patch 9.1.1110: Vim tests are slow and flaky
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: #16615
Signed-off-by: Yee Cheng Chin <ychin.git@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/testdir/test_visual.vim b/src/testdir/test_visual.vim
index 03335a4..6c2ef59 100644
--- a/src/testdir/test_visual.vim
+++ b/src/testdir/test_visual.vim
@@ -1559,10 +1559,12 @@
func Test_visual_hl_with_showbreak()
CheckScreendump
+ " Redraw at the end is necessary due to https://github.com/vim/vim/issues/16620
let lines =<< trim END
setlocal showbreak=+
call setline(1, repeat('a', &columns + 10))
normal g$v4lo
+ redraw
END
call writefile(lines, 'XTest_visual_sbr', 'D')