tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
fork
Configure Feed
Select the types of activity you want to include in your feed.
1.. SPDX-License-Identifier: GPL-2.0
2
3==========================
4Frequently Asked Questions
5==========================
6
7How is this different from Autotest, kselftest, etc?
8====================================================
9KUnit is a unit testing framework. Autotest, kselftest (and some others) are
10not.
11
12A `unit test <https://martinfowler.com/bliki/UnitTest.html>`_ is supposed to
13test a single unit of code in isolation, hence the name. A unit test should be
14the finest granularity of testing and as such should allow all possible code
15paths to be tested in the code under test; this is only possible if the code
16under test is very small and does not have any external dependencies outside of
17the test's control like hardware.
18
19There are no testing frameworks currently available for the kernel that do not
20require installing the kernel on a test machine or in a VM and all require
21tests to be written in userspace and run on the kernel under test; this is true
22for Autotest, kselftest, and some others, disqualifying any of them from being
23considered unit testing frameworks.
24
25Does KUnit support running on architectures other than UML?
26===========================================================
27
28Yes, well, mostly.
29
30For the most part, the KUnit core framework (what you use to write the tests)
31can compile to any architecture; it compiles like just another part of the
32kernel and runs when the kernel boots, or when built as a module, when the
33module is loaded. However, there is some infrastructure,
34like the KUnit Wrapper (``tools/testing/kunit/kunit.py``) that does not support
35other architectures.
36
37In short, this means that, yes, you can run KUnit on other architectures, but
38it might require more work than using KUnit on UML.
39
40For more information, see :ref:`kunit-on-non-uml`.
41
42What is the difference between a unit test and these other kinds of tests?
43==========================================================================
44Most existing tests for the Linux kernel would be categorized as an integration
45test, or an end-to-end test.
46
47- A unit test is supposed to test a single unit of code in isolation, hence the
48 name. A unit test should be the finest granularity of testing and as such
49 should allow all possible code paths to be tested in the code under test; this
50 is only possible if the code under test is very small and does not have any
51 external dependencies outside of the test's control like hardware.
52- An integration test tests the interaction between a minimal set of components,
53 usually just two or three. For example, someone might write an integration
54 test to test the interaction between a driver and a piece of hardware, or to
55 test the interaction between the userspace libraries the kernel provides and
56 the kernel itself; however, one of these tests would probably not test the
57 entire kernel along with hardware interactions and interactions with the
58 userspace.
59- An end-to-end test usually tests the entire system from the perspective of the
60 code under test. For example, someone might write an end-to-end test for the
61 kernel by installing a production configuration of the kernel on production
62 hardware with a production userspace and then trying to exercise some behavior
63 that depends on interactions between the hardware, the kernel, and userspace.