Page Object Model

A guide to implementing Page Object Model within Maestro

Content

• Introduction

• Login Page example

  • login.js

• Nested example

  • cards.js

• How to structure and tips

  • Folder structure example

  • Ensuring all elements are loaded

    • loadElements.yaml

    • flow.yaml

• Cross-platform example

Introduction

Implementating a Page Object Model has many benefits:

• Improved readability, abstraction and grouping

• Reducing unnecessary duplication

• Improving test/flow maintenance

It allows you to update an element in one place which will then cascade throughout all of your tests/flows. This can save a lot of time when elements are modified and also assist in easier debugging of issues.

Login Page example

login.js

// login.js
output.login = {
    email: 'email_text',
    password: 'password_text',
    loginBtn: 'loginButton',
    registerBtn: 'registerButton'
}

You can then use these variables to reference element IDs, text or even other test data:

- runScript: login.js
- tapOn:
    id: ${output.login.email}
- inputText: "[email protected]"
- tapOn:
    id: ${output.login.password}
- inputText: ${PASSWORD}
- tapOn:
    id: ${output.login.loginBtn}

Nested example

cards.js

// cards.js
output.cards = {
    cardName: 'card_title',
    cardImage: 'card',

    // All Cards Screen
    allCards: {
	createNewBtn: 'btnyam_create',
	cardImage: 'card_image',
	cardName: 'card_title'
    },

    // Virtual Cards
    virtualCards: {
	createNewBtn: 'btn_create',
	cardDetails: {
	    cardNumber: 'card_number',
   	    expiryDate: 'card_expiry'
	}
    }
}

You can create nested element structures to better separate/organise screens and flows. Using the example below, it's easy to define a separate structure for Virtual Cards within the overall Cards object. You could then use them in your flows as follows:

- runScript: cards.js
- tapOn:
    id: ${output.cards.virtualCards.createNewBtn}
- assertVisible:
    id: ${output.cards.virtualCards.cardDetails.cardNumber}

How to structure and tips

Folder structure example

Creating an elements folder is good practice as it allows you to keep all of your element files together.

android/
    cards/
    elements/
	cards.js
	help.js
	home.js
	loadElements.yaml
	login.js
	nav.js
    home/
    login/
iOS/
    cards/
    elements/
	cards.js
	help.js
	home.js
	loadElements.yaml
	login.js
	nav.js
    home/
    login/

Ensuring all elements are loaded

Once you begin creating numerous js files to cover all of your app screens and elements, it can become tricky to remember if you've included the right ones at the start of your test, especially if your flow is crossing multiple areas. A nice trick is to simply add your runScript command once to a single common flow, and then you can run that parent flow once at the start of all your other flows to ensure all of your screens and elements are loaded in correctly.

loadElements.yaml

# loadElements.yaml
appId: com.appid
---
- runScript: cards.js
- runScript: home.js
- runScript: login.js
- runScript: nav.js
- runScript: tabBar.js

Usage:

flow.yaml

appId: com.appID
---
- runFlow: elements/loadElements.yaml
- launchApp
// Test Steps

Using Regular Expressions

Just because you're using a Page Object Model, doesn't mean that you can't take advantage of Maestro's ability to default all text and id selectors as regular expressions. This becomes super-handy for dynamic values or cross-platform rendering differences.

Without POM:

- assertVisible:   # Check that the personalised welcome banner is displayed
    text: 'Welcome back, .*'

With POM:

output.welcomeBanner = 'Welcome back, (.*)'

- assertVisible:   # Check that the personalised welcome banner is displayed
    text: ${output.welcomeBanner}

Cross-platform example

If you have the same app across both Android and iOS but the elements have different IDs, you can employ runFlow with a platform conditional to load in the correct elements.

- runFlow:
    when:
        platform: Android
    commands:
        - runScript:
            file: android_elements/login.js
- runFlow:
    when:
	platform: iOS
    commands:
	- runScript:
	    file: iOS_elements/login.js