diff --git a/.github/workflows/c-cpp.yml b/.github/workflows/c-cpp.yml
index 8fcce90..7e5e1b7 100644
--- a/.github/workflows/c-cpp.yml
+++ b/.github/workflows/c-cpp.yml
@@ -62,3 +62,14 @@ jobs:
           cmake --build cbuild
       working-directory: test
 
+    - name: Build stubbed tests
+      working-directory: stubbed_tests
+      run: |
+          mkdir build && cd build
+          CC=clang CXX=clang++ cmake -DCMAKE_BUILD_TYPE=RelWithDebug ..
+          cmake --build . -j $(nproc)
+
+    - name: Run stubbed tests
+      working-directory: stubbed_tests/build
+      run: ./stubbed_tests
+
diff --git a/lib/platform/linux/platform.c b/lib/platform/linux/platform.c
index c12cd23..a01289d 100644
--- a/lib/platform/linux/platform.c
+++ b/lib/platform/linux/platform.c
@@ -189,8 +189,6 @@ static void * poll_for_indication(void * unused)
     // Initially wait for 500ms before any polling
     uint32_t wait_before_next_polling_ms = 500;
 
-    m_polling_thread_state_request = POLLING_THREAD_RUN;
-
     while (m_polling_thread_state_request != POLLING_THREAD_STOP)
     {
         usleep(wait_before_next_polling_ms * 1000);
@@ -378,6 +376,7 @@ bool Platform_init(Platform_get_indication_f get_indication_f,
     }
 
     // Start a thread to poll for indication
+    m_polling_thread_state_request = POLLING_THREAD_RUN;
     if (pthread_create(&thread_polling, NULL, poll_for_indication, NULL) != 0)
     {
         LOGE("Cannot create polling thread\n");
diff --git a/stubbed_tests/CMakeLists.txt b/stubbed_tests/CMakeLists.txt
new file mode 100644
index 0000000..f39d0d3
--- /dev/null
+++ b/stubbed_tests/CMakeLists.txt
@@ -0,0 +1,79 @@
+cmake_minimum_required(VERSION 3.18)
+
+project(c-mesh-api-stubbed-tests LANGUAGES C CXX)
+
+set(CMAKE_CXX_STANDARD 20)
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE RelWithDebInfo)
+endif()
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+set(TEST_EXTRA_CFLAGS "" CACHE STRING "Extra compiler flags for WPC library and test code. For example '--coverage'.")
+set(TEST_EXTRA_LDFLAGS "" CACHE STRING "Extra linker flags for the test executable. For example '--coverage'.")
+separate_arguments(TEST_EXTRA_CFLAGS)
+separate_arguments(TEST_EXTRA_LDFLAGS)
+
+set(WPC_LIB_DIR "${CMAKE_CURRENT_LIST_DIR}/../lib/")
+
+include(FetchContent)
+FetchContent_Declare(
+    wpc-lib
+    SOURCE_DIR ${WPC_LIB_DIR}
+)
+FetchContent_Declare(
+  fuzztest
+  GIT_REPOSITORY https://github.com/google/fuzztest/
+  GIT_TAG 2025-08-05
+)
+FetchContent_MakeAvailable(wpc-lib fuzztest)
+
+enable_testing()
+
+fuzztest_setup_fuzzing_flags()
+add_executable(stubbed_tests
+    tests/basic_tests.cpp
+    tests/ul_fuzz_tests.cpp
+    tests/utils/queued_ul_data_handler.cpp
+)
+target_include_directories(stubbed_tests PRIVATE tests)
+
+add_subdirectory(serialstub)
+
+target_include_directories(serialstub PRIVATE ${WPC_LIB_DIR}/platform)
+
+##########
+# Somewhat hacky way to suppress warnings for fuzztest library. This allows us
+# to use stricter compile flags for warnings in our testing code that includes
+# files from the fuzztest.
+get_target_property(LIB_INCLUDE_DIRS fuzztest_fuzztest INTERFACE_INCLUDE_DIRECTORIES)
+if(LIB_INCLUDE_DIRS)
+    set_target_properties(fuzztest_fuzztest PROPERTIES
+        INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "${LIB_INCLUDE_DIRS}"
+    )
+endif()
+get_target_property(LIB_INCLUDE_DIRS fuzztest_fuzztest_gtest_main INTERFACE_INCLUDE_DIRECTORIES)
+if(LIB_INCLUDE_DIRS)
+    set_target_properties(fuzztest_fuzztest_gtest_main PROPERTIES
+        INTERFACE_SYSTEM_INCLUDE_DIRECTORIES "${LIB_INCLUDE_DIRS}"
+    )
+endif()
+##########
+
+target_compile_options(wpc                   PRIVATE ${TEST_EXTRA_CFLAGS} -Werror -Wall -Wextra)
+target_compile_options(wpc_platform          PRIVATE ${TEST_EXTRA_CFLAGS} -Werror -Wall -Wextra)
+target_compile_options(stubbed_tests PRIVATE ${TEST_EXTRA_CFLAGS} -Wall -Werror -Wextra)
+target_link_options(stubbed_tests PRIVATE ${TEST_EXTRA_LDFLAGS})
+
+# "serialstub" should come before "wpc_platform" so that the serial implementation
+# from "wpc_platform" is not taken into use.
+target_link_libraries(stubbed_tests PRIVATE
+    GTest::gmock
+    wpc
+    serialstub
+    wpc_platform
+)
+
+include(GoogleTest)
+link_fuzztest(stubbed_tests)
+gtest_discover_tests(stubbed_tests)
+
diff --git a/stubbed_tests/README.md b/stubbed_tests/README.md
new file mode 100644
index 0000000..6719a51
--- /dev/null
+++ b/stubbed_tests/README.md
@@ -0,0 +1,48 @@
+# Introduction
+
+These tests use a stub implementation for the serial interface and can be run
+without a real serial device. See README.md under serialstub for more detils.
+
+There are two types of tests included; regular unit tests and fuzz tests. The
+tests use [FuzzTest](https://github.com/google/fuzztest) and
+[GTest](https://github.com/google/googletest).
+
+# Requirements
+[Clang](https://clang.llvm.org/), since FuzzTest requires it.
+
+# Building
+FuzzTest tests can be run as unit tests or in fuzzing mode. For more
+information refer to FuzzTest documentation
+[here](https://github.com/google/fuzztest/blob/main/doc/quickstart-cmake.md).
+
+Example command to build for unit testing:
+
+```shell
+mkdir build && cd build
+CC=clang CXX=clang++ cmake -DCMAKE_BUILD_TYPE=RelWithDebug ..
+cmake --build . -j $(nproc)
+```
+
+# Running the tests
+
+To run unit tests together with fuzz tests in unit testing mode:
+```shell
+./stubbed_tests
+```
+
+Refer to FuzzTest documentation on how to run fuzz tests in fuzzing mode.
+
+## Naming conventions
+Test suites that support fuzzing should start with "Fuzz". This way you can
+filter tests when running, for example to run only fuzz tests:
+
+```shell
+./stubbed_tests --gtest_filter="Fuzz*"
+```
+
+And to run non-fuzz tests:
+
+```shell
+./stubbed_tests --gtest_filter="-Fuzz*"
+```
+
diff --git a/stubbed_tests/serialstub/CMakeLists.txt b/stubbed_tests/serialstub/CMakeLists.txt
new file mode 100644
index 0000000..c687438
--- /dev/null
+++ b/stubbed_tests/serialstub/CMakeLists.txt
@@ -0,0 +1,15 @@
+add_library(serialstub STATIC
+    ${CMAKE_CURRENT_LIST_DIR}/serialstub/serial.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/serialstub/serial_stub.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/serialstub/wpc_frame.cpp
+    ${CMAKE_CURRENT_LIST_DIR}/serialstub/misc/crc.cpp
+)
+
+target_include_directories(serialstub PUBLIC
+    ${PROJECT_SOURCE_DIR}/platform
+    ${CMAKE_CURRENT_LIST_DIR}
+)
+
+set_target_properties(serialstub PROPERTIES LINKER_LANGUAGE CXX)
+target_compile_options(serialstub PRIVATE -Wall -Werror -Wextra)
+
diff --git a/stubbed_tests/serialstub/README.md b/stubbed_tests/serialstub/README.md
new file mode 100644
index 0000000..a09a490
--- /dev/null
+++ b/stubbed_tests/serialstub/README.md
@@ -0,0 +1,17 @@
+# Introduction
+
+This is a stub serial implementation for the c-mesh-api platform interface
+(lib/platform/serial.h). Intended use is to build on top of the linux platform
+implementation. Since only serial.h is implemented, the resulting object from
+this stub should be linked before the default platform objects so that the
+default serial implementation is not taken into use, while rest of the platform
+implementation is.
+
+The stub has a wrapper for Dual MCU frames. A handler is assigned for each
+frame which is normally sent to the serial device. The handler should return
+responses for every call (these are called "confirm" or "indication" in the
+DualMCU API.)
+
+For more information, see the Wirepas DualMCU API documentation (for example
+[here](https://github.com/wirepas/wm-sdk-5g/blob/rel_1.2.0_5G/libraries/dualmcu/api/DualMcuAPI.md))
+
diff --git a/stubbed_tests/serialstub/serialstub/frame_handler.h b/stubbed_tests/serialstub/serialstub/frame_handler.h
new file mode 100644
index 0000000..982dcec
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/frame_handler.h
@@ -0,0 +1,37 @@
+#pragma once
+
+#include <memory>
+#include <vector>
+#include <serialstub/wpc_frame.h>
+
+class FrameHandler
+{
+public:
+    using ptr = std::shared_ptr<FrameHandler>;
+
+    virtual ~FrameHandler() = default;
+
+    /**
+    * \brief Handle a Dual-MCU API frame
+    *
+    * Handles a request frame and returns response frames. As an example,
+    * multiple responses to a single request are possible when responding to
+    * poll requests.
+    *
+    * In this context, a "request" is a frame sent by the application and a
+    * "response" is a frame sent by the stub back to the application.
+    *
+    * In Dual-MCU API specification, "request" messages are the following:
+    * - request
+    * - response
+    * And the "response" messages are the following:
+    * - confirm
+    * - indication
+    *
+    * \param  frame
+    *         Request frame to be handled
+    * \return Response frames
+    */
+    virtual std::vector<WpcFrame> Handle(const WpcFrame& frame) = 0;
+};
+
diff --git a/stubbed_tests/serialstub/serialstub/misc/crc.cpp b/stubbed_tests/serialstub/serialstub/misc/crc.cpp
new file mode 100644
index 0000000..a0bdbee
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/misc/crc.cpp
@@ -0,0 +1,13 @@
+#include "crc.h"
+
+uint16_t Crc::FromBuffer(const uint8_t* const buffer, const size_t length)
+{
+    uint16_t crc = 0xffff;
+    for (size_t i = 0; i < length; i++)
+    {
+        const uint8_t index = buffer[i] ^ (crc >> 8);
+        crc = crc_ccitt_lut[index] ^ (crc << 8);
+    }
+    return crc;
+}
+
diff --git a/stubbed_tests/serialstub/serialstub/misc/crc.h b/stubbed_tests/serialstub/serialstub/misc/crc.h
new file mode 100644
index 0000000..55fe347
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/misc/crc.h
@@ -0,0 +1,48 @@
+#pragma once
+
+#include <cstddef>
+#include <cstdint>
+
+namespace Crc
+{
+
+static const uint16_t crc_ccitt_lut[] =
+{
+    0x0000, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
+    0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
+    0x1231, 0x0210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
+    0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
+    0x2462, 0x3443, 0x0420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
+    0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
+    0x3653, 0x2672, 0x1611, 0x0630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
+    0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
+    0x48c4, 0x58e5, 0x6886, 0x78a7, 0x0840, 0x1861, 0x2802, 0x3823,
+    0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
+    0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0x0a50, 0x3a33, 0x2a12,
+    0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
+    0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0x0c60, 0x1c41,
+    0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
+    0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0x0e70,
+    0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
+    0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
+    0x1080, 0x00a1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
+    0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
+    0x02b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
+    0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
+    0x34e2, 0x24c3, 0x14a0, 0x0481, 0x7466, 0x6447, 0x5424, 0x4405,
+    0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
+    0x26d3, 0x36f2, 0x0691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
+    0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
+    0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x08e1, 0x3882, 0x28a3,
+    0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
+    0x4a75, 0x5a54, 0x6a37, 0x7a16, 0x0af1, 0x1ad0, 0x2ab3, 0x3a92,
+    0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
+    0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0x0cc1,
+    0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
+    0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0x0ed1, 0x1ef0
+};
+
+uint16_t FromBuffer(const uint8_t* const buffer, const size_t length);
+
+} // namespace Crc
+
diff --git a/stubbed_tests/serialstub/serialstub/serial.cpp b/stubbed_tests/serialstub/serialstub/serial.cpp
new file mode 100644
index 0000000..b986c2f
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/serial.cpp
@@ -0,0 +1,36 @@
+#include <serialstub/serial_stub.h>
+
+extern "C" {
+#include <serial.h>
+
+    int Serial_open([[maybe_unused]] const char * port_name, [[maybe_unused]] unsigned long bitrate)
+    {
+        return 0;
+    }
+
+    int Serial_close()
+    {
+        return 0;
+    }
+
+    int Serial_read(unsigned char * c, [[maybe_unused]] unsigned int timeout_ms)
+    {
+        if (const auto& byte = serial_stub.PopOutByte(); byte.has_value())
+        {
+            *c = *byte;
+            return 1;
+        }
+
+        return 0;
+    }
+
+    int Serial_write(const unsigned char * buffer, unsigned int buffer_size)
+    {
+        // This is ok because in practice, c-mesh-api always sends a whole
+        // frame with a single Serial_write command.
+        serial_stub.ReadAndHandleFrame(buffer, buffer_size);
+        return buffer_size;
+    }
+
+}
+
diff --git a/stubbed_tests/serialstub/serialstub/serial_stub.cpp b/stubbed_tests/serialstub/serialstub/serial_stub.cpp
new file mode 100644
index 0000000..626384b
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/serial_stub.cpp
@@ -0,0 +1,159 @@
+#include "serial_stub.h"
+
+std::optional<WpcFrame> SerialStub::ReadFrame(const uint8_t* const buffer, const size_t buffer_size)
+{
+    // Use value initialization for WpcFrame so that the underlying payload
+    // array is initialized with zeroes. This makes it easier to compare two
+    // arrays for assertions in the tests.
+    WpcFrame decoded {};
+    size_t read_index;
+    size_t write_index;
+    bool in_escape;
+    for (read_index = 0, write_index = 0, in_escape = false; read_index < buffer_size; read_index++)
+    {
+        const uint8_t byte = buffer[read_index];
+        if (byte == Slip::END)
+        {
+            continue;
+        }
+
+        auto decoded_bytes = reinterpret_cast<uint8_t*>(&decoded);
+
+        if (write_index >= sizeof(decoded))
+        {
+            // error, too big frame
+            return std::nullopt;
+        }
+
+        if (in_escape)
+        {
+            if (byte == Slip::ESC_END)
+            {
+                decoded_bytes[write_index++] = Slip::END;
+            }
+            else if (byte == Slip::ESC_ESC)
+            {
+                decoded_bytes[write_index++] = Slip::ESC;
+            }
+            else
+            {
+                // error, invalid byte
+                return std::nullopt;
+            }
+            in_escape = false;
+        }
+        else
+        {
+            if (byte == Slip::ESC)
+            {
+                in_escape = true;
+            }
+            else
+            {
+                decoded_bytes[write_index++] = byte;
+            }
+        }
+    }
+
+    // CRC probably ends up inside the payload at this point; fix it
+    auto wrong_crc_location = reinterpret_cast<uint16_t*>(&decoded.payload[decoded.payload_length]);
+    decoded.crc = *wrong_crc_location;
+    *wrong_crc_location = 0;
+
+    return decoded;
+}
+
+void SerialStub::ReadAndHandleFrame(const uint8_t* const buffer, const size_t buffer_size)
+{
+    const auto frame = ReadFrame(buffer, buffer_size);
+    if (frame.has_value())
+    {
+        HandleFrame(*frame);
+    }
+}
+
+void SerialStub::HandleFrame(const WpcFrame& frame)
+{
+    FrameHandler::ptr handler = nullptr;
+
+    {
+        std::lock_guard<std::mutex> lock(message_handlers_mutex);
+        if (auto it = message_handlers.find(frame.primitive_id); it != message_handlers.cend())
+        {
+            handler = it->second;
+        }
+    }
+
+    if (handler)
+    {
+        const auto& responses = handler->Handle(frame);
+        for (const auto& response : responses)
+        {
+            AddToOutQueue(response);
+        }
+    }
+}
+
+void SerialStub::AddFrameHandler(const uint8_t primitive_id, FrameHandler::ptr handler)
+{
+    std::lock_guard<std::mutex> lock(message_handlers_mutex);
+    message_handlers[primitive_id] = handler;
+}
+
+void SerialStub::ClearFrameHandlers()
+{
+    std::lock_guard<std::mutex> lock(message_handlers_mutex);
+    message_handlers.clear();
+}
+
+void SerialStub::AddToOutQueue(const WpcFrame& frame)
+{
+    out_queue.push_back(Slip::END);
+
+    auto frame_bytes = reinterpret_cast<const uint8_t*>(&frame);
+
+    static_assert(std::numeric_limits<decltype(WpcFrame::payload_length)>::max() <= sizeof(WpcFrame::payload));
+    const size_t payload_end_offset = offsetof(WpcFrame, payload) + frame.payload_length;
+    for (size_t i = 0; i < payload_end_offset; i++)
+    {
+        EncodeAndAddToOutQueue(frame_bytes[i]);
+    }
+
+    for (size_t i = offsetof(WpcFrame, crc); i < offsetof(WpcFrame, crc) + sizeof(WpcFrame::crc); i++)
+    {
+        EncodeAndAddToOutQueue(frame_bytes[i]);
+    }
+
+    out_queue.push_back(Slip::END);
+}
+
+void SerialStub::EncodeAndAddToOutQueue(const uint8_t byte)
+{
+    if (byte == Slip::END)
+    {
+        out_queue.push_back(Slip::ESC);
+        out_queue.push_back(Slip::ESC_END);
+    }
+    else if (byte == Slip::ESC)
+    {
+        out_queue.push_back(Slip::ESC);
+        out_queue.push_back(Slip::ESC_ESC);
+    }
+    else
+    {
+        out_queue.push_back(byte);
+    }
+}
+
+std::optional<uint8_t> SerialStub::PopOutByte()
+{
+    if (!out_queue.empty())
+    {
+        const uint8_t byte = out_queue.front();
+        out_queue.pop_front();
+        return byte;
+    }
+
+    return std::nullopt;
+}
+
diff --git a/stubbed_tests/serialstub/serialstub/serial_stub.h b/stubbed_tests/serialstub/serialstub/serial_stub.h
new file mode 100644
index 0000000..efb066e
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/serial_stub.h
@@ -0,0 +1,45 @@
+#pragma once
+
+#include <deque>
+#include <mutex>
+#include <optional>
+#include <unordered_map>
+
+#include <serialstub/frame_handler.h>
+#include <serialstub/wpc_frame.h>
+
+/*
+* Thread safety notes:
+* - Serial_write and the following Serial_read are always called from the same thread
+* - Serial_write and Serial_read calls can be done from different threads (main thread and poll thread)
+* - AddFrameHandler is locked because polling thread might be using a frame handler in the background
+*/
+class SerialStub
+{
+public:
+    void ReadAndHandleFrame(const uint8_t* const buffer, const size_t buffer_size);
+
+    void AddFrameHandler(const uint8_t primitive_id, FrameHandler::ptr handler);
+    void ClearFrameHandlers();
+    std::optional<uint8_t> PopOutByte();
+private:
+    struct Slip
+    {
+        inline static const uint8_t END = 0xC0;
+        inline static const uint8_t ESC = 0xDB;
+        inline static const uint8_t ESC_ESC = 0xDD;
+        inline static const uint8_t ESC_END = 0xDC;
+    };
+
+    std::optional<WpcFrame> ReadFrame(const uint8_t* const buffer, const size_t buffer_size);
+    void HandleFrame(const WpcFrame& frame);
+    void AddToOutQueue(const WpcFrame& frame);
+    void EncodeAndAddToOutQueue(const uint8_t byte);
+
+    std::mutex message_handlers_mutex;
+    std::unordered_map<uint8_t, FrameHandler::ptr> message_handlers;
+    std::deque<uint8_t> out_queue;
+};
+
+inline SerialStub serial_stub;
+
diff --git a/stubbed_tests/serialstub/serialstub/wpc_frame.cpp b/stubbed_tests/serialstub/serialstub/wpc_frame.cpp
new file mode 100644
index 0000000..10cb1e7
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/wpc_frame.cpp
@@ -0,0 +1,28 @@
+#include "wpc_frame.h"
+
+#include <algorithm>
+#include <serialstub/misc/crc.h>
+
+std::optional<WpcFrame> WpcFrame::Create(const uint8_t primitive_id,
+                                         const uint8_t frame_id,
+                                         const std::span<const uint8_t> payload)
+{
+    if (payload.size() > sizeof(WpcFrame::payload))
+    {
+        return std::nullopt;
+    }
+
+    WpcFrame frame {
+        .primitive_id = primitive_id,
+        .frame_id = frame_id,
+        .payload_length = static_cast<uint8_t>(payload.size()),
+        .payload = {0},
+        .crc = 0,
+    };
+
+    std::ranges::copy(payload, frame.payload.begin());
+    frame.crc = Crc::FromBuffer(reinterpret_cast<const uint8_t*>(&frame),
+                                offsetof(WpcFrame, payload) + frame.payload_length);
+
+    return frame;
+}
diff --git a/stubbed_tests/serialstub/serialstub/wpc_frame.h b/stubbed_tests/serialstub/serialstub/wpc_frame.h
new file mode 100644
index 0000000..e426b85
--- /dev/null
+++ b/stubbed_tests/serialstub/serialstub/wpc_frame.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include <cstdint>
+#include <array>
+#include <optional>
+#include <span>
+
+/**
+* \brief A Dual-MCU API frame
+*/
+struct [[gnu::packed]] WpcFrame
+{
+    uint8_t primitive_id;
+    uint8_t frame_id;
+    uint8_t payload_length;
+    std::array<uint8_t, UINT8_MAX> payload;
+    uint16_t crc;
+
+    /**
+    * \brief Construct a frame calculating payload length and CRC automatically
+    * \return std::nullopt if payload size is too large, std::optional holding
+    * the created WpcFrame otherwise.
+    */
+    static std::optional<WpcFrame> Create(const uint8_t primitive_id,
+                                          const uint8_t frame_id,
+                                          const std::span<const uint8_t> payload);
+};
+
diff --git a/stubbed_tests/tests/basic_tests.cpp b/stubbed_tests/tests/basic_tests.cpp
new file mode 100644
index 0000000..5aea8a7
--- /dev/null
+++ b/stubbed_tests/tests/basic_tests.cpp
@@ -0,0 +1,106 @@
+#include <gtest/gtest.h>
+#include <gmock/gmock.h>
+
+#include <serialstub/serial_stub.h>
+extern "C" {
+    #include <wpc.h>
+    #define LOG_MODULE_NAME (char*) "basic_tests"
+    #include <logger.h>
+}
+
+using namespace testing;
+
+class StubbedTest : public testing::Test
+{
+protected:
+    class MockFrameHandler : public FrameHandler
+    {
+    public:
+        MOCK_METHOD(std::vector<WpcFrame>, Handle, (const WpcFrame&), (override));
+    };
+
+    void SetUp() override
+    {
+        Platform_set_log_level(NO_LOG_LEVEL);
+        WPC_initialize("", 0);
+    }
+
+    void TearDown() override
+    {
+        // WPC_close takes some time
+        WPC_close();
+        // Expectations on mock objects are done when they are deleted here
+        serial_stub.ClearFrameHandlers();
+    }
+};
+
+TEST_F(StubbedTest, exampleVerifyingSentRequest)
+{
+    auto handler = std::make_shared<MockFrameHandler>();
+
+    const std::array<uint8_t, 16> TEST_KEY {
+        0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80,
+        0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
+    };
+
+    std::array<uint8_t, UINT8_MAX> EXPECTED_REQUEST_PAYLOAD {
+        13, // Attribute id
+        00, 0x10, // Attribute length
+        0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80,
+        0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
+    };
+
+    EXPECT_CALL(*handler, Handle(FieldsAre(0x0D, _, 19, EXPECTED_REQUEST_PAYLOAD, _)))
+        .Times(1);
+    serial_stub.AddFrameHandler(0x0D, handler);
+
+    WPC_set_cipher_key(TEST_KEY.data());
+}
+
+TEST_F(StubbedTest, exampleVerifyingSentRequestWithSavedArgument)
+{
+    auto handler = std::make_shared<MockFrameHandler>();
+
+    const std::array<uint8_t, 16> TEST_KEY {
+        0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80,
+        0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
+    };
+
+    std::array<uint8_t, UINT8_MAX> EXPECTED_REQUEST_PAYLOAD {
+        0x0D, 0x00, // Attribute id
+        0x10, // Attribute length
+        0x10, 0x20, 0x30, 0x40, 0x50, 0x60, 0x70, 0x80,
+        0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7, 0xA8,
+    };
+
+    WpcFrame sentFrame {};
+
+    EXPECT_CALL(*handler, Handle)
+        .Times(1)
+        .WillOnce(DoAll(SaveArg<0>(&sentFrame),
+                        Return(std::vector<WpcFrame>())));
+    serial_stub.AddFrameHandler(0x0D, handler);
+
+    WPC_set_cipher_key(TEST_KEY.data());
+
+    EXPECT_EQ(sentFrame.primitive_id, 0x0D);
+    EXPECT_EQ(sentFrame.payload_length, 19);
+    EXPECT_EQ(sentFrame.payload, EXPECTED_REQUEST_PAYLOAD);
+}
+
+TEST_F(StubbedTest, exampleUsingSameHandlerForMultiplePrimitives)
+{
+    auto handler = std::make_shared<MockFrameHandler>();
+
+    EXPECT_CALL(*handler, Handle)
+        .Times(2);
+
+    // 0x1B: MSAP-SCRATCHPAD_CLEAR.request
+    // 0x38: MSAP-SINK_COST_WRITE.request
+    serial_stub.AddFrameHandler(0x1B, handler);
+    serial_stub.AddFrameHandler(0x38, handler);
+
+    WPC_clear_local_scratchpad();
+    WPC_set_sink_cost(10);
+}
+
diff --git a/stubbed_tests/tests/ul_fuzz_tests.cpp b/stubbed_tests/tests/ul_fuzz_tests.cpp
new file mode 100644
index 0000000..b4342fb
--- /dev/null
+++ b/stubbed_tests/tests/ul_fuzz_tests.cpp
@@ -0,0 +1,116 @@
+#include <semaphore>
+#include <chrono>
+#include <fuzztest/fuzztest.h>
+#include <gtest/gtest.h>
+#include <gmock/gmock.h>
+#include <serialstub/serial_stub.h>
+#include <serialstub/misc/crc.h>
+#include <utils/data_structures.h>
+#include <utils/queued_ul_data_handler.h>
+extern "C" {
+#include <wpc.h>
+    #define LOG_MODULE_NAME (char*) "test"
+    #include <logger.h>
+}
+
+using namespace testing;
+using namespace fuzztest;
+
+constexpr uint32_t max_supported_travel_time = (std::numeric_limits<uint32_t>::max() / 1000) - 1;
+
+// Not completely valid, since the 2 bit qos part in qos_hop_count can be 0
+// or 1. StructOf didn't play well with bitfields so qos and hop count are not
+// separated. Only check first bit for qos when doing assertions.
+auto ValidSingleDataRx() {
+    return StructOf<DataRxIndication>(
+        InRange<uint8_t>(0, 0),                          // indication_status
+        Arbitrary<uint32_t>(),                           // src_add
+        Arbitrary<uint8_t>(),                            // src_endpoint
+        Arbitrary<uint32_t>(),                           // dest_add
+        Arbitrary<uint8_t>(),                            // dest_endpoint
+        Arbitrary<uint8_t>(),                            // qos_hop_count
+        InRange<uint32_t>(0, max_supported_travel_time), // travel_time
+        InRange<uint8_t>(0, 102),                        // apdu_length
+        Arbitrary<std::array<uint8_t, 102>>()            // apdu
+    );
+}
+
+class FuzzUlDataTest
+{
+public:
+    static bool onDataReceived(const uint8_t* bytes,
+                               size_t num_bytes,
+                               app_addr_t src_addr,
+                               app_addr_t dst_addr,
+                               app_qos_e qos,
+                               uint8_t src_ep,
+                               uint8_t dst_ep,
+                               uint32_t travel_time,
+                               uint8_t hop_count,
+                               unsigned long long timestamp_ms_epoch)
+    {
+        last_callback_args = {
+            .bytes { bytes, bytes + num_bytes },
+            .src_addr = src_addr,
+            .dst_addr = dst_addr,
+            .qos = qos,
+            .src_ep = src_ep,
+            .dst_ep = dst_ep,
+            .travel_time = travel_time,
+            .hop_count = hop_count,
+            .timestamp_ms_epoch = timestamp_ms_epoch,
+        };
+        callback_called.release();
+
+        return true;
+    }
+
+    FuzzUlDataTest()
+    {
+        Platform_set_log_level(NO_LOG_LEVEL);
+        WPC_initialize("", 0);
+
+        handler = std::make_shared<QueuedUlDataHandler>();
+        WPC_register_for_data(onDataReceived);
+        serial_stub.AddFrameHandler(0x04, handler);
+    }
+
+    ~FuzzUlDataTest()
+    {
+        WPC_close();
+        serial_stub.ClearFrameHandlers();
+    }
+
+    void TestSingleValidUlMessage(const DataRxIndication& dataRx)
+    {
+        handler->AddToSendQueue(dataRx);
+
+        const uint32_t EXPECTED_TRAVEL_TIME = static_cast<uint64_t>(dataRx.travel_time) * 1000 / 128;
+        const app_qos_e EXPECTED_QOS = static_cast<app_qos_e>(dataRx.qos_hop_count & 0b1);
+        const uint8_t EXPECTED_HOP_COUNT = dataRx.qos_hop_count >> 2;
+
+        ASSERT_TRUE(callback_called.try_acquire_for(std::chrono::seconds(2))) <<
+            "onDataReceived callback wasn't called within the timeout.";
+        ASSERT_TRUE(last_callback_args.has_value());
+        const auto cb_args = last_callback_args.value();
+        last_callback_args.reset();
+
+        ASSERT_EQ(cb_args.bytes.size(), dataRx.apdu_length);
+        ASSERT_EQ(cb_args.src_addr, dataRx.src_add);
+        ASSERT_EQ(cb_args.dst_addr, dataRx.dest_add);
+        ASSERT_EQ(cb_args.src_ep, dataRx.src_endpoint);
+        ASSERT_EQ(cb_args.dst_ep, dataRx.dest_endpoint);
+        ASSERT_EQ(cb_args.travel_time, EXPECTED_TRAVEL_TIME);
+        ASSERT_EQ(cb_args.hop_count, EXPECTED_HOP_COUNT);
+        ASSERT_EQ(cb_args.qos, EXPECTED_QOS);
+    }
+
+    std::shared_ptr<QueuedUlDataHandler> handler;
+    inline static std::binary_semaphore callback_called {0};
+    inline static std::optional<OnDataReceivedArgs> last_callback_args;
+};
+
+
+FUZZ_TEST_F(FuzzUlDataTest, TestSingleValidUlMessage)
+    .WithDomains(ValidSingleDataRx());
+
diff --git a/stubbed_tests/tests/utils/data_structures.h b/stubbed_tests/tests/utils/data_structures.h
new file mode 100644
index 0000000..0c6c3ac
--- /dev/null
+++ b/stubbed_tests/tests/utils/data_structures.h
@@ -0,0 +1,51 @@
+#pragma once
+
+extern "C" {
+    #include <wpc.h>
+}
+#include <array>
+#include <cstdint>
+
+/**
+ * \brief DSAP DATA_RX.indication frame
+ */
+struct [[gnu::packed]] DataRxIndication
+{
+    uint8_t indication_status;
+    uint32_t src_add;
+    uint8_t src_endpoint;
+    uint32_t dest_add;
+    uint8_t dest_endpoint;
+    uint8_t qos_hop_count;
+    uint32_t travel_time;
+    uint8_t apdu_length;
+    std::array<uint8_t, 102> apdu;
+};
+
+/**
+ * \bried Arguments for onDataReceived_cb_f
+ */
+struct OnDataReceivedArgs
+{
+    std::vector<uint8_t> bytes;
+    app_addr_t src_addr;
+    app_addr_t dst_addr;
+    app_qos_e qos;
+    uint8_t src_ep;
+    uint8_t dst_ep;
+    uint32_t travel_time;
+    uint8_t hop_count;
+    unsigned long long timestamp_ms_epoch;
+};
+
+/**
+ * \brief CSAP/DSAP/MSAP-ATTRIBUTE_READ.confirm frame
+ */
+struct [[gnu::packed]] AttributeReadConfirm
+{
+    uint8_t result;
+    uint16_t attribute_id;
+    uint8_t attribute_length;
+    std::array<uint8_t, 16> attribute_value;
+};
+
diff --git a/stubbed_tests/tests/utils/queued_ul_data_handler.cpp b/stubbed_tests/tests/utils/queued_ul_data_handler.cpp
new file mode 100644
index 0000000..31326fe
--- /dev/null
+++ b/stubbed_tests/tests/utils/queued_ul_data_handler.cpp
@@ -0,0 +1,42 @@
+#include "queued_ul_data_handler.h"
+
+#include <cstring>
+#include <serialstub/misc/crc.h>
+
+std::vector<WpcFrame> QueuedUlDataHandler::Handle(const WpcFrame& frame)
+{
+    std::vector<WpcFrame> responses;
+
+    std::lock_guard<std::mutex> lock {to_send_mutex};
+    responses.emplace_back(getConfirm(frame.frame_id, !to_send.empty()));
+
+    for (const auto& rxFrame : to_send)
+    {
+        responses.emplace_back(getDataRxInd(rxFrame, frame.frame_id));
+    }
+    to_send.clear();
+
+    return responses;
+}
+
+WpcFrame QueuedUlDataHandler::getConfirm(const uint8_t frame_id, bool hasIndication)
+{
+    const std::array<uint8_t, 1> payload {hasIndication};
+    return *WpcFrame::Create(0x84, frame_id, payload);
+}
+
+WpcFrame QueuedUlDataHandler::getDataRxInd(const DataRxIndication& rx_frame, const uint8_t frame_id)
+{
+    // Difference from max payload size
+    const auto size_difference = rx_frame.apdu.max_size() - rx_frame.apdu_length;
+    const std::span<const uint8_t> data {reinterpret_cast<const uint8_t*>(&rx_frame),
+                                         sizeof(DataRxIndication) - size_difference};
+    return *WpcFrame::Create(0x03, frame_id, data);
+}
+
+void QueuedUlDataHandler::AddToSendQueue(const DataRxIndication& rxFrame)
+{
+    std::lock_guard<std::mutex> lock {to_send_mutex};
+    to_send.emplace_back(rxFrame);
+}
+
diff --git a/stubbed_tests/tests/utils/queued_ul_data_handler.h b/stubbed_tests/tests/utils/queued_ul_data_handler.h
new file mode 100644
index 0000000..fb76139
--- /dev/null
+++ b/stubbed_tests/tests/utils/queued_ul_data_handler.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include <deque>
+#include <serialstub/frame_handler.h>
+#include <utils/data_structures.h>
+
+/**
+ * \brief FrameHandler for testing uplink data callbacks
+ *
+ * It can be registered for MSAP-INDICATION_POLL.request
+ * Uplink data packet(s) can be added to the queue via AddToSendQueue().
+ * Handle() function returns all of the data packets in the queue and clears the
+ * queue.
+ */
+class QueuedUlDataHandler : public FrameHandler
+{
+public:
+    std::vector<WpcFrame> Handle(const WpcFrame& frame) override;
+    void AddToSendQueue(const DataRxIndication& rxFrame);
+private:
+    WpcFrame getConfirm(const uint8_t frame_id, bool hasIndication);
+    WpcFrame getDataRxInd(const DataRxIndication& rx_frame, const uint8_t frame_id);
+    std::mutex to_send_mutex;
+    std::deque<DataRxIndication> to_send;
+};
+
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 817db28..d5626aa 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -3,9 +3,16 @@ cmake_minimum_required(VERSION 3.18)
 project(meshAPItest LANGUAGES CXX)
 
 set(CMAKE_CXX_STANDARD 17)
-set(CMAKE_BUILD_TYPE RelWithDebInfo)
+if(NOT CMAKE_BUILD_TYPE)
+    set(CMAKE_BUILD_TYPE RelWithDebInfo)
+endif()
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
+set(TEST_EXTRA_CFLAGS "" CACHE STRING "Extra compiler flags for WPC library and test code. For example '--coverage'.")
+set(TEST_EXTRA_LDFLAGS "" CACHE STRING "Extra linker flags for the test executable. For example '--coverage'.")
+separate_arguments(TEST_EXTRA_CFLAGS)
+separate_arguments(TEST_EXTRA_LDFLAGS)
+
 add_compile_options(-Wall -Werror -Wextra)
 
 set(WPC_LIB_DIR "${CMAKE_CURRENT_LIST_DIR}/../lib/")
@@ -42,3 +49,8 @@ target_link_libraries(${CMAKE_PROJECT_NAME}
 include(GoogleTest)
 gtest_discover_tests(${CMAKE_PROJECT_NAME})
 
+target_compile_options(wpc                   PRIVATE ${TEST_EXTRA_CFLAGS})
+target_compile_options(wpc_platform          PRIVATE ${TEST_EXTRA_CFLAGS})
+target_compile_options(${CMAKE_PROJECT_NAME} PRIVATE ${TEST_EXTRA_CFLAGS})
+target_link_options(${CMAKE_PROJECT_NAME} PRIVATE ${TEST_EXTRA_LDFLAGS})
+
diff --git a/test/otap_files/dummy.otap b/test/otap_files/dummy.otap
deleted file mode 100644
index 77e48ea..0000000
Binary files a/test/otap_files/dummy.otap and /dev/null differ
diff --git a/test/scratchpad_tests.cpp b/test/scratchpad_tests.cpp
index bbd8903..f1bc53c 100644
--- a/test/scratchpad_tests.cpp
+++ b/test/scratchpad_tests.cpp
@@ -1,5 +1,3 @@
-#include <fstream>
-#include <filesystem>
 #include <gtest/gtest.h>
 #include "wpc_test.hpp"
 
@@ -11,27 +9,30 @@ class WpcScratchpadTest : public WpcTest
         ASSERT_NO_FATAL_FAILURE(WpcTest::SetUpTestSuite());
         ASSERT_NO_FATAL_FAILURE(WpcTest::StopStack());
         ASSERT_EQ(APP_RES_OK, WPC_set_role(APP_ROLE_SINK));
-        ASSERT_TRUE(std::filesystem::exists(OTAP_UPLOAD_FILE_PATH));
     }
 
 protected:
-    inline static const std::filesystem::path OTAP_UPLOAD_FILE_PATH = "otap_files/dummy.otap";
-
-    std::vector<uint8_t> ReadUploadFile() const
-    {
-        const auto size = std::filesystem::file_size(OTAP_UPLOAD_FILE_PATH);
-        std::vector<uint8_t> buffer(size);
-
-        if (std::ifstream ifs(OTAP_UPLOAD_FILE_PATH, std::ios_base::binary); ifs) {
-            if (ifs.read((char*)buffer.data(), size)) {
-                return buffer;
-            }
-        }
-
-        ADD_FAILURE() << "Cannot open file " << OTAP_UPLOAD_FILE_PATH << ". "
-                      << "Please update OTAP_UPLOAD_FILE_PATH to a valid OTAP image";
-        return {};
-    }
+    inline static const std::vector<uint8_t> DUMMY_SCRATCHPAD = {
+        0x53, 0x43, 0x52, 0x31, 0x9a, 0x93, 0x30, 0x82, 0xd9, 0xeb, 0x0a,
+        0xfc, 0x31, 0x21, 0xe3, 0x37, 0xb0, 0x00, 0x00, 0x00, 0x33, 0x6c,
+        0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff,
+        0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
+        0xff, 0xff, 0xff, 0xff, 0x53, 0x43, 0x52, 0x31, 0x9a, 0x93, 0x30,
+        0x82, 0xd9, 0xeb, 0x0a, 0xfc, 0x31, 0x21, 0xe3, 0x37, 0x80, 0x00,
+        0x00, 0x00, 0x0b, 0x27, 0xff, 0x00, 0x00, 0x00, 0x00, 0x00, 0xff,
+        0xff, 0xff, 0xff, 0xaf, 0x29, 0xd6, 0xc6, 0x09, 0xfd, 0x8f, 0x78,
+        0xba, 0xb5, 0xc4, 0x2f, 0x43, 0x6d, 0xf1, 0xcd, 0xd4, 0x6a, 0x0d,
+        0xa3, 0x1a, 0x8c, 0xcb, 0xd9, 0xf0, 0xf9, 0xb1, 0xdf, 0x4a, 0xef,
+        0x1e, 0x8b, 0x00, 0x00, 0x00, 0x00, 0x50, 0x00, 0x00, 0x00, 0x00,
+        0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0xa4, 0xae, 0xab, 0x5b,
+        0xce, 0x4c, 0x4a, 0x45, 0xda, 0x77, 0xe2, 0x48, 0xd2, 0x03, 0x62,
+        0x79, 0xf9, 0x98, 0xc2, 0xa1, 0x0a, 0x8e, 0x15, 0x5b, 0x21, 0x12,
+        0xbe, 0x2e, 0x5e, 0x79, 0x16, 0xd4, 0x58, 0xaf, 0x83, 0x74, 0x6e,
+        0x9a, 0x7c, 0x0e, 0x26, 0xcd, 0x5d, 0xf6, 0xc7, 0xa5, 0x40, 0x4e,
+        0xb9, 0xc3, 0x5c, 0x02, 0x62, 0xab, 0xdb, 0x21, 0xc3, 0x7e, 0x64,
+        0xe9, 0xcc, 0x95, 0xb2, 0x34, 0x5e, 0xab, 0xd0, 0x7f, 0x5e, 0xe2,
+        0x26, 0x8c, 0x3f, 0x6b, 0xc7, 0xc6, 0x33, 0x04, 0x83, 0x6e
+    };
 
     void UploadScratchpadAndVerify(const std::vector<uint8_t>& buffer, const uint8_t seq_number) const
     {
@@ -77,8 +78,7 @@ class WpcScratchpadTest : public WpcTest
 
 TEST_F(WpcScratchpadTest, testUploadAndClearScratchpad)
 {
-    const auto buffer = ReadUploadFile();
-    ASSERT_NO_FATAL_FAILURE(UploadScratchpadAndVerify(buffer, 101));
+    ASSERT_NO_FATAL_FAILURE(UploadScratchpadAndVerify(DUMMY_SCRATCHPAD, 101));
 
     ASSERT_EQ(APP_RES_OK, WPC_clear_local_scratchpad());
 
@@ -97,7 +97,7 @@ TEST_F(WpcScratchpadTest, testUploadAndClearScratchpad)
 
 TEST_F(WpcScratchpadTest, testUploadAndDownloadScratchpadInBlocks)
 {
-    const auto upload_buffer = ReadUploadFile();
+    const auto& upload_buffer = DUMMY_SCRATCHPAD;
 
     const uint32_t MAX_BLOCK_SIZE = 32;
     ASSERT_LT(MAX_BLOCK_SIZE, upload_buffer.size());
@@ -139,7 +139,7 @@ TEST_F(WpcScratchpadTest, testUploadAndDownloadScratchpadInBlocks)
 
 TEST_F(WpcScratchpadTest, testUploadAndDownloadScratchpad)
 {
-    auto upload_buffer = ReadUploadFile();
+    const auto& upload_buffer = DUMMY_SCRATCHPAD;
     ASSERT_NO_FATAL_FAILURE(UploadScratchpadAndVerify(upload_buffer, 201));
 
     std::vector<uint8_t> download_buffer(upload_buffer.size());