesystem>
+
+#include "TestableSurfaceFlinger.h"
+
+namespace android {
+
+class TransactionTraceWriterTest : public testing::Test {
+protected:
+    std::string mFilename = "/data/local/tmp/testfile_transaction_trace.winscope";
+
+    void SetUp() { mFlinger.initTransactionTraceWriter(); }
+    void TearDown() { std::filesystem::remove(mFilename); }
+
+    void verifyTraceFile() {
+        std::fstream file(mFilename, std::ios::in);
+        ASSERT_TRUE(file.is_open());
+        std::string line;
+        char magicNumber[8];
+        file.read(magicNumber, 8);
+        EXPECT_EQ("\tTNXTRAC", std::string(magicNumber, magicNumber + 8));
+    }
+
+    TestableSurfaceFlinger mFlinger;
+};
+
+TEST_F(TransactionTraceWriterTest, canWriteToFile) {
+    TransactionTraceWriter::getInstance().invokeForTest(mFilename, /* overwrite */ true);
+    EXPECT_EQ(access(mFilename.c_str(), F_OK), 0);
+    verifyTraceFile();
+}
+
+TEST_F(TransactionTraceWriterTest, canOverwriteFile) {
+    std::string testLine = "test";
+    {
+        std::ofstream file(mFilename, std::ios::out);
+        file << testLine;
+    }
+    TransactionTraceWriter::getInstance().invokeForTest(mFilename, /* overwrite */ true);
+    verifyTraceFile();
+}
+
+TEST_F(TransactionTraceWriterTest, doNotOverwriteFile) {
+    std::string testLine = "test";
+    {
+        std::ofstream file(mFilename, std::ios::out);
+        file << testLine;
+    }
+    TransactionTraceWriter::getInstance().invokeForTest(mFilename, /* overwrite */ false);
+    {
+        std::fstream file(mFilename, std::ios::in);
+        ASSERT_TRUE(file.is_open());
+        std::string line;
+        std::getline(file, line);
+        EXPECT_EQ(line, testLine);
+    }
+}
+} // namespace android
\ No newline at end of file