add documentation for the usage with jest

Closes #143
Heavily inspired by the solution of @AlanFoster and with the help of @levito

docs/Guide.Jest.md

@@ -0,0 +1,57 @@
+# Jest as Test Runner
+
+## Usage
+
+### 0. Use the [Getting Started](Introduction.GettingStarted.md) Guide to set up detox
+
+Except that you need to skip the install mocha step.
+
+### 1. Install Jest
+
+```sh
+npm install --save-dev jest
+```
+
+### 2. Remove mocha specific files
+
+You should remove `e2e/mocha.opts`, you no longer need it.
+
+### 3. Write a detox setup file
+
+```js
+const detox = require('detox');
+const config = require('../package.json').detox;
+
+// Set the default timeout
+jasmine.DEFAULT_TIMEOUT_INTERVAL = 120000;
+
+beforeAll(async () => {
+  await detox.init(config);
+});
+
+afterAll(async () => {
+  await detox.cleanup();
+});
+
+// optional, you may remove this part
+beforeEach(async () => {
+  await device.reloadReactNative();
+});
+```
+
+### 4. Run jest
+
+Add this part to your package.json
+```json
+"scripts": {
+    "test:e2e": "jest e2e --setupTestFrameworkScriptFile=./jest/setup-e2e-tests.js"
+}
+```
+
+
+> Side Note: Don't worry about mocks being used, detox works on the compiled version of your app.
+
+## How to run unit test and E2E tests in the same project
+
+- If you have a setup file for the unit tests pass it into jest by passing `--setupTestFrameworkScriptFile=./path/to/setup-unit-tests.js` to your jest unit test call. You need to remove this option from your `jest` configuration in the package.json.
+- Call your E2E tests like mentioned above

docs/README.md

@@ -36,6 +36,7 @@
 - [Debugging Apps in Xcode During a Test](Guide.DebuggingInXcode.md)
 - [Advanced Mocking With Detox](Guide.Mocking.md)
 - [Migration Between Detox Versions](Guide.Migration.md)
+- [Use Jest as Test Runner](Guide.Jest.md)
 
 ## Under The Hood