add documentation for the usage with android

This should enable other users to use android more
easily as the current status configuration can be
quite confusing.

Build with the help of @AppsThatMatter

Relates to #96

docs/Introduction.Android.md

@@ -0,0 +1,63 @@
+# Adding Android
+
+## Setup
+
+### 0. Do the initial setup described in the Getting Started Guide
+
+### 1. Add the detox Android project as an androidTestCompile dependency
+
+You need to add this into your `android/settings.gradle`:
+```gradle
+include ':detox'
+project(':detox').projectDir = new File(rootProject.projectDir, '../node_modules/detox/android/detox')
+```
+
+> In case your project’s RN version is at least 0.46.0 change the oldOkhttp configuration string to newOkhttp, in the `app/build.gradle` here.
+
+In the `android/app/build.gradle` you need to add this into your dependencies section:
+
+```gradle
+androidTestCompile(project(path: ":detox", configuration: "newOkhttpDebug"), {
+    exclude group: 'com.android.support', module: 'support-annotations'
+})
+```
+
+### 2. Introduce [Espresso](https://developer.android.com/training/testing/espresso/index.html) test runner
+
+Detox Android is a standard Android integration test. Although, it is completely asynchronous.
+
+It uses Espresso internally, therefore you have to use an AndroidJUnitRunner as your test runner (or a subclass of it).
+For this you need to modify your `android/app/build.gradle`:
+
+```gradle 
+android {
+    defaultConfig {
+        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+    }
+}
+```
+
+### 3. Create Android Test class
+
+You need to add the file `android/app/src/androidTest/java/com/[your.package]/DetoxTest.java` and fill it like [this](../detox/test/android/app/src/androidTest/java/com/example/DetoxTest.java), expect that you need to change the package to your projects name.
+
+### 4. Add Android configuration
+
+Add this part to your `package.json`:
+
+```json
+"detox": {
+    "configurations": {
+        "android.emu.debug": {
+            "binaryPath": "android/app/build/outputs/apk/app-debug.apk",
+            "build": "pushd android && ./gradlew assembleDebug assembleAndroidTest -DtestBuildType=debug && popd",
+            "type": "android.emulator",
+            "name": "Nexus_5X_API_25"
+        }        
+    }
+}
+```
+
+### 5. Run the tests
+
+For this you need to specify the configuration (if you have a second one already) like this: `detox test -c android.emu.debug`

docs/README.md

@@ -4,6 +4,7 @@
 
 - [Getting Started](Introduction.GettingStarted.md)
 - [Writing You First Passing Test](Introduction.WritingFirstTest.md)
+- [Adding Android](Introduction.Android.md)
 - [How Detox Works](Introduction.HowDetoxWorks.md)
 - [Recommended Workflows With Detox](Introduction.Workflows.md)