`ConversionViewModelProbeFailureTest.an OutOfMemoryError is not swallowed`
deliberately lets a real error escape `viewModelScope.launch`, which has no
exception handler by design -- the ViewModel's KDoc says an OOM raised in the
probe should reach the thread's handler and take the process down.
On the JVM something else takes it. kotlinx-coroutines-test installs a
process-wide collector for uncaught coroutine errors, keeps whatever it catches,
and hands the backlog to the next `runTest` that starts, which throws
UncaughtExceptionsBeforeTest. Every Compose test is a `runTest`: that is how
`createComposeRule` runs a composition. So the error lands on an unrelated test
in an unrelated file, and the message names neither the test that caused it nor
the error's origin.
Nothing has hit it yet only because the sole Compose test in the repo happens to
run before the ViewModel one. R38 adds six more Compose classes in exactly the
two packages that surround it, and the first two of them made the suite fail in
two different files on two consecutive runs of identical, green code -- the
throw is on a real Dispatchers.IO thread, delivered after the state assertion
that ends the test responsible, so which class catches it is a race.
Drain it where a Compose rule is built. A @Before cannot: the rule's `runTest`
wraps the statement that calls it, so it has already thrown. @BeforeClass cannot
either, because Robolectric runs it outside the sandbox classloader, where the
collector is a different object. Constructing the rule is early enough, since
JUnit builds a fresh test-class instance -- and every @get:Rule field on it --
before evaluating any rule.
This is containment, not the cure. The cure is a seam: give the probe hop an
injectable dispatcher the way the constructor already does for
cleanupDispatcher, so the error has somewhere to land. That is a production
change and deserves its own commit.
kotlinx-coroutines-test was already on the unit-test classpath through
compose-ui-test-junit4; it is declared now because a file imports it. Pinned,
like robolectric and the linters: org.jetbrains.kotlinx is not one of the groups
the prerelease guard covers, so a float here would be free to take a milestone.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
JMR-devandClaude Opus 5
64c1a60a97