[WIP] JS Support

[ankushg]

Work toward #17

Let's get JS support working in here!

To Extract into Separate PRs

• migrate to atomicfu: Use atomicfu instead of kotlin.native.concurrent.AtomicInt in test cases #44
• intermediate sourceset: Create intermediate sourceset to share between Apple and non-Apple targets #45
• make nativeCoroutines JS-friendly
  • migrate tests to kotlinx-coroutines-test: Prepare tests for kotlinx-coroutines-test #46
  • Move Apple-specific tests into appleTest 213f541
  • Rename test functions to support all possible targets 53fa62fa37c5e05d9988f5ce907c11b1c0cdb8ed)[](https://github.com/rickclephas)
• include JS target in nativeCoroutines sourceset Add JS as a target for kmp-nativecoroutines-core #48
• define default CoroutineScope for JS target
• add sample app with regular JS/TS consumer
• update compiler plugin to generate correct native functions/properties
  • split config options into apple and js blocks
  • allow different suffix for Apple and JS

Open Questions

• do we need to add @JsExport? or are the typealiases fine if we just @JsExport the entire class in commonMain? Though we get warnings for this if it has a public suspend fun…
• should the defaultCoroutineScope be different on JS than Native?

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Done in this PR (will be separated into separate PRs)

Main Code

• create supportedTarget as a sourceset between common and apple/js
• created a cross-platform expect fun for freeze()
• created PlatformError as an expect class
  • exposed as NSError on Apple and Throwable on JS
  • create an internal kotlinCause extension that we that we can use instead of digging into userInfo so the tests work on non-Apple platforms

Tests

• switch from Kotlin/Native AtomicInt to atomicfu AtomicInt (extracted to this PR: )
• copied tests from appleTest into supportedTargetTest
  • convert from fun `test method with spaces()` to fun test_method_with_underscores() because JS doesn't support spaces (even with backticks)
  • removed freezing-related tests from supportedTargetTest

Remaining

• figure out how to properly migrate from runBlocking to runTest (from kotlinx-coroutines-test)
  • Tests in supportedTargetTest are passing in JS
  • Tests in supportedTargetTest are currently getting InvalidMutabilityExceptions on Native
  • delete overlapping tests from AppleNative____ tests and only leave freezing ones in there
• update KSP to generate the additional methods on the JS platform

[rickclephas]

An InvalidMutabilityException seems to prevent the conversion to runTest.
Opened an issue: Kotlin/kotlinx.coroutines#3195.

[rickclephas]

some sort of test case of consuming this code?

We should probably add a react client to the sample as discussed in #17 (comment).

do we need to add @JsExport? or are the typealiases fine if we just @JsExport the class?

Not 100% sure, but I think we won't need the @JsExport in the library itself.
We'll definitely need to add those to the generated functions though.