Kotlin: unit test assert object after gson

Question

I have JUnit test like that:

Test fun testCategoriesLoading() {
    val subscriber = TestSubscriber<List<ACategory>>()
    service.categories().subscribe(subscriber)

    subscriber.awaitTerminalEvent()

    subscriber.assertNoErrors()
}

service is Retrofit, that uses GsonConverter to deserialize json into

data class ACategory(val id: String, val title: String, val parentId: String?, val hasChildren: Boolean)

instances.

Test is passing, even if ACategory filled with id = null, title = null etc.

So, as far as i know, gson using reflection, and kotlin lazily resolves this nullability constraints on first access.

Is there any way to force this resolve? Some good-looking solution without direct access to fields manually? I really don't want to write every assert by hand.

Answer 1

You could use the new Kotlin reflection. If you have an instance of ACategory, call

ACategory::class.memberProperties
        .filter { !it.returnType.isMarkedNullable }
        .forEach {
            assertNotNull(it.get(aCategory))
        }

to access all properties that are marked as not nullable and assert they're not null. Make sure, you have the reflection lib on the classpath.

Make sure you're using M14.