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fix(executor): read when: true: and assertTrue values as Maestro does - #198

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bulatgaleev wants to merge 6 commits into
devicelab-dev:mainfrom
vyrahealth:upstream-pr/b2-condition-truthiness
Open

bulatgaleev wants to merge 6 commits into
devicelab-dev:mainfrom
vyrahealth:upstream-pr/b2-condition-truthiness

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@bulatgaleev

@bulatgaleev bulatgaleev commented Oct 2, 2026 •

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Summary

Maestro evaluates each ${...} of a condition's value and then reads the text as false only when it is blank, false in any case, undefined, null or a number equal to zero, so abc or YES is true (evaluateCondition in Orchestra.kt, after Condition.evaluateScripts in Condition.kt, at cli-2.10.0). An undeclared name evaluates to undefined (GraalJsEngine.kt). maestro-runner took a string as true only when it was exactly true, so assertTrue: ${name} failed for any other value. A when: or while: value fared worse: ExpandCondition replaced the ${...} with its value, and EvalCondition then ran that value as JavaScript again. abc became a ReferenceError and YES an undefined name, both false, and an unset variable expanded to an empty string, which CheckCondition took as no condition at all, so when: true: ${UNSET} ran the branch Maestro skips. A string result now goes through Maestro's rule, and a condition that is one ${...} is evaluated once.

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

  • EvalCondition reads a string result with maestroTruthy: false when it is blank, false in any case, undefined, null or a number equal to zero, true otherwise.
  • A condition that is one ${...} (isWholeExpression) is no longer expanded by ExpandCondition, so EvalCondition evaluates the expression once and reads its value. A condition with text around its ${...} still expands first and runs as JavaScript, as before.
  • Every undeclared name in a condition is defined as undefined. Before, only the ALL_CAPS ones were, so this keeps ${maybe || 'x'} working now that the expression is evaluated there.
  • pkg/executor/truthiness_test.go, and one case of TestScriptEngine_EvalCondition that expected 'yes' to be false and now expects it to be true. Without the change, assertTrue: ${name} fails for abc, and when: true: ${UNSET_FLAG} runs its branch while when: true: ${NAME} does not.
  • A CHANGELOG.md entry.

Related Issues

No existing issue found. #60 and #176 (both closed) were also about when: true:: in one the condition was dropped, in the other it was expanded once and reused. Neither is about how its value is read.

Testing

  • go test ./pkg/executor/
  • Added tests for new functionality
  • Part of our fork's build, which runs a 47-flow suite every night on a physical iPhone (iOS 27, WebDriverAgent reached through a forwarded port). The tests above are the evidence for this change, not that suite
  • go test -race for pkg/executor, pkg/driver/wda, pkg/jsengine, pkg/flow and pkg/driver/uiautomator2 passes at the top of the stack; go vet ./..., gofmt -l and golangci-lint v2.13.2 (the version CI pins) report nothing on every branch of the stack
  • 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 other 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

Strings that Maestro reads as true are now true here: assertTrue: ${'no'} passes, and when: true: ${NAME} runs its branch for any non-blank NAME that is not false, undefined, null or zero. A when: or while: on a variable that is not set now skips its branch, where it used to run it.

Stack 6 of 7: #200 → #194 → #195 → #196 → #197 → #198 → #199. Merge in that order. This branch is built on #200, #194, #195, #196 and #197, so it also contains their commits. This PR's own change is the top commit, e8856cf. Once the PRs below it merge, the rest of the diff disappears, and nothing conflicts. All seven sit on main at d3f738f (the merge of #185).

@codecov

codecov Bot commented Oct 2, 2026

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Codecov Report

❌ Patch coverage is 98.03922% with 1 line in your changes missing coverage. Please review.

Files with missing lines Patch % Lines
pkg/executor/scripting.go 96.87% 0 Missing and 1 partial ⚠️

📢 Thoughts on this report? Let us know!

…lls any more

30257df (Android device queries match the whole text and id) took out the last
caller of this helper in the uiautomator2 driver. The unused linter has flagged
it since, so Lint has failed on every push to main, and Build, which needs
Lint, has been skipped each time. The same helper in the appium and devicelab
drivers is untouched.
Maestro runs a runScript file as plain JavaScript. It reads the file and
evaluates ${...} only in the step's env, when: condition and label; the
script text goes to the engine as it is (YamlFluentCommand.kt:409-424,
Commands.kt:1029-1035, Orchestra.kt:723-737).

The runner expanded ${...} and $VAR across the whole file before running
it. A template literal that used the script's own variables was replaced
ahead of the script, against variables that did not exist yet:
`/v1/x?email=${encodeURIComponent(who)}&state=${state}` came out as
`/v1/x?email=undefined&state=`.

A script file now runs as written. Inline script text, which Maestro has no
equivalent of, keeps the expansion.
Maestro gives a sub-flow its own env scope: enterEnvScope saves the env and
leaveEnvScope puts that copy back, so a key the sub-flow added is gone when
it returns (GraalJsEngine.kt:223-238, around runSubFlow at
Orchestra.kt:1159-1197, which repeat, retry and runFlow all go through).

The runner's withEnvVars restored each key to the value it had before, and
a key that had none was set to "" rather than removed. After a runFlow,
retry or sub-flow with `env: {KEY: ...}`, KEY stayed defined: typeof KEY was
"string", `$KEY` expanded to nothing, and runShell saw KEY="" in its
environment.

withEnvVars now uses applyScopedEnv, which runScript's env already used:
a key is restored when it existed and removed when it did not.
Maestro builds its script http client with 5-minute read, write and call
timeouts (GraalJsEngine.kt:28-34), and the CLI passes no client of its own
(Orchestra.kt:138 and 161), so every call gets them.

The runner's http.* gave a call 30 s unless the call set `timeout`, so a
script that calls a slow endpoint (seeding test data, waiting on a
server-side job) failed with "HTTP request failed" where Maestro waits. A
local server that answered after 32 s failed the call at 30 s.

A call without a timeout option now gets 5 minutes. The option still wins.
On a physical iPhone reached through usbmux and an SSH tunnel, WDA began
dropping connections 90 minutes into a run: about one request in fourteen
came back as EOF within about 10 ms, nearly all of them element reads sent
in parallel (displayed, text, rect, name). Most were harmless, but a dropped
text read made a copyTextFrom come back empty and failed the flow. A fresh
WDA dropped none, in seven other runs.

net/http does not help here. It sends a request again by itself only when it
is a GET on a connection that had been used before (shouldRetryRequest), so
a fresh connection that is hung up on, and any POST, come back as errors.

A GET, or a POST that only finds elements, whose connection dies before any
response (EOF, reset, broken pipe) is now sent once more, with a warning in
the log. An action (a tap, typing, a swipe, launching an app) is never
repeated: it may have reached WDA before the connection went. One more try,
not a loop.

The changelog entry for keeping idle connections said those requests are sent
again. That is only true with this change, so the entry is reworded.
Maestro evaluates each ${...} of the value and then reads the text as false
only when it is blank, "false" in any case, "undefined", "null" or a number
equal to zero, so "abc" or "YES" is true (Orchestra.kt:1030-1052, after
Condition.evaluateScripts at Condition.kt:15-21). An undeclared name
evaluates to undefined (GraalJsEngine.kt:198-204).

The runner took a string as true only when it was exactly "true", so
`assertTrue: ${name}` failed for any other value. A when: or while: value
fared worse: ExpandCondition replaced the ${...} with its value, and
EvalCondition then ran that value as JavaScript again. "abc" became a
ReferenceError and "YES" an undefined name, both false, and an unset
variable expanded to "", which CheckCondition took as no condition at all,
so `when: true: ${UNSET}` ran the branch Maestro skips.

A string result now goes through Maestro's rule. A condition that is one
${...} is no longer expanded ahead of the check: EvalCondition evaluates the
expression once and reads its value. Every undeclared name in a condition
is undefined, not only the ALL_CAPS ones, so `${maybe || 'x'}` keeps working
now that it is evaluated there. A condition with text around its ${...}
still expands and runs as JavaScript, as before.
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