KUnit

Unit testing framework for the kernel.

Basic Test Structure

#include <kunit/test.h>

/* Test case */
static void my_test_addition(struct kunit *test)
{
    int result = my_add(2, 3);
    KUNIT_EXPECT_EQ(test, result, 5);
}

static void my_test_null_check(struct kunit *test)
{
    void *ptr = my_alloc(0);
    KUNIT_EXPECT_NULL(test, ptr);
}

/* Test suite */
static struct kunit_case my_test_cases[] = {
    KUNIT_CASE(my_test_addition),
    KUNIT_CASE(my_test_null_check),
    {}
};

static struct kunit_suite my_test_suite = {
    .name = "my_driver_tests",
    .test_cases = my_test_cases,
};
kunit_test_suite(my_test_suite);

MODULE_LICENSE("GPL");

Assertions

Macro	Checks
KUNIT_EXPECT_EQ(test, a, b)	a == b
KUNIT_EXPECT_NE(test, a, b)	a != b
KUNIT_EXPECT_LT(test, a, b)	a < b
KUNIT_EXPECT_TRUE(test, cond)	condition true
KUNIT_EXPECT_NULL(test, ptr)	ptr is NULL
KUNIT_EXPECT_NOT_ERR_OR_NULL(test, ptr)	valid pointer

EXPECT continues on failure; ASSERT stops test.

Setup/Teardown

static int my_test_init(struct kunit *test)
{
    struct my_context *ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL);
    test->priv = ctx;
    return 0;  /* 0 = success */
}

static void my_test_exit(struct kunit *test)
{
    /* kunit_kzalloc auto-freed */
}

static struct kunit_suite my_suite = {
    .name = "my_tests",
    .init = my_test_init,
    .exit = my_test_exit,
    .test_cases = my_test_cases,
};

Running Tests

# Build with KUnit
./tools/testing/kunit/kunit.py run --kunitconfig=drivers/my_driver/.kunitconfig

# Or as module
insmod my_test.ko
# Results in dmesg

# Parse results
dmesg | grep -A 100 'my_driver_tests'

Test Organization

drivers/my_driver/
├── my_driver.c
├── my_driver_test.c    # KUnit tests
├── Kconfig
├── Makefile
└── .kunitconfig        # KUnit config

.kunitconfig:

CONFIG_KUNIT=y
CONFIG_MY_DRIVER=y
CONFIG_MY_DRIVER_KUNIT_TEST=y

Summary

1. Create test functions with KUNIT_EXPECT_*
2. Group in kunit_case array
3. Define kunit_suite
4. Register with kunit_test_suite()
5. Run with kunit.py or as module

Further Reading

• KUnit Documentation
• Writing Tests