TEST_F(9)

💅 TEST_F(9) — the kselftest harness glow-up, fixture edition

okay so bestie, real talk: this is a page from the Kernel API Manual, and it's literally about TEST_F. yes, that TEST_F. the fixture-based test case one. buckle up 🎀

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✨ NAME ✨

TEST_F — emits test registration and helpers for fixture-based test cases. that's the whole vibe, no notes 💖

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🦋 SYNOPSIS 🦋

TEST_F (fixture_name , test_name );

yes that's the whole call. two arguments, no cap. 🔥

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🌸 ARGUMENTS 🌸

• fixture_name — the fixture name. that's it, that's the girl 🫶
• test_name — the test name. also exactly what it sounds like ✨

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👑 DESCRIPTION 👑

so here's the shape of it, and it's giving iconic:

TEST_F(fixture, name) { implementation }

what this does is defines a test that depends on a fixture (like, it's part of a test case, iykyk). it's very similar to TEST, except — and this is the main character moment — self is the setup instance of the fixture's datatype, exposed for use by the implementation. so your implementation gets to just... use it. slay. 💅

now for the slightly unhinged but extremely important part, so pay attention bestie:

the _metadata object is shared (MAP_SHARED) with all the potential forked processes, which enables them to use EXCEPT_*() and ASSERT_*(). shared memory, shared dreams, fr fr 🌈

but the self object? that one is only shared with the potential forked processes if FIXTURE_TEARDOWN_PARENT is used instead of FIXTURE_TEARDOWN. so like. vibe check your teardown choice, okay? because that's literally the difference. 😭

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🔮 SEE ALSO 🔮

the whole squad, and yes, we're listing every single one, because none of them are getting left on read:

• the Kernel file ./tools/testing/selftests/kselftest_harness.h (the source of truth, the blueprint, the moment) and example(9)
• TH_LOG(9), SKIP(9), TEST(9), TEST_SIGNAL(9)
• FIXTURE_DATA(9), FIXTURE(9)
• FIXTURE_SETUP(9), FIXTURE_TEARDOWN(9), FIXTURE_TEARDOWN_PARENT(9)
• FIXTURE_VARIANT(9), FIXTURE_VARIANT_ADD(9)
• TEST_HARNESS_MAIN(9), operators(9)
• ASSERT_EQ(9), ASSERT_NE(9), ASSERT_LT(9), ASSERT_LE(9), ASSERT_GT(9), ASSERT_GE(9), ASSERT_NULL(9), ASSERT_TRUE(9), ASSERT_FALSE(9), ASSERT_STREQ(9), ASSERT_STRNE(9)
• EXPECT_EQ(9), EXPECT_NE(9), EXPECT_LT(9), EXPECT_LE(9), EXPECT_GT(9), EXPECT_GE(9), EXPECT_NULL(9), EXPECT_TRUE(9), EXPECT_FALSE(9), EXPECT_STREQ(9), EXPECT_STRNE(9)
• XFAIL_ADD(9)

like... that's the whole friend group and they ALL showed up 💜

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ok and one last thing before you go — this page lives at ./tools/testing/selftests, it's dated October 2026, and it's page TEST_F(9) of the Kernel API Manual. write it down, screenshot it, tattoo it, whatever. mwah 💋 🌸 🧚‍♀️