Solution: Mocking library
import org.junit.Test
import java.lang.reflect.Method
import java.lang.reflect.Proxy
import kotlin.reflect.KClass
import kotlin.test.assertEquals
import kotlin.test.assertNotNull
class MockRegistry {
inline fun <reified T : Any> mock(): T = mock(T::class)
private var recording = false
private var bodyToStore: (() -> Any?)? = null
private var handlers = mutableMapOf<Record, () -> Any?>()
inline fun <reified T: Any> mock(): T = mock(T::class.java)
fun <T : Any> mock(classRef: KClass<T>): T {
val proxy = Any()
return Proxy.newProxyInstance(
classRef.java.classLoader,
arrayOf(classRef.java)
) { _, method, args ->
val record = Record(proxy, method, args?.toList())
if (recording) {
handlers[record] = checkNotNull(bodyToStore)
throw RecordedCorrectlyException()
} else {
checkNotNull(handlers[record]) { "No recording..." }
.invoke()
}
} as T
}
fun <T> setBody(functionCall: () -> T, body: () -> T) {
try {
recording = true
this.bodyToStore = body
functionCall()
} catch (e: RecordedCorrectlyException) {
// no-op
} finally {
recording = false
this.bodyToStore = null
}
}
fun <T> setReturnValue(functionCall: () -> T, value: T) {
setBody(functionCall) { value }
}
class RecordedCorrectlyException : RuntimeException()
data class Record(
val proxy: Any,
val method: Method,
val arguments: List<Any?>?,
)
}
