Can you use shared resources for tests in a Kotlin...

# multiplatform

[José González Gómez]

Can you use shared resources for tests in a Kotlin Multiplatform Mobile project? I tried to include some JSON files under src/commonTest/resources but they don't seem to get copied to the output directory when running Android tests. Putting them under src/androidTest/resources did the trick for Android tests, but I don't want to have two copies of these files, as they are common for both Android and iOS tests.

[Derek Ellis]

I wrote this to make use of test resources in common tests: https://gist.github.com/dellisd/a1df42787d42b41cd3ce16f573984674

It reads them from the commonTest/resources directory, but in a lot of cases that's good enough.

[José González Gómez]

thanks!

[Nicolas Verinaud]

Creating symbolic links might also do the trick. 🙂

[José González Gómez]

🤔 I'm afraid we've got too many Windows machines hanging around for Android development...

[Michal Klimczak]

Oh, I was just wondering about the same thing yesterday, but I don't have idea how to approach this with iosTest target. https://kotlinlang.slack.com/archives/C3SGXARS6/p1620045905289200?thread_ts=1620045905.289200&cid=C3SGXARS6

[Michal Klimczak]

I just had a massive ide issue around using androidTest/resources. In case anyone has the same: https://kotlinlang.slack.com/archives/C3PQML5NU/p1620201399394700?thread_ts=1620195839.390000&cid=C3PQML5NU

[José González Gómez]

Ok, I finally managed to do it, although there are some cases that still don't work... I put the shared test resources under commonTest/resources, and then add the following snippet in the shared project's `build.gradle.kts`:

afterEvaluate {
    listOf("debug", "release").forEach { variant ->
        val copyTaskName = "copyResources${variant.capitalize()}UnitTest"
        tasks.register<Copy>(copyTaskName) {
            from("$projectDir/src/commonTest/resources")
            into("$buildDir/tmp/kotlin-classes/${variant}UnitTest/")
        }
        tasks.getByName("test${variant.capitalize()}UnitTest") {
            dependsOn(copyTaskName)
        }
    }

    tasks.register<Copy>("copyResourcesIosX64DebugTest") {
        from("$projectDir/src/commonTest/resources")
        into("$buildDir/bin/iosX64/debugTest/")
    }
    tasks.getByName("iosX64Test") {
        dependsOn("copyResourcesIosX64DebugTest")
    }
}

and then I have a `expect`/`actual` class to load resources:

expect class TestResource(path: String) {
    val content: String?
}

actual class TestResource actual constructor(path: String) {
    actual val content: String? = NSString.stringWithContentsOfFile(NSBundle.mainBundle.pathForResource(path, null)!!) as String?
}

actual class TestResource actual constructor(path: String) {
    actual val content: String? = this::class.java.classLoader?.getResource(path)?.readText()
}

Be careful! The into directories seem to change depending on the Android Studio / Gradle version

[José González Gómez]

Maybe somebody with more Gradle experience than me can help with this... with this solution the first time I execute ./gradlew testDebugUnitTest after a ./gradlew clean the build fails because the files aren't copied to the destination. The second time the files are copied and the build is successful. I thought that maybe the copy task doesn't create the target directory, so I tried to manually create it before executing the tests, but this didn't work

[José González Gómez]

found the culprit, the Kotlin compilation deletes the destination directory, so the copy task must be run after them:

// Top of build.gradle.kts
import org.jetbrains.kotlin.gradle.tasks.KotlinCompile

// Inside the task definition
        tasks.register<Copy>(copyTaskName) {
            ...
            mustRunAfter(tasks.withType<KotlinCompile>())
        }

[goncalossilva]

Inspired by this discussion (and @Derek Ellis’s gist!), I’ve open-sourced goncalossilva/kotlinx-resources 🙂