## TL;DR
This revision addresses comments from Linus[1] and Randy[2], by moving top level `kunit/` directory to `lib/kunit/` and likewise moves top level Kconfig entry under lib/Kconfig.debug, so the KUnit submenu now shows up under the "Kernel Hacking" menu.
As a consequence of this, I rewrote patch 06/18 (kbuild: enable building KUnit), and now needs to be re-acked/reviewed.
## Background
This patch set proposes KUnit, a lightweight unit testing and mocking framework for the Linux kernel.
Unlike Autotest and kselftest, KUnit is a true unit testing framework; it does not require installing the kernel on a test machine or in a VM (however, KUnit still allows you to run tests on test machines or in VMs if you want[3]) and does not require tests to be written in userspace running on a host kernel. Additionally, KUnit is fast: From invocation to completion KUnit can run several dozen tests in about a second. Currently, the entire KUnit test suite for KUnit runs in under a second from the initial invocation (build time excluded).
KUnit is heavily inspired by JUnit, Python's unittest.mock, and Googletest/Googlemock for C++. KUnit provides facilities for defining unit test cases, grouping related test cases into test suites, providing common infrastructure for running tests, mocking, spying, and much more.
### What's so special about unit testing?
A unit test is supposed to test a single unit of code in isolation, hence the name. There should be no dependencies outside the control of the test; this means no external dependencies, which makes tests orders of magnitudes faster. Likewise, since there are no external dependencies, there are no hoops to jump through to run the tests. Additionally, this makes unit tests deterministic: a failing unit test always indicates a problem. Finally, because unit tests necessarily have finer granularity, they are able to test all code paths easily solving the classic problem of difficulty in exercising error handling code.
### Is KUnit trying to replace other testing frameworks for the kernel?
No. Most existing tests for the Linux kernel are end-to-end tests, which have their place. A well tested system has lots of unit tests, a reasonable number of integration tests, and some end-to-end tests. KUnit is just trying to address the unit test space which is currently not being addressed.
### More information on KUnit
There is a bunch of documentation near the end of this patch set that describes how to use KUnit and best practices for writing unit tests. For convenience I am hosting the compiled docs here[4].
Additionally for convenience, I have applied these patches to a branch[5]. The repo may be cloned with: git clone https://kunit.googlesource.com/linux This patchset is on the kunit/initial/v5.3/v16 branch.
[1] https://www.lkml.org/lkml/2019/9/20/696 [2] https://www.lkml.org/lkml/2019/9/20/738 [3] https://google.github.io/kunit-docs/third_party/kernel/docs/usage.html#kunit... [4] https://google.github.io/kunit-docs/third_party/kernel/docs/ [5] https://kunit.googlesource.com/linux/+/kunit/initial/v5.3/v16
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Avinash Kondareddy (1): kunit: test: add tests for KUnit managed resources
Brendan Higgins (16): kunit: test: add KUnit test runner core kunit: test: add test resource management API kunit: test: add string_stream a std::stream like string builder kunit: test: add assertion printing library kunit: test: add the concept of expectations lib: enable building KUnit in lib/ kunit: test: add initial tests objtool: add kunit_try_catch_throw to the noreturn list kunit: test: add support for test abort kunit: test: add tests for kunit test abort kunit: test: add the concept of assertions kunit: defconfig: add defconfigs for building KUnit tests Documentation: kunit: add documentation for KUnit MAINTAINERS: add entry for KUnit the unit testing framework MAINTAINERS: add proc sysctl KUnit test to PROC SYSCTL section kunit: fix failure to build without printk
Felix Guo (1): kunit: tool: add Python wrappers for running KUnit tests
Iurii Zaikin (1): kernel/sysctl-test: Add null pointer test for sysctl.c:proc_dointvec()
Documentation/dev-tools/index.rst | 1 + Documentation/dev-tools/kunit/api/index.rst | 16 + Documentation/dev-tools/kunit/api/test.rst | 11 + Documentation/dev-tools/kunit/faq.rst | 62 + Documentation/dev-tools/kunit/index.rst | 79 + Documentation/dev-tools/kunit/start.rst | 180 ++ Documentation/dev-tools/kunit/usage.rst | 576 +++++++ MAINTAINERS | 13 + arch/um/configs/kunit_defconfig | 3 + include/kunit/assert.h | 356 ++++ include/kunit/string-stream.h | 51 + include/kunit/test.h | 1490 +++++++++++++++++ include/kunit/try-catch.h | 75 + kernel/Makefile | 2 + kernel/sysctl-test.c | 392 +++++ lib/Kconfig.debug | 13 + lib/Makefile | 2 + lib/kunit/Kconfig | 38 + lib/kunit/Makefile | 9 + lib/kunit/assert.c | 141 ++ lib/kunit/example-test.c | 88 + lib/kunit/string-stream-test.c | 52 + lib/kunit/string-stream.c | 217 +++ lib/kunit/test-test.c | 331 ++++ lib/kunit/test.c | 478 ++++++ lib/kunit/try-catch.c | 118 ++ tools/objtool/check.c | 1 + tools/testing/kunit/.gitignore | 3 + tools/testing/kunit/configs/all_tests.config | 3 + tools/testing/kunit/kunit.py | 136 ++ tools/testing/kunit/kunit_config.py | 66 + tools/testing/kunit/kunit_kernel.py | 149 ++ tools/testing/kunit/kunit_parser.py | 310 ++++ tools/testing/kunit/kunit_tool_test.py | 206 +++ .../test_is_test_passed-all_passed.log | 32 + .../test_data/test_is_test_passed-crash.log | 69 + .../test_data/test_is_test_passed-failure.log | 36 + .../test_is_test_passed-no_tests_run.log | 75 + .../test_output_isolated_correctly.log | 106 ++ .../test_data/test_read_from_file.kconfig | 17 + 40 files changed, 6003 insertions(+) create mode 100644 Documentation/dev-tools/kunit/api/index.rst create mode 100644 Documentation/dev-tools/kunit/api/test.rst create mode 100644 Documentation/dev-tools/kunit/faq.rst create mode 100644 Documentation/dev-tools/kunit/index.rst create mode 100644 Documentation/dev-tools/kunit/start.rst create mode 100644 Documentation/dev-tools/kunit/usage.rst create mode 100644 arch/um/configs/kunit_defconfig create mode 100644 include/kunit/assert.h create mode 100644 include/kunit/string-stream.h create mode 100644 include/kunit/test.h create mode 100644 include/kunit/try-catch.h create mode 100644 kernel/sysctl-test.c create mode 100644 lib/kunit/Kconfig create mode 100644 lib/kunit/Makefile create mode 100644 lib/kunit/assert.c create mode 100644 lib/kunit/example-test.c create mode 100644 lib/kunit/string-stream-test.c create mode 100644 lib/kunit/string-stream.c create mode 100644 lib/kunit/test-test.c create mode 100644 lib/kunit/test.c create mode 100644 lib/kunit/try-catch.c create mode 100644 tools/testing/kunit/.gitignore create mode 100644 tools/testing/kunit/configs/all_tests.config create mode 100755 tools/testing/kunit/kunit.py create mode 100644 tools/testing/kunit/kunit_config.py create mode 100644 tools/testing/kunit/kunit_kernel.py create mode 100644 tools/testing/kunit/kunit_parser.py create mode 100755 tools/testing/kunit/kunit_tool_test.py create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-all_passed.log create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-crash.log create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-failure.log create mode 100644 tools/testing/kunit/test_data/test_is_test_passed-no_tests_run.log create mode 100644 tools/testing/kunit/test_data/test_output_isolated_correctly.log create mode 100644 tools/testing/kunit/test_data/test_read_from_file.kconfig