  Asynchronous waits are one of the most prevalent root causes of flaky tests
and a major time-influential factor of web application testing. To investigate
the characteristics of asynchronous wait flaky tests and their fixes in web
testing, we build a dataset of 49 reproducible flaky tests, from 26 open-source
projects, caused by asynchronous waits, along with their corresponding
developer-written fixes. Our study of these flaky tests reveals that in
approximately 63% of them (31 out of 49), developers addressed Asynchronous
Wait flaky tests by adapting the wait time, even for cases where the root
causes lie elsewhere. Based on this finding, we propose TRaf, an automated
time-based repair method for asynchronous wait flaky tests in web applications.
TRaf tackles the flakiness issues by suggesting a proper waiting time for each
asynchronous call in a web application, using code similarity and past change
history. The core insight is that as developers often make similar mistakes
more than once, hints for the efficient wait time exist in the current or past
codebase. Our analysis shows that TRaf can suggest a shorter wait time to
resolve the test flakiness compared to developer-written fixes, reducing the
test execution time by 11.1%. With additional dynamic tuning of the new wait
time, TRaf further reduces the execution time by 20.2%.
