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Problem: Vim tests are slow and flaky at the same time due to reliance
on timeouts which are unreliable.
Solution: improve Vim test performance and reduce flakiness
(Yee Cheng Chin)
A lot of Vim tests currently rely on waiting a specific amount of time
before asserting a condition. This is bad because 1) it is slow, as the
timeout is hardcoded, 2) it's unreliable as a resource-starved runner
may overshoot the timeout. Also, there are a lot of builtin sleep
commands in commonly used utilities like VerifyScreenDump and WaitFor()
which leads to a lot of unnecessary idle time.
Fix these issues by doing the following:
1. Make utilities like VerifyScreenDump and WaitFor use the lowest wait
time possible (1 ms). This essentially turns it into a spin wait. On
fast machines, these will finish very quickly. For existing tests
that had an implicit reliance on the old timeouts (e.g.
VerifyScreenDump had a 50ms wait before), fix the tests to wait that
specific amount explicitly.
2. Fix tests that sleep or wait for long amounts of time to instead
explicitly use a callback mechanism to be notified when a child
terminal job has finished. This allows the test to only take as much
time as possible instead of having to hard code an unreliable
timeout.
With these fixes, tests should 1) completely quickly on fast machines,
and 2) on slow machines they will still run to completion albeit slowly.
Note that previoulsy both were not true. The hardcoded timeouts meant
that on fast machines the tests were mostly idling wasting time, whereas
on slow machines, the timeouts often were not generous enough to allow
them to run to completion.
closes: vim/vim#16615
e70587dbdb
Part of shared.vim and test_crash.vim changes only.
Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>
This directory contains tests for various Vim features.
For testing an indent script see runtime/indent/testdir/README.txt.
If it makes sense, add a new test method to an already existing file. You may
want to separate it from other tests with comment lines.
TO ADD A NEW STYLE TEST:
1) Create a test_<subject>.vim file.
2) Add test_<subject>.res to NEW_TESTS_RES in Make_all.mak in alphabetical
order.
3) Also add an entry "test_<subject>" to NEW_TESTS in Make_all.mak.
4) Use make test_<subject> to run a single test.
At 2), instead of running the test separately, it can be included in
"test_alot". Do this for quick tests without side effects. The test runs a
bit faster, because Vim doesn't have to be started, one Vim instance runs many
tests.
At 4), to run a test in GUI, add "GUI_FLAG=-g" to the make command.
What you can use (see test_assert.vim for an example):
- Call assert_equal(), assert_true(), assert_false(), etc.
- Use assert_fails() to check for expected errors.
- Use try/catch to avoid an exception aborts the test.
- Use test_alloc_fail() to have memory allocation fail. This makes it possible
to check memory allocation failures are handled gracefully. You need to
change the source code to add an ID to the allocation. Add a new one to
alloc_id_T, before aid_last.
- Use test_override() to make Vim behave differently, e.g. if char_avail()
must return FALSE for a while. E.g. to trigger the CursorMovedI autocommand
event. See test_cursor_func.vim for an example.
- If the bug that is being tested isn't fixed yet, you can throw an exception
with "Skipped" so that it's clear this still needs work. E.g.: throw
"Skipped: Bug with <c-e> and popupmenu not fixed yet"
- The following environment variables are recognized and can be set to
influence the behavior of the test suite (see runtest.vim for details)
- $TEST_MAY_FAIL=Test_channel_one - ignore those failing tests
- $TEST_FILTER=Test_channel - only run test that match this pattern
- $TEST_SKIP_PAT=Test_channel - skip tests that match this pattern
- $TEST_NO_RETRY=yes - do not try to re-run failing tests
You can also set them in Vim:
:let $TEST_MAY_FAIL = 'Test_channel_one'
:let $TEST_FILTER = '_set_mode'
:let $TEST_SKIP_PAT = 'Test_loop_forever'
:let $TEST_NO_RETRY = 'yes'
Use an empty string to revert, e.g.:
:let $TEST_FILTER = ''
- See the start of runtest.vim for more help.
TO ADD A SCREEN DUMP TEST:
Mostly the same as writing a new style test. Additionally, see help on
"terminal-dumptest". Put the reference dump in "dumps/Test_func_name.dump".
OLD STYLE TESTS:
There are a few tests that are used when Vim was built without the +eval
feature. These cannot use the "assert" functions, therefore they consist of a
.in file that contains Normal mode commands between STARTTEST and ENDTEST.
They modify the file and the result gets written in the test.out file. This
is then compared with the .ok file. If they are equal the test passed. If
they differ the test failed.
RUNNING THE TESTS:
To run a single test from the src directory:
$ make test_<name>
The below commands should be run from the src/testdir directory.
To run a single test:
$ make test_<name>.res
The file 'messages' contains the messages generated by the test script. If a
test fails, then the test.log file contains the error messages. If all the
tests are successful, then this file will be an empty file.
- To run a single test function from a test script:
$ ../vim -u NONE -S runtest.vim <test_file>.vim <function_name>
- To execute only specific test functions, add a second argument:
$ ../vim -u NONE -S runtest.vim test_channel.vim open_delay
- To run all the tests:
$ make
- To run the test on MS-Windows using the MSVC nmake:
> nmake -f Make_dos.mak
- To run the tests with GUI Vim:
$ make GUI_FLAG=-g
or
$ make VIMPROG=../gvim
- To cleanup the temporary files after running the tests:
$ make clean