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Building and Running Tests

Building tests

Fundamentally, a test has two main phases:
  • run_*() - This is is the main part that performs all testing and is invoked by the control files, once or repeatedly.
  • setup() - This function, present in the test case’s main .py file is supposed to prepare the test for running. This includes building any binaries, initializing data, etc.

During building using emerge, autotest will call a setup() function of all test cases/deps involved. This is supposed to prepare everything. Typically, this will invoke make on a Makefile present in the test’s src/ directory, but can involve any other transformation of sources (also be empty if there’s nothing to build).
Note, however, that setup() is implicitly called many times as test initialization even during run_*() step, so it should be a noop on reentry that merely verifies everything is in order.

Unlike run_*() functions, setup() gets called both during the prepare phase which happens on the host and target alike. This creates a problem with code that is being depended on or directly executed during setup(). Python modules that are imported in any pathway leading to setup() are needed both in the host chroot and on the target board to properly support the test. Any binaries would need to be compiled using the host compiler and either ensured that they will be skipped on the target (incremental setup() runs) or cross-compiled again and dynamically chosen while running on target.

More importantly, in Chromium OS scenario, doing any write operations inside the setup() function will lead to access denied failures, because tests are being run from the intermediate read-only location.

Given the above, building is as easy as emerge-ing the autotest ebuild that contains our test.

$ emerge-${board} ${test_ebuild}

Currently, tests are organized within these notable ebuilds: (see FAQ full list)
chromeos-base/autotest-tests - The main ebuild handling most of autotest.git repository and its client and server tests.
chromeos-base/autotest-tests-* - Various ebuilds that build other parts of autotest.git
chromeos-base/chromeos-chrome - chrome tests; the tests that are part of chrome

Building tests selectively

Test cases built by ebuilds generally come in large bundles. Sometimes, only a subset, or generally a different set of the tests provided by a given ebuild is desired. That is achieved using a USE_EXPANDed flag called TESTS.

All USE flags (and therefore tests) have a default state, either enabled (+) or disabled (-), specified directly in the ebuild, that can be manually overridden from the commandline. There are two ways to do that.
  • Non-Incremental - Simply override the default selection by an entirely new selection, ignoring the defaults. This is useful if you develop a single test and don’t want to waste time building the others.
$ TESTS="test1 test2" emerge-${board} ${ebuild}
  • Incremental - All USE_EXPAND flags are also accessible as USE flags, with the appropriate prefix, and can be used incrementally to selectively enable/disable tests in addition to the defaults. This can be useful if you aim to enable a test that is disabled by default and want to test locally.
$ USE="test_to_be_enabled -test_to_be_disabled" emerge-${board} ${ebuild}

For operations across all tests, following incremental USE wildcard is supported by portage: "tests_*" to select all tests at once (or - to de-select).
NOTE: Both Incremental and Non-Incremental methods can be set/overriden by (in this order): the ebuild (default values), make.profile, make.conf, /etc/portage, commandline (see above). That means that any settings provided on the emerge commandline override everything else.

Running tests

NOTE: In order to run tests on your device, it needs to have a test-enabled image.

When running tests, fundamentally, you want to either:
  • Run sets of tests manually - Use case: Developing test cases
Take your local test sources, modify them, and then attempt to run them on a target machine using autotest. You are generally responsible for making sure that the machine is imaged to a test image, and the image contains all the dependencies needed to support your tests.
  • Verify a given image - Use case: Developing the projects subject to testing
Take an image, re-image the target device and run a test suite on it. This requires either use of build-time autotest artifacts or their reproduction by not modifying or resyncing your sources after an image has been built.

Running tests on a machine - test_that

The frontend for running tests is a script called test_that. It provides an interface for running the autoserv process which deploys and executes tests on remote machines.

Most basically, test_that takes several flags for specifying the remote machine IP address and a list of control files. Control files can be specified either by their NAME field, or by a NAME- or path- matching regular expression. For example:
$ test_that dummy_Pass

This script will use autotest_quickmerge to copy over any python-only test changes from your source tree to the board sysroot, if it detects that your source tree is newer. This allows you to iterate rapidly on python only changes without needing to emerge your changes. However, non-python changes still require a normal emerge.

Running tests in a VM - cros_run_vm_tests

WARNING: After crbug/710629, 'betty' is the only board regularly run through pre-CQ and CQ VMTest and so is the most likely to work at ToT. 'betty' is based on 'amd64-generic', though, so 'amd64-generic' is likely to also work for most (non-ARC) tests.

VM tests are conveniently wrapped into a script cros_run_vm_tests that sets up the VM using a given image and then calls
test_that. This is run by builders to test using the Smoke suite.
If you want to run your tests on the VM (see here for basic instructions for setting up KVM with cros images) be aware of the following:
  • cros_run_vm_test starts up a VM and runs test_that using the port specified (defaults to 9222).  As an example:
$ ./bin/cros_run_vm_test --test_case=suite_Smoke ---image_path=<my_image_to_start or don't set to use most recent build> --board=betty # or 'amd64-generic'
  • The emulator command line redirects localhost port 922 to the emulated machine's port 22 to allow you to ssh into the emulator. For Chromium OS to actually listen on this port you must append the --test_image parameter when you run the ./ script, or perhaps run the script instead.
  • You can then run tests on the correct ssh port with something like
$ ./test_that --board=x86-generic localhost:922 platform_BootPerf
  • To set the sudo password run set_shared_user_password. Then within the emulator you can press Ctrl-Alt-T to get a terminal, and sudo using this password. This will also allow you to ssh into the unit with, e.g.
$ ssh -p 922 root@localhost

Interpreting test results 

Running autotest will result in a lot of information going by which is probably not too informative if you have not used autotest before.  At the end of the test_that run, you will see a summary of pass/failure status, along with performance results:

22:44:30 INFO | Using installation dir /home/autotest
22:44:30 ERROR| Could not install autotest from repos
22:44:32 INFO | Installation of autotest completed
22:44:32 INFO | GOOD  ----  Autotest.install timestamp=1263509072 localtime=Jan 14 22:44:32
22:44:33 INFO | Executing /home/autotest/bin/autotest /home/autotest/control phase 0
22:44:36 INFO | START  ---- ----  timestamp=1263509075 localtime=Jan 14 14:44:35
22:44:36 INFO |  START   sleeptest sleeptest timestamp=1263509076 localtime=Jan 14 14:44:36
22:44:36 INFO | Bundling /usr/local/autotest/client/tests/sleeptest into test-sleeptest.tar.bz2
22:44:40 INFO |   GOOD  sleeptest  sleeptest  timestamp=1263509079  localtime=Jan 14 14:44:39 completed successfully
22:44:40 INFO |   END GOOD  sleeptest sleeptest  timestamp=1263509079  localtime=Jan 14 14:44:39
22:44:42 INFO | END GOOD ---- ---- timestamp=1263509082 localtime=Jan 14 14:44:42
22:44:44 INFO | Client complete
22:44:45 INFO | Finished processing control file

A directory full of the latest results will also be left at /tmp/test_that_latest

Running tests automatically, Suites

Suites provide a mechanism to group tests together in test groups. They also serve as hooks for automated runs of tests verifying various builds. Most importantly, that is the BVT (board verification tests) and Smoke (a subset of BVT that can run in a VM

Please refer to the suites documentation


Fairly asked questions, because yes, some of this may be confusing!

Q1: What autotest ebuilds are out there?

Note that the list of ebuilds may differ per board, as each board has potentially different list of overlays. To find all autotest ebuilds for board foo, you can run:
$ board=foo
$ for dir in $(portageq-${board} envvar PORTDIR_OVERLAY); do
    find . -name '*.ebuild' | xargs grep "inherit.*autotest" | grep "9999" |cut -f1 -d: | \
    sed -e 's/.*\/\([^/]*\)\/\([^/]*\)\/.*\.ebuild/\1\/\2/'

Q2: I see a test of the name ‘greattests_TestsEverything’ in build output/logs/whatever! How do I find which ebuild builds it?

All ebuilds have lists of tests exported as USE_EXPANDed lists called TESTS. An expanded use can be searched for in the same way as other use flags, but with the appropriate prefix, in this case, you would search for ‘tests_greattests_TestsEverything’:
$ use_search=tests_greattests_TestsEverything
$ equery-$board hasuse $use_search
* Searching for USE flag tests_greattests_TestsEverything …
[I-O] [  ] some_ebuild_package_name:0

This will however only work on ebuilds which are already installed, ie. their potentially outdated versions.
Alternately, you can run a pretended emerge (emerge -p) of all autotest ebuilds and scan the output.
$ emerge -p ${all_ebuilds_from_Q1} |grep -C 10 “${use_search}”

Q3: I have an ebuild ‘foo’, where are its sources?

Generally speaking, one has to look at the ebuild source to figure that question out (and it shouldn’t be hard). However, all present autotest ebuilds (at the time of this writing) are also ‘cros-workon’, and for those, this should always work:
$ ebuild_search=foo
$ ebuild $(equery-$board which $ebuild_search) info

Q4: I have an ebuild, what tests does it build?

You can run a pretended emerge on the ebuild and observe the ‘TESTS=’ statement:
$ ebuild_name=foo
$ emerge-$board -pv ${ebuild_name}
These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild   R   ] foo-foo_version to /build/$board/ USE="autox hardened tpmtools xset -buildcheck -opengles" TESTS="enabled_test1 enabled_test2 … enabled_testN -disabled_test1 ...disabled_testN" 0 kB [1]

Alternately, you can use equery, which will list tests with the USE_EXPAND prefix:
$ equery-$board uses ${ebuild_name}
[ Legend : U - final flag setting for installation]
[        : I - package is installed with flag     ]
[ Colors : set, unset                             ]
* Found these USE flags for chromeos-base/autotest-tests-9999:
+ + autotest                                    : <unknown>
+ + autotest                                    : <unknown>
+ + autox                                       : <unknown>
+ + buildcheck                                  : <unknown>
+ + hardened                                    : activate default security enhancements for toolchain (gcc, glibc, binutils)
- - opengles                                    : <unknown>
+ + tests_enabled_test                     : <unknown>
- - tests_disabled_test                      : <unknown>

Q5: I’m working on some test sources, how do I know which ebuilds to cros_workon start in order to properly propagate?

You should ‘workon’ and always cros_workon start all ebuilds that have files that you touched.
If you’re interested in a particular file/directory, that is installed in /build/$board/usr/local/autotest/ and would like know which package has provided that file, you can use equery:
$ equery-$board belongs /build/${board}/usr/local/autotest/client/site_tests/foo_bar/
* Searching for <filename> …
chromeos-base/autotest-tests-9999 (<filename>)

DON’T forget to do equery-$board. Just equery will also work, only never return anything useful.

As a rule of thumb, if you work on anything from the core autotest framework or shared libraries (anything besides {server,client}/{test,site_tests,deps,profilers,config}), it belongs to chromeos-base/autotest. Individual test case will each belong to a particular ebuild, see Q2.

It is important to cros_workon start every ebuild involved.

Q6: I created a test, added it into ebuild, emerged it, and I’m getting access denied failures. What did I do wrong?

Your test’s setup() function (which runs on the host before being uploaded) is probably trying to write into the read-only intermediate location.

Q7: Missing pyauto_dep

You're seeing something like:
Missing pyauto_dep. Unhandled PackageInstallError: Installation of pyauto_dep(type:dep) failed : dep-pyauto_dep.tar.bz2 could not be fetched from any of the repos ['autoserv://']

You're running the now-deprecated without the --use_emerged flag. Use test_that instead. OR, you are using test_that but have never emerged autotest-chrome, and thus the telemetry dep is missing. See here.