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c23a283b53
Add documentation for KUnit, the Linux kernel unit testing framework. - Add intro and usage guide for KUnit - Add API reference Signed-off-by: Felix Guo <felixguoxiuping@gmail.com> Signed-off-by: Brendan Higgins <brendanhiggins@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Logan Gunthorpe <logang@deltatee.com> Reviewed-by: Stephen Boyd <sboyd@kernel.org> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
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3.2 KiB
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63 lines
3.2 KiB
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.. SPDX-License-Identifier: GPL-2.0
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==========================
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Frequently Asked Questions
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==========================
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How is this different from Autotest, kselftest, etc?
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====================================================
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KUnit is a unit testing framework. Autotest, kselftest (and some others) are
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not.
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A `unit test <https://martinfowler.com/bliki/UnitTest.html>`_ is supposed to
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test a single unit of code in isolation, hence the name. A unit test should be
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the finest granularity of testing and as such should allow all possible code
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paths to be tested in the code under test; this is only possible if the code
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under test is very small and does not have any external dependencies outside of
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the test's control like hardware.
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There are no testing frameworks currently available for the kernel that do not
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require installing the kernel on a test machine or in a VM and all require
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tests to be written in userspace and run on the kernel under test; this is true
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for Autotest, kselftest, and some others, disqualifying any of them from being
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considered unit testing frameworks.
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Does KUnit support running on architectures other than UML?
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===========================================================
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Yes, well, mostly.
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For the most part, the KUnit core framework (what you use to write the tests)
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can compile to any architecture; it compiles like just another part of the
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kernel and runs when the kernel boots. However, there is some infrastructure,
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like the KUnit Wrapper (``tools/testing/kunit/kunit.py``) that does not support
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other architectures.
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In short, this means that, yes, you can run KUnit on other architectures, but
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it might require more work than using KUnit on UML.
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For more information, see :ref:`kunit-on-non-uml`.
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What is the difference between a unit test and these other kinds of tests?
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==========================================================================
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Most existing tests for the Linux kernel would be categorized as an integration
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test, or an end-to-end test.
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- A unit test is supposed to test a single unit of code in isolation, hence the
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name. A unit test should be the finest granularity of testing and as such
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should allow all possible code paths to be tested in the code under test; this
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is only possible if the code under test is very small and does not have any
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external dependencies outside of the test's control like hardware.
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- An integration test tests the interaction between a minimal set of components,
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usually just two or three. For example, someone might write an integration
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test to test the interaction between a driver and a piece of hardware, or to
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test the interaction between the userspace libraries the kernel provides and
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the kernel itself; however, one of these tests would probably not test the
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entire kernel along with hardware interactions and interactions with the
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userspace.
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- An end-to-end test usually tests the entire system from the perspective of the
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code under test. For example, someone might write an end-to-end test for the
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kernel by installing a production configuration of the kernel on production
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hardware with a production userspace and then trying to exercise some behavior
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that depends on interactions between the hardware, the kernel, and userspace.
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