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.
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.
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.
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:
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.
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::
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.
*``idf.py -T all build`` - build unit test app with tests for each component having tests in the ``test`` subdirectory.
*``idf.py -T xxx build`` - build unit test app with tests for specific components.
*``idf.py -T all -E xxxbuild`` - 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 exludes ``ulp`` and ``mbedtls`` components).
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.
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.
