Having a weird issue with Arbs and IOS. Basically ...

# kotest

[Kweku]

Having a weird issue with Arbs and IOS. Basically Using arbs in iOS tests is resulting in an InvalidMutabilityEcception on XorWowRandom.

Something like Arb.long is fine but using it in checkAll for example or doing something like arb.long.take(1) results in the exception

I'm using property testing but not the framework.

[sam]

Probably the random is not thread safe

[Kweku]

Yeah using take where you pass in a RandomSource works so it is possibly to do with the random, but the issue happens on a normal test with no coroutines etc involved

[sam]

are you running any tests in parallel ?

[Kweku]

I don't think so, just running the iOS test via the gutter icon

[Kweku]

Heres the stacktrace

kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen kotlin.random.XorWowRandom@2c52d248
kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen kotlin.random.XorWowRandom@2c52d248
at kotlin.Throwable#<init>(/Users/teamcity1/teamcity_work/11ac87a349af04d5/runtime/src/main/kotlin/kotlin/Throwable.kt:23)
at kotlin.Exception#<init>(/Users/teamcity1/teamcity_work/11ac87a349af04d5/runtime/src/main/kotlin/kotlin/Exceptions.kt:23)
at kotlin.RuntimeException#<init>(/Users/teamcity1/teamcity_work/11ac87a349af04d5/runtime/src/main/kotlin/kotlin/Exceptions.kt:34)
at kotlin.native.concurrent.InvalidMutabilityException#<init>(/Users/teamcity1/teamcity_work/11ac87a349af04d5/runtime/src/main/kotlin/kotlin/native/concurrent/Freezing.kt:22)
at <global>.ThrowInvalidMutabilityException(/Users/teamcity1/teamcity_work/11ac87a349af04d5/runtime/src/main/kotlin/kotlin/native/concurrent/Internal.kt:93)
at <global>.MutationCheck(Unknown Source)
at kotlin.random.XorWowRandom.<set-x>#internal(/Users/teamcity1/teamcity_work/11ac87a349af04d5/backend.native/build/stdlib/kotlin/random/XorWowRandom.kt:20)
at kotlin.random.XorWowRandom#nextInt(/Users/teamcity1/teamcity_work/11ac87a349af04d5/backend.native/build/stdlib/kotlin/random/XorWowRandom.kt:43)
at kotlin.random.Random#nextLong(/Users/teamcity1/teamcity_work/11ac87a349af04d5/backend.native/build/stdlib/kotlin/random/Random.kt:95)
at kotlin.random#[e-mail](/Users/teamcity1/teamcity_work/11ac87a349af04d5/backend.native/build/stdlib/kotlin/random/Random.kt:358)
at io.kotest.property.arbitrary.long$lambda-0#internal(/Users/runner/work/kotest/kotest/kotest-property/src/commonMain/kotlin/io/kotest/property/arbitrary/longs.kt:22)
at io.kotest.property.arbitrary.$long$lambda-0$FUNCTION_REFERENCE$107.invoke#internal(/Users/runner/work/kotest/kotest/kotest-property/src/commonMain/kotlin/io/kotest/property/arbitrary/longs.kt:22)
at io.kotest.property.arbitrary.$long$lambda-0$FUNCTION_REFERENCE$107.$<bridge-BNNN>invoke(/Users/runner/work/kotest/kotest/kotest-property/src/commonMain/kotlin/io/kotest/property/arbitrary/longs.kt:22)
at io.kotest.property.arbitrary.object-8.values$lambda-0#internal(/Users/runner/work/kotest/kotest/kotest-property/src/commonMain/kotlin/io/kotest/property/arbitrary/builders.kt:30)
at io.kotest.property.arbitrary.object-8.$values$lambda-0$FUNCTION_REFERENCE$42.invoke#internal(/Users/runner/work/kotest/kotest/kotest-property/src/commonMain/kotlin/io/kotest/property/arbitrary/builders.kt:30)
at kotlin.sequences.GeneratorSequence.object-1.calcNext#internal(/Users/teamcity1/teamcity_work/11ac87a349af04d5/backend.native/build/stdlib/kotlin/collections/Sequences.kt:591)
at kotlin.sequences.GeneratorSequence.object-1.hasNext#internal(/Users/teamcity1/teamcity_work/11ac87a349af04d5/backend.native/build/stdlib/kotlin/collections/Sequences.kt:609)
at io.kotest.property.Arb#samples(/Users/runner/work/kotest/kotest/kotest-property/src/commonMain/kotlin/io/kotest/property/Gen.kt:85)
at io.kotest.property.arbitrary#[e-mail]<0:0>(/Users/runner/work/kotest/kotest/kotest-property/src/commonMain/kotlin/io/kotest/property/arbitrary/arbs.kt:10)
at io.kotest.property.arbitrary#take$[e-mail]<0:0>

[sam]

Are you passing in your own random

[Kweku]

Passing in a my own Random source and Random works e.g

Arb.long().take(1, RandomSource(Random(1),1))

both in a normal test and a runblocking test

but Arb.long().take() causes an exception

My original usage was just using arbs in checkAll which causes exceptions on IOS. I started calling take to try and work out where the issue was

[sam]

interesting

[sam]

what about if you create that random source first

[sam]

and then try to use it multiple times, in say a loop

[sam]

I don't a mac so I can't test ios, I'm just thinking out loud to help narrow it down

[Kweku]

CheckAll also works if I pass in PropTestConfig with a seed specified

[sam]

Can you create an issue ?

[sam]

I think I know how to fix

[Kweku]

https://github.com/kotest/kotest/issues/2198

[sam]

https://github.com/kotest/kotest/pull/2199

[sam]

I'm hoping that fixes it