Skip to content

fix(wda): an element is not visible only when a lookup finds it absent - #184

Merged
omnarayan merged 4 commits into
devicelab-dev:mainfrom
vyrahealth:upstream-pr/wda-notvisible-needs-a-miss
Oct 1, 2026
Merged

omnarayan merged 4 commits into
devicelab-dev:mainfrom
vyrahealth:upstream-pr/wda-notvisible-needs-a-miss

Conversation

@bulatgaleev

@bulatgaleev bulatgaleev commented Sep 29, 2026 •

Copy link
Copy Markdown
Contributor

Summary

Maestro's notVisible waits for a lookup that ends in ElementNotFound (Orchestra.kt); any other lookup error fails the step. assertNotVisible and extendedWaitUntil: notVisible treated any failed lookup (err != nil || info == nil) as the element being gone, so a page source that could not be read, from a WDA error or a dropped connection, passed the assertion without the screen ever being looked at. The when/while and assertCondition notVisible checks go through assertNotVisible and had the same hole. Now only a lookup that read the screen and found nothing counts as gone.

Type of Change

  • Bug fix (non-breaking change that fixes an issue)
  • New feature (non-breaking change that adds functionality)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Documentation update
  • Refactoring (no functional changes)

Changes Made

  • The page-source lookups return a not-found error when they read the screen and nothing matches, an anchor that is not there included. Only that counts as gone.
  • Any other error is tried again until the timeout, and then the step fails with that error.
  • TestAssertNotVisibleWithTimeout served an error for every request and expected a pass; it now serves an empty screen.
  • pkg/driver/wda/notvisible_test.go, and a CHANGELOG.md entry.

Related Issues

No existing issue found.

Testing

  • go test ./pkg/driver/wda/
  • Added tests for new functionality
  • Running on a physical iPhone (iOS 27, WebDriverAgent reached through a forwarded port) in our nightly 46-flow suite, as part of our fork's build
  • go vet ./... and make fmt-check pass (run on the top of the stack, fix(wda): checked selectors work on iOS #185, which contains all five changes)
  • make test as a whole: not run, because its device tests drive whatever device is attached to the machine
  • make lint: the Makefile has no lint target, and the linters make check runs (staticcheck, revive, errcheck, nilaway, gosec) are not installed here

Checklist

  • Code follows project style guidelines
  • Self-reviewed the code
  • Added/updated documentation as needed (no documentation change needed)
  • No breaking changes (or documented if breaking)
  • CHANGELOG.md updated (for notable changes)

Additional Notes

A notVisible check that used to pass because the screen could not be read now retries, and fails with the lookup's error if the screen still cannot be read at the timeout.

Stack 4 of 5: #181 → #182 → #183 → #184 → #185. Merge in that order. This branch is built on #181, #182 and #183, so it also contains their commits. This PR's own change is the top commit, 8ccc104. Once the PRs below it merge, the rest of the diff disappears, and nothing conflicts. All five sit on main at fe3dd53 (the 1.1.28 release).

The WDA driver reads an element's name, rect, text and displayed in
parallel, and a tap looks an element up four ways at once. The client used
Go's default transport, which keeps two idle connections per host, so every
such burst closed two connections and opened two new ones.

On a real iPhone reached through a forward (SSH, then iproxy over USB) a
new connection costs about 300 ms, and new ones opened together fail at
once with EOF. In one 44-flow run, 297 of 996 element bursts lost exactly
two reads (the two new connections), 2 lost one, and none lost a read on a
kept connection: 976 EOFs, each sent again by the dropped-connection
retry. WebDriverAgent does not close an idle keep-alive connection
(FBHTTPServer exempts them from its reaper), so a stale reuse was not the
cause.

The client now keeps up to eight idle connections per host. In the new
tests, 50 bursts of four reads open 4 connections instead of 102, and
through a server that drops every new connection past the first four, no
read fails (the old client lost 23 reads there, after 196 dropped
connections).
Maestro runs a retry's commands once and then up to maxRetries more times:
`(maxRetries?.toIntOrNull() ?: 1).coerceAtMost(3)`, then
`while (attempt <= maxRetries)` from 0 (Orchestra.kt:934-955, with
MAX_RETRIES_ALLOWED at 1844 and the "1" default at YamlFluentCommand.kt:614).
So `maxRetries: 1` is two attempts, the default is two, and no retry runs
more than four times. The value is evaluated first, so ${...} works
(Commands.kt:986), and anything that is not an integer counts as 1.

The runner ran exactly maxRetries attempts, three when unset, with no cap,
so a flow written with `maxRetries: 1` never retried at all. It also failed
the step when maxRetries was not an integer. The inline and the file form
of retry now count as Maestro does. A negative maxRetries runs no attempt
and passes, since Maestro's loop never starts. A value that is not an
integer is logged and read as 1.
Maestro stops the app before launching it unless the flow says
`stopApp: false`. The WDA driver never read stopApp: with a session open and
no launch arguments it called WDA's launch on the running app, which only
activates it. A relaunch then left the app on the screen it was already on,
so a flow checking what survives a restart (a chat's history, or a changed
subscription state being read back on launch) was not restarting anything.

It now terminates first unless stopApp is false. Launch arguments still
force the stop, since they only apply on a real launch. A launchApp that
creates the session is unchanged: creating it launches the app fresh.
Maestro's notVisible waits for a lookup that ends in ElementNotFound
(Orchestra.kt:1066-1082); any other error from the lookup fails the step.

assertNotVisible and extendedWaitUntil notVisible treated any failed lookup
(err != nil || info == nil) as the element being gone. A page source that
could not be read, from a WDA error or a dropped connection, passed the
assertion without the screen ever being looked at. The when/while and
assertCondition notVisible checks go through assertNotVisible, so they had
the same hole.

The page-source lookups now return a not-found error when they read the
screen and nothing matches (an anchor that is not there included). Only that
counts as gone. Any other error is tried again until the timeout, and the
step then fails with that error ("Could not check that ... is not visible").
TestAssertNotVisibleWithTimeout served an error for every request and
expected a pass; it now serves an empty screen.
@bulatgaleev
bulatgaleev force-pushed the upstream-pr/wda-notvisible-needs-a-miss branch from 3486b7e to 8ccc104 Compare September 30, 2026 14:49
@omnarayan

Copy link
Copy Markdown
Contributor

Thank you @bulatgaleev. Good catch: a page source that could not be read should not pass assertNotVisible, and this matches Maestro's notVisible (only ElementNotFound counts as gone).

It can make WDA flows that were passing on a failed read fail now. That's the correct result, and we'll mention it in the release notes. Merging into main now; it ships in 1.1.29.

@omnarayan
omnarayan merged commit 509d11f into devicelab-dev:main Oct 1, 2026
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants