Easy Functional and Integration Testing with Mock Server | Tutorial and Example

Basic Testing

1. Unit test - making sure each function/unit of code works as expected

2. Functional test - making sure units interact with each other as expected

3. Integration test - making sure our app integrate with other app/api/services as expected

Why Use Mock Server

1. Reuse

2. Reducing Dependency of API

3. Debugging

4. Predictability and Consistency

What is Mock Server

How to Use Mock Server

Basic Node & Express

$ mkdir mock
$ cd mock

$  yarn init
yarn init v0.16.1
question name (mock2):
question version (1.0.0):
question description:
question entry point (index.js):
question git repository:
question author:
question license (MIT):
success Saved package.json
✨  Done in 59.45s.

$ yarn add express morgan

$ vim app.js

// 1
const express = require('express'),
app = express(),
morgan = require('morgan');

// 2
app.use(morgan('dev'));

// 3
app.get('/', function (req, res) {
  res.send('Hello World!');
});

// 4
app.listen(5678, function () {
   console.log('listening on port 5678!');
});

1. Here we tell Node that we require Express and Morgan, and that we assign app constant to the express module

2. We tell Express to use Morgan with the profile 'dev'

3. We tell Express to send 'Hello World!' when a GET request is sent to '/'

4. Lastly we tell Express to listen to port 5678 and prints a console log with that message

GET / 200 2.518 ms - 12

Favourite Food app

Mock server for Favourite Food

app.get('/3l2z2', function (req, res) {
  let favJson = {
    "foo": "Pizza",
    "bar": "Roast Pork Knuckle"
  };
  res.send(favJson);
});

const express = require('express'),
app = express(),
morgan = require('morgan');

app.use(morgan('dev'));

app.get('/', function (req, res) {
  res.send('Hello World!');
});

app.get('/3l2z2', function (req, res) {
  let favJson = {
    "foo": "Pizza",
    "bar": "Roast Pork Knuckle"
  };
  res.send(favJson);
});

app.listen(5678, function () {
  console.log('listening on port 5678!');
});

{"foo":"Pizza","bar":"Roast Pork Knuckle"}

Intro to UI Test

func testFoo() {
  let textField = app.textFields["tf"]  // 1
  textField.tap()                       // 2
  textField.typeText("foo")             // 3
  app.buttons["Calculate"].tap()        // 4
  expectation(for: exists, evaluatedWith: app.staticTexts["Pizza"], handler: nil)
  waitForExpectations(timeout: 3, handler: nil) //5
}

1. Find the text field with accesibility label tf

2. Taps the field to bring up keyboard

3. Types foo

4. Taps the calculate button

5. Waits for 3 second for the app to show Pizza text

Simple Express Refactor

$ mkdir controllers
$ cd controllers
$ touch fav.js

exports.index = (req, res) => {
  let favJson = {
    "foo": "Pizza",
    "bar": "Roast Pork Knuckle"
  };
  res.send(favJson);
};

app.get('/3l2z2', function (req, res) {
  let favJson = {
    "foo": "Pizza",
    "bar": "Roast Pork Knuckle"
  };
  res.send(favJson);
});

const favController = require('./controllers/fav');

app.get('/3l2z2', favController.index);

Summary

• Why, What, How of mock server

• UITest in iOS

• Node + Express app to act as mock server

• Refactor Express

• Using schemes in Xcode to manage multiple URLs

• Using Fastlane to run tests against mock server on CI server