Unit Testing in ESP32

ESP-IDF comes with a unit test app based on Unity - unit test framework. Unit tests are integrated in the ESP-IDF repository and are placed in test subdirectory of each component respectively.

Add normal test cases

Unit tests are added in the test subdirectory of the respective component. Tests are added in C files, a single C file can include multiple test cases. Test files start with the word “test”.

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

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

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

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

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(), run the tests cases, and then call ​UNITY_END().

Each test subdirectory needs to include component.mk file with at least the following line of code:

COMPONENT_ADD_LDFLAGS = -Wl,--whole-archive -l$(COMPONENT_NAME) -Wl,--no-whole-archive

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

Add multiple devices test cases

The normal test cases will be executed on one DUT (Device Under Test). Components need to communicate with each other (like GPIO, SPI …) can’t be tested with normal test cases. Multiple devices test cases support writing and running test with multiple DUTs.

Here’s an example of multiple devices test case:

void gpio_master_test()
    gpio_config_t slave_config = {
            .pin_bit_mask = 1 << MASTER_GPIO_PIN,
            .mode = GPIO_MODE_INPUT,
    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_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 multiple devices test cases. First argument is test case name, second argument is test case description. From the third argument, upto 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 secnario in the above example, slave should get GPIO level after master set level. DUT UART console will prompt and requires user interaction:

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 set from DUT2, you need to press “Enter” on DUT1, then DUT1 unblocks from unity_wait_for_signal and starts to change GPIO level.

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:

  • make menuconfig - configure unit test app.
  • make TESTS_ALL=1 - build unit test app with tests for each component having tests in the test subdirectory.
  • make TEST_COMPONENTS=’xxx’ - build unit test app with tests for specific components.

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

You can also run make flash TESTS_ALL=1 or make TEST_COMPONENTS='xxx' 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]
        (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]

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

After you select multiple devices 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 number to select the test running on the DUT.