The Gradle plugin discards adb's exit code and standard error

[DanielJette]

Found while fixing #245, and only partly addressed there.

runProcess reads the process's standard output and nothing else (Plugins/Gradle/src/main/kotlin/dev/testify/internal/ClientUtilities.kt):

val process = Runtime.getRuntime().exec(command)
val result = streamData.handleInputStream(process.inputStream)
process.waitFor()
return result

Two signals are thrown away:

1. Standard error. Anything adb or the device-side command writes there is invisible to the caller.
2. The exit code. waitFor()'s return value is discarded, so a command that failed outright looks the same as one that succeeded.

The concrete case this produced: with the application under test not installed, screenshotTest on a com.android.test module printed INSTRUMENTATION_STATUS: Error=Unable to find instrumentation target package, ran zero tests, and reported BUILD SUCCESSFUL. #333 fixes that one path by giving runProcess an opt-in redirectErrorStream that the am instrument call uses.

Every other call site still has the gap. screenshotPull, screenshotClear, reportPull and the device-setup tasks all go through Adb.execute(), so an adb failure in any of them is silent — a pull that copies nothing looks like a pull with nothing to copy.

Suggested fix: check the exit code in runProcess and surface a non-zero one. That is the better signal than string-matching stderr, but it needs checking per call site first: some commands are expected to fail benignly, and listFiles already appends 2>/dev/null precisely because a missing directory is normal. A blanket throw would break those.

Worth doing as its own change, with the call sites audited, rather than widening #333.