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Writing tests for OpenSBI

SBIUnit

SBIUnit is a set of macros and functions which simplify the test development and automate the test execution and evaluation. All of the SBIUnit definitions are in the include/sbi/sbi_unit_test.h header file, and implementations are available in lib/sbi/tests/sbi_unit_test.c.

Simple SBIUnit test

For instance, we would like to test the following function from lib/sbi/sbi_string.c:

size_t sbi_strlen(const char *str)
{
	unsigned long ret = 0;

	while (*str != '\0') {
		ret++;
		str++;
	}

	return ret;
}

which calculates the string length.

Create the file lib/sbi/tests/sbi_string_test.c with the following content:

#include <sbi/sbi_unit_test.h>
#include <sbi/sbi_string.h>

static void strlen_test(struct sbiunit_test_case *test)
{
	SBIUNIT_EXPECT_EQ(test, sbi_strlen("Hello"), 5);
	SBIUNIT_EXPECT_EQ(test, sbi_strlen("Hell\0o"), 4);
}

static struct sbiunit_test_case string_test_cases[] = {
	SBIUNIT_TEST_CASE(strlen_test),
	SBIUNIT_END_CASE,
};

SBIUNIT_TEST_SUITE(string_test_suite, string_test_cases);

Then, add the corresponding Makefile entries to lib/sbi/tests/objects.mk:

...
carray-sbi_unit_tests-$(CONFIG_SBIUNIT) += string_test_suite
libsbi-objs-$(CONFIG_SBIUNIT) += tests/sbi_string_test.o

Now, run make clean in order to regenerate the carray-related files.

Recompile OpenSBI with the CONFIG_SBIUNIT option enabled and run it in QEMU. You will see something like this:

# make PLATFORM=generic run
...
# Running SBIUNIT tests #
...
## Running test suite: string_test_suite
[PASSED] strlen_test
1 PASSED / 0 FAILED / 1 TOTAL

Now let's try to change this test in the way that it will fail:

- SBIUNIT_EXPECT_EQ(test, sbi_strlen("Hello"), 5);
+ SBIUNIT_EXPECT_EQ(test, sbi_strlen("Hello"), 100);

make all and make run it again:

...
# Running SBIUNIT tests #
...
## Running test suite: string_test_suite
[SBIUnit] [.../opensbi/lib/sbi/tests/sbi_string_test.c:6]: strlen_test: Condition "(sbi_strlen("Hello")) == (100)" expected to be true!
[FAILED] strlen_test
0 PASSED / 1 FAILED / 1 TOTAL

Covering the static functions / using the static definitions

SBIUnit also allows you to test static functions. In order to do so, simply include your test source in the file you would like to test. Complementing the example above, just add this to the lib/sbi/sbi_string.c file:

#ifdef CONFIG_SBIUNIT
#include "tests/sbi_string_test.c"
#endif

In this case you should only add a new carray entry pointing to the test suite to lib/sbi/tests/objects.mk:

...
carray-sbi_unit_tests-$(CONFIG_SBIUNIT) += string_test_suite

You don't have to compile the sbi_string_test.o separately, because the test code will be included into the sbi_string object file.

"Mocking" the structures

See the example of structure "mocking" in lib/sbi/tests/sbi_console_test.c, where the sbi_console_device structure was mocked to be used in various console-related functions in order to test them.

API Reference

All of the SBIUNIT_EXPECT_* macros will cause a test case to fail if the corresponding conditions are not met, however, the execution of a particular test case will not be stopped.

All of the SBIUNIT_ASSERT_* macros will cause a test case to fail and stop immediately, triggering a panic.

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