STRUCT KUNIT_CASE(9)

💅 struct kunit_case(9) — Kernel API Manual, bestie edition 🎀

Okay so this is a page from the Kernel API Manual (struct kunit_case(9)), and honestly? It's giving "the building block of every KUnit test you'll ever write." Let's get into it ✨

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🌸 NAME 🌸

struct kunit_case — the glow-up container that represents, like, one individual test case. Just one. A whole little icon. 👑

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✨ SYNOPSIS ✨

struct kunit_case {
    void (*run_case)(struct kunit *test);
    const char *name;
    const void* (*generate_params)(struct kunit *test, const void *prev,
char *desc);
    struct kunit_attributes attr;
    int (*param_init)(struct kunit *test);
    void (*param_exit)(struct kunit *test);
 };

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🦋 Members 🦋

• run_case — the actual function doing the test-case thing. This is the main character, no cap.
• name — what the test case is called. Its little nametag at the party 🎀
• generate_params — the generator function for parameterized tests. iykyk 💫
• attr — the attributes hanging out with the test.
• param_init — the init function that runs before a parameterized test.
• param_exit — the exit function that runs after a parameterized test. Cleanup queen 🧹

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💖 Description 💖

So a test case is literally just a function with the signature void (*)(struct kunit *) that makes expectations and assertions (see KUNIT_EXPECT_TRUE and KUNIT_ASSERT_TRUE) about the code under test. That's the whole vibe check: you point it at some code and you assert stuff about it.

Each test case is associated with a struct kunit_suite, and it gets run after the suite's init function and followed by the suite's exit function. Like a little sandwich 🥪

Bestie, listen: a test case should be static, and it should only be created with the KUNIT_CASE macro. Also — and this is the part people forget 😭 — every array of test cases must be terminated with an empty test case. Do not skip the empty one. It's the periodt of the array.

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🌈 Example 🌈

void add_test_basic(struct kunit *test)
{
        KUNIT_EXPECT_EQ(test, 1, add(1, 0));
        KUNIT_EXPECT_EQ(test, 2, add(1, 1));
        KUNIT_EXPECT_EQ(test, 0, add(-1, 1));
        KUNIT_EXPECT_EQ(test, INT_MAX, add(0, INT_MAX));
        KUNIT_EXPECT_EQ(test, -1, add(INT_MAX, INT_MIN));
}

static struct kunit_case example_test_cases[] = {
        KUNIT_CASE(add_test_basic),
        {}
};

See that {} at the end? That's the empty test case terminator doing its job. Obsessed. 💅

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🫶 SEE ALSO 🫶

The kernel file is ./include/kunit/test.h, and honestly the whole friend group is here:

enum kunit_status(9), KUNIT_CASE(9), KUNIT_CASE_ATTR(9), KUNIT_CASE_SLOW(9), KUNIT_CASE_PARAM(9), KUNIT_CASE_PARAM_ATTR(9), KUNIT_CASE_PARAM_WITH_INIT(9), struct kunit_suite(9), struct kunit(9), kunit_test_suites(9), kunit_test_init_section_suites(9), kunit_kmalloc_array(9), kunit_kmalloc(9), kunit_kfree(9), kunit_kzalloc(9), kunit_kcalloc(9), kunit_kfree_const(9), kunit_kstrdup(9), kunit_kstrdup_const(9), kunit_attach_mm(9), kunit_vm_mmap(9), kunit_mark_skipped(9), kunit_skip(9), kunit_info(9), kunit_warn(9), kunit_err(9), KUNIT_SUCCEED(9), KUNIT_FAIL(9), KUNIT_EXPECT_TRUE(9), KUNIT_EXPECT_FALSE(9), KUNIT_EXPECT_EQ(9), KUNIT_EXPECT_PTR_EQ(9), KUNIT_EXPECT_NE(9), KUNIT_EXPECT_PTR_NE(9), KUNIT_EXPECT_LT(9), KUNIT_EXPECT_LE(9), KUNIT_EXPECT_GT(9), KUNIT_EXPECT_GE(9), KUNIT_EXPECT_STREQ(9), KUNIT_EXPECT_STRNEQ(9), KUNIT_EXPECT_MEMEQ(9), KUNIT_EXPECT_MEMNEQ(9), KUNIT_EXPECT_NULL(9), KUNIT_EXPECT_NOT_NULL(9), KUNIT_EXPECT_NOT_ERR_OR_NULL(9), KUNIT_FAIL_AND_ABORT(9), KUNIT_ASSERT_TRUE(9), KUNIT_ASSERT_FALSE(9), KUNIT_ASSERT_EQ(9), KUNIT_ASSERT_PTR_EQ(9), KUNIT_ASSERT_NE(9), KUNIT_ASSERT_PTR_NE(9), KUNIT_ASSERT_LT(9), KUNIT_ASSERT_LE(9), KUNIT_ASSERT_GT(9), KUNIT_ASSERT_GE(9), KUNIT_ASSERT_STREQ(9), KUNIT_ASSERT_STRNEQ(9), KUNIT_ASSERT_MEMEQ(9), KUNIT_ASSERT_MEMNEQ(9), KUNIT_ASSERT_NULL(9), KUNIT_ASSERT_NOT_NULL(9), KUNIT_ASSERT_NOT_ERR_OR_NULL(9), KUNIT_ARRAY_PARAM(9), KUNIT_ARRAY_PARAM_DESC(9), kunit_register_params_array(9), kunit_warning_suppress(9), KUNIT_SUPPRESSED_WARNING_COUNT(9), KUNIT_EXPECT_SUPPRESSED_WARNING_COUNT(9), KUNIT_ASSERT_SUPPRESSED_WARNING_COUNT(9).

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💖 That's the whole page, bestie! 💖 This cutie came from ./include/kunit and it's dated October 2026 — so yeah, timestamped and slaying. 🦋🌸 Go write some tests, mwah 💅✨