OkHttpIdlingResource in Kotlin

OkHttpIdlingResource.kt

import androidx.annotation.CheckResult
import androidx.annotation.NonNull
import androidx.test.espresso.IdlingResource
import okhttp3.Dispatcher
import okhttp3.OkHttpClient

class OkHttpIdlingResource private constructor(
  private val resourceName: String, private val dispatcher: Dispatcher
) : IdlingResource {
  companion object {
    fun create(
      @NonNull name: String,
      @NonNull client: OkHttpClient
    ): OkHttpIdlingResource {
      return OkHttpIdlingResource(name, client.dispatcher)
    }
  }

  @Volatile
  var resourceCallback: IdlingResource.ResourceCallback? = null

  init {
    dispatcher.idleCallback = Runnable { resourceCallback?.onTransitionToIdle() }
  }

  override fun getName(): String = resourceName

  override fun isIdleNow(): Boolean = dispatcher.runningCallsCount() == 0

  override fun registerIdleTransitionCallback(callback: IdlingResource.ResourceCallback?) {
    resourceCallback = callback
  }
}