Issue#67 Extract OkHttp IdlingResources into a separate module

test-util-android/src/main/java/org/fnives/test/showcase/android/testutil/synchronization/idlingresources/CompositeDisposable.kt

@@ -0,0 +1,19 @@
+package org.fnives.test.showcase.android.testutil.synchronization.idlingresources
+
+class CompositeDisposable(disposable: List<Disposable> = emptyList()) : Disposable {
+
+    constructor(vararg disposables: Disposable) : this(disposables.toList())
+
+    private val disposables = disposable.toMutableList()
+    override val isDisposed: Boolean get() = disposables.all(Disposable::isDisposed)
+
+    fun add(disposable: Disposable) {
+        disposables.add(disposable)
+    }
+
+    override fun dispose() {
+        disposables.forEach {
+            it.dispose()
+        }
+    }
+}

test-util-android/src/main/java/org/fnives/test/showcase/android/testutil/synchronization/idlingresources/Disposable.kt

@@ -0,0 +1,6 @@
+package org.fnives.test.showcase.android.testutil.synchronization.idlingresources
+
+interface Disposable {
+    val isDisposed: Boolean
+    fun dispose()
+}

test-util-android/src/main/java/org/fnives/test/showcase/android/testutil/synchronization/idlingresources/IdlingResourceDisposable.kt

@@ -0,0 +1,19 @@
+package org.fnives.test.showcase.android.testutil.synchronization.idlingresources
+
+import androidx.test.espresso.IdlingRegistry
+import androidx.test.espresso.IdlingResource
+
+class IdlingResourceDisposable(private val idlingResource: IdlingResource) : Disposable {
+    override var isDisposed: Boolean = false
+        private set
+
+    init {
+        IdlingRegistry.getInstance().register(idlingResource)
+    }
+
+    override fun dispose() {
+        if (isDisposed) return
+        isDisposed = true
+        IdlingRegistry.getInstance().unregister(idlingResource)
+    }
+}

test-util-android/src/main/java/org/fnives/test/showcase/android/testutil/synchronization/idlingresources/OkHttp3IdlingResource.kt

@@ -0,0 +1,50 @@
+package org.fnives.test.showcase.android.testutil.synchronization.idlingresources
+
+import androidx.annotation.CheckResult
+import androidx.annotation.NonNull
+import androidx.test.espresso.IdlingResource
+import okhttp3.Dispatcher
+import okhttp3.OkHttpClient
+
+/**
+ * AndroidX version of Jake Wharton's OkHttp3IdlingResource.
+ *
+ * Reference: https://github.com/JakeWharton/okhttp-idling-resource/blob/master/src/main/java/com/jakewharton/espresso/OkHttp3IdlingResource.java
+ */
+class OkHttp3IdlingResource private constructor(
+    private val name: String,
+    private val dispatcher: Dispatcher
+) : IdlingResource {
+    @Volatile
+    var callback: IdlingResource.ResourceCallback? = null
+
+    init {
+        val currentCallback = dispatcher.idleCallback
+        dispatcher.idleCallback = Runnable {
+            callback?.onTransitionToIdle()
+            currentCallback?.run()
+        }
+    }
+
+    override fun getName(): String = name
+
+    override fun isIdleNow(): Boolean = dispatcher.runningCallsCount() == 0
+
+    override fun registerIdleTransitionCallback(callback: IdlingResource.ResourceCallback?) {
+        this.callback = callback
+    }
+
+    companion object {
+        /**
+         * Create a new [IdlingResource] from `client` as `name`. You must register
+         * this instance using `Espresso.registerIdlingResources`.
+         */
+        @CheckResult
+        @NonNull
+        fun create(@NonNull name: String?, @NonNull client: OkHttpClient?): OkHttp3IdlingResource {
+            if (name == null) throw NullPointerException("name == null")
+            if (client == null) throw NullPointerException("client == null")
+            return OkHttp3IdlingResource(name, client.dispatcher)
+        }
+    }
+}