Issue#67 Extract InstantExecutorExtension

test-util-junit5-android/.gitignore

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+/build

test-util-junit5-android/build.gradle

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+plugins {
+    id 'com.android.library'
+    id 'org.jetbrains.kotlin.android'
+}
+
+android {
+    compileSdk 31
+
+    defaultConfig {
+        minSdk 21
+        targetSdk 31
+
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+        consumerProguardFiles "consumer-rules.pro"
+    }
+
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+    }
+    compileOptions {
+        sourceCompatibility JavaVersion.VERSION_1_8
+        targetCompatibility JavaVersion.VERSION_1_8
+    }
+    kotlinOptions {
+        jvmTarget = '1.8'
+    }
+}
+
+dependencies {
+    implementation "org.junit.jupiter:junit-jupiter-engine:$junit5_version"
+    implementation "androidx.arch.core:core-runtime:$arch_core_version"
+}

test-util-junit5-android/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+#-keepattributes SourceFile,LineNumberTable
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile

test-util-junit5-android/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="org.fnives.test.showcase.android.testutil">
+
+</manifest>

test-util-junit5-android/src/main/java/org/fnives/test/showcase/android/testutil/InstantExecutorExtension.kt

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+package org.fnives.test.showcase.android.testutil
+
+import android.annotation.SuppressLint
+import androidx.arch.core.executor.ArchTaskExecutor
+import androidx.arch.core.executor.TaskExecutor
+import org.junit.jupiter.api.extension.AfterEachCallback
+import org.junit.jupiter.api.extension.BeforeEachCallback
+import org.junit.jupiter.api.extension.ExtensionContext
+
+/**
+ * Junit5 Version of InstantTaskExecutorRule from Junit4
+ *
+ * reference: https://developer.android.com/reference/androidx/arch/core/executor/testing/InstantTaskExecutorRule
+ *
+ * A JUnit5 Extensions that swaps the background executor used by the Architecture Components with a different one which executes each task synchronously.
+ * You can use this extension for your host side tests that use Architecture Components.
+ */
+@SuppressLint("RestrictedApi")
+class InstantExecutorExtension : BeforeEachCallback, AfterEachCallback {
+
+    override fun beforeEach(context: ExtensionContext?) {
+        ArchTaskExecutor.getInstance()
+            .setDelegate(object : TaskExecutor() {
+                override fun executeOnDiskIO(runnable: Runnable) = runnable.run()
+
+                override fun postToMainThread(runnable: Runnable) = runnable.run()
+
+                override fun isMainThread(): Boolean = true
+            })
+    }
+
+    override fun afterEach(context: ExtensionContext?) {
+        ArchTaskExecutor.getInstance().setDelegate(null)
+    }
+}