Unit Testing in ESP32
=============================
:link_to_translation:`zh_CN:[中文]`

ESP-IDF comes with a unit test application that is based on the Unity - unit test framework. Unit tests are integrated in the ESP-IDF repository and are placed in the ``test`` subdirectories of each component respectively.

Normal Test Cases
------------------

Unit tests are located in the ``test`` subdirectory of a component.
Tests are written in C, and a single C source file can contain multiple test cases.
Test files start with the word "test".

Each test file should include the ``unity.h`` header and the header for the C module to be tested.

Tests are added in a function in the C file as follows:

.. code-block:: c

    TEST_CASE("test name", "[module name]"
    {
            // Add test here
    }

The first argument is a descriptive name for the test, the second argument is an identifier in square brackets.
Identifiers are used to group related test, or tests with specific properties.

.. note:: 
    There is no need to add a main function with ``UNITY_BEGIN()`` and ``​UNITY_END()`` in each test case. ``unity_platform.c`` will run ``UNITY_BEGIN()`` autonomously, and run the test cases, then call ``​UNITY_END()``.

The ``test`` subdirectory should contain a :ref:`component CMakeLists.txt <component-directories>`, since they are themselves, components. ESP-IDF uses the ``unity`` test framework and should be specified as a requirement for the component. Normally, components :ref:`should list their sources manually <cmake-file-globbing>`; for component tests however, this requirement is relaxed and the use of the ``SRC_DIRS`` argument in ``idf_component_register`` is advised.

Overall, the minimal ``test`` subdirectory ``CMakeLists.txt`` file should contain the following:

.. code:: cmake

    idf_component_register(SRC_DIRS "."
                           INCLUDE_DIRS "."
                           REQUIRES unity)

See http://www.throwtheswitch.org/unity for more information about writing tests in Unity.


Multi-device Test Cases
-------------------------

The normal test cases will be executed on one DUT (Device Under Test). However, components that require some form of communication (e.g., GPIO, SPI) require another device to communicate with, thus cannot be tested normal test cases.
Multi-device test cases involve writing multiple test functions, and running them on multiple DUTs.

The following is an example of a multi-device test case:

.. code-block:: c

    void gpio_master_test()
    {
        gpio_config_t slave_config = {
                .pin_bit_mask = 1 << MASTER_GPIO_PIN,
                .mode = GPIO_MODE_INPUT,
        };
        gpio_config(&slave_config);
        unity_wait_for_signal("output high level");
        TEST_ASSERT(gpio_get_level(MASTER_GPIO_PIN) == 1);
    }

    void gpio_slave_test()
    {
        gpio_config_t master_config = {
                .pin_bit_mask = 1 << SLAVE_GPIO_PIN,
                .mode = GPIO_MODE_OUTPUT,
        };
        gpio_config(&master_config);
        gpio_set_level(SLAVE_GPIO_PIN, 1);
        unity_send_signal("output high level");
    }

    TEST_CASE_MULTIPLE_DEVICES("gpio multiple devices test example", "[driver]", gpio_master_test, gpio_slave_test);


The macro ``TEST_CASE_MULTIPLE_DEVICES`` is used to declare a multi-device test case.
The first argument is test case name, the second argument is test case description.
From the third argument, up to 5 test functions can be defined, each function will be the entry point of tests running on each DUT.

Running test cases from different DUTs could require synchronizing between DUTs. We provide ``unity_wait_for_signal`` and ``unity_send_signal`` to support synchronizing with UART.
As the scenario in the above example, the slave should get GPIO level after master set level. DUT UART console will prompt and user interaction is required:

DUT1 (master) console::

    Waiting for signal: [output high level]!
    Please press "Enter" key to once any board send this signal.

DUT2 (slave) console::

    Send signal: [output high level]!

Once the signal is sent from DUT2, you need to press "Enter" on DUT1, then DUT1 unblocks from ``unity_wait_for_signal`` and starts to change GPIO level.


Multi-stage Test Cases
-----------------------

The normal test cases are expected to finish without reset (or only need to check if reset happens). Sometimes we expect to run some specific tests after certain kinds of reset. 
For example, we expect to test if the reset reason is correct after a wakeup from deep sleep. We need to create a deep-sleep reset first and then check the reset reason.
To support this, we can define multi-stage test cases, to group a set of test functions::

    static void trigger_deepsleep(void)
    {
        esp_sleep_enable_timer_wakeup(2000);
        esp_deep_sleep_start();
    }

    void check_deepsleep_reset_reason()
    {
        RESET_REASON reason = rtc_get_reset_reason(0);
        TEST_ASSERT(reason == DEEPSLEEP_RESET);
    }

    TEST_CASE_MULTIPLE_STAGES("reset reason check for deepsleep", "[esp32]", trigger_deepsleep, check_deepsleep_reset_reason);

Multi-stage test cases present a group of test functions to users. It needs user interactions (select cases and select different stages) to run the case.


Building Unit Test App
----------------------

Follow the setup instructions in the top-level esp-idf README.
Make sure that ``IDF_PATH`` environment variable is set to point to the path of esp-idf top-level directory.

Change into ``tools/unit-test-app`` directory to configure and build it:

* ``idf.py menuconfig`` - configure unit test app.

* ``idf.py -T all build`` - build unit test app with tests for each component having tests in the ``test`` subdirectory.
* ``idf.py -T "xxx yyy" build`` - build unit test app with tests for some space-separated specific components (For instance: ``idf.py -T heap build`` - build unit tests only for ``heap`` component directory).
* ``idf.py -T all -E "xxx yyy" build`` - build unit test app with all unit tests, except for unit tests of some components (For instance: ``idf.py -T all -E "ulp mbedtls" build`` - build all unit tests excluding ``ulp`` and ``mbedtls`` components).

When the build finishes, it will print instructions for flashing the chip. You can simply run ``idf.py flash`` to flash all build output.

You can also run ``idf.py -T all flash`` or ``idf.py -T xxx flash`` to build and flash. Everything needed will be rebuilt automatically before flashing. 

Use menuconfig to set the serial port for flashing.

Running Unit Tests
------------------

After flashing reset the ESP32 and it will boot the unit test app.

When unit test app is idle, press "Enter" will make it print test menu with all available tests::

    Here's the test menu, pick your combo:
    (1)     "esp_ota_begin() verifies arguments" [ota]
    (2)     "esp_ota_get_next_update_partition logic" [ota]
    (3)     "Verify bootloader image in flash" [bootloader_support]
    (4)     "Verify unit test app image" [bootloader_support]
    (5)     "can use new and delete" [cxx]
    (6)     "can call virtual functions" [cxx]
    (7)     "can use static initializers for non-POD types" [cxx]
    (8)     "can use std::vector" [cxx]
    (9)     "static initialization guards work as expected" [cxx]
    (10)    "global initializers run in the correct order" [cxx]
    (11)    "before scheduler has started, static initializers work correctly" [cxx]
    (12)    "adc2 work with wifi" [adc]
    (13)    "gpio master/slave test example" [ignore][misc][test_env=UT_T2_1][multi_device]
            (1)     "gpio_master_test"
            (2)     "gpio_slave_test"
    (14)    "SPI Master clockdiv calculation routines" [spi]
    (15)    "SPI Master test" [spi][ignore]
    (16)    "SPI Master test, interaction of multiple devs" [spi][ignore]
    (17)    "SPI Master no response when switch from host1 (HSPI) to host2 (VSPI)" [spi]
    (18)    "SPI Master DMA test, TX and RX in different regions" [spi]
    (19)    "SPI Master DMA test: length, start, not aligned" [spi]
    (20)    "reset reason check for deepsleep" [esp32][test_env=UT_T2_1][multi_stage]
            (1)     "trigger_deepsleep"
            (2)     "check_deepsleep_reset_reason"

The normal case will print the case name and description. Master-slave cases will also print the sub-menu (the registered test function names).

Test cases can be run by inputting one of the following:

- Test case name in quotation marks to run a single test case 

- Test case index to run a single test case

- Module name in square brackets to run all test cases for a specific module

- An asterisk to run all test cases

``[multi_device]`` and ``[multi_stage]`` tags tell the test runner whether a test case is a multiple devices or multiple stages of test case.
These tags are automatically added by ```TEST_CASE_MULTIPLE_STAGES`` and ``TEST_CASE_MULTIPLE_DEVICES`` macros.

After you select a multi-device test case, it will print sub-menu::

    Running gpio master/slave test example...
    gpio master/slave test example
            (1)     "gpio_master_test"
            (2)     "gpio_slave_test"

You need to input a number to select the test running on the DUT.

Similar to multi-device test cases, multi-stage test cases will also print sub-menu::

    Running reset reason check for deepsleep...
    reset reason check for deepsleep
            (1)     "trigger_deepsleep"
            (2)     "check_deepsleep_reset_reason"


First time you execute this case, input ``1`` to run first stage (trigger deepsleep).
After DUT is rebooted and able to run test cases, select this case again and input ``2`` to run the second stage.
The case only passes if the last stage passes and all previous stages trigger reset.


Timing Code with Cache Compensated Timer
-----------------------------------------

Instructions and data stored in external memory (e.g. SPI Flash and SPI RAM) are accessed through the CPU's unified instruction and data cache. When code or data is in cache, access is very fast (i.e., a cache hit).

However, if the instruction or data is not in cache, it needs to be fetched from external memory (i.e., a cache miss). Access to external memory is significantly slower, as the CPU must execute stall cycles whilst waiting for the instruction or data to be retrieved from external memory. This can cause the overall code execution speed to vary depending on the number of cache hits or misses.

Code and data placements can vary between builds, and some arrangements may be more favorable with regards to cache access (i.e., minimizing cache misses). This can technically affect execution speed, however these factors are usually irrelevant as their effect 'average out' over the device's operation.

The effect of the cache on execution speed, however, can be relevant in benchmarking scenarios (espcially microbenchmarks). There might be some variability in measured time
between runs and between different builds. A technique for eliminating for some of the
variability is to place code and data in instruction or data RAM (IRAM/DRAM), respectively. The CPU can access IRAM and DRAM directly, eliminating the cache out of the equation.
However, this might not always be viable as the size of IRAM and DRAM is limited.

The cache compensated timer is an alternative to placing the code/data to be benchmarked in IRAM/DRAM. This timer uses the processor's internal event counters in order to determine the amount 
of time spent on waiting for code/data in case of a cache miss, then subtract that from the recorded wall time. 

  .. code-block:: c

    // Start the timer
    ccomp_timer_start();

    // Function to time
    func_code_to_time();

    // Stop the timer, and return the elapsed time in microseconds relative to
    // ccomp_timer_start
    int64_t t = ccomp_timer_stop();


One limitation of the cache compensated timer is that the task that benchmarked functions should be pinned to a core. This is due to each core having its own event counters that are independent of each other. For example, if ``ccomp_timer_start`` gets called on one core, put to sleep by the scheduler, wakes up, and gets rescheduled on the other core, then the corresponding ``ccomp_timer_stop`` will be invalid.
invalid.

