Issue#67 Extract IdlingResources helpers into a separate module

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

@@ -0,0 +1,39 @@
+package org.fnives.test.showcase.android.testutil.synchronization.idlingresources
+
+import androidx.test.espresso.IdlingRegistry
+import androidx.test.espresso.IdlingResource
+import org.fnives.test.showcase.android.testutil.synchronization.loopMainThreadFor
+import java.util.concurrent.Executors
+
+// workaround, issue with idlingResources is tracked here https://github.com/robolectric/robolectric/issues/4807
+fun anyResourceIdling(): Boolean = !IdlingRegistry.getInstance().resources.all(IdlingResource::isIdleNow)
+
+fun awaitIdlingResources() {
+    val idlingRegistry = IdlingRegistry.getInstance()
+    if (idlingRegistry.resources.all(IdlingResource::isIdleNow)) return
+
+    val executor = Executors.newSingleThreadExecutor()
+    var isIdle = false
+    executor.submit {
+        do {
+            idlingRegistry.resources
+                .filterNot(IdlingResource::isIdleNow)
+                .forEach { idlingResource ->
+                    idlingResource.awaitUntilIdle()
+                }
+        } while (!idlingRegistry.resources.all(IdlingResource::isIdleNow))
+        isIdle = true
+    }
+    while (!isIdle) {
+        loopMainThreadFor(200L)
+    }
+    executor.shutdown()
+}
+
+private fun IdlingResource.awaitUntilIdle() {
+    // using loop because some times, registerIdleTransitionCallback wasn't called
+    while (true) {
+        if (isIdleNow) return
+        Thread.sleep(100L)
+    }
+}