Before you start work, you need to study the project and its functionality carefully, keeping in mind the requirements placed on the system and the customer's wishes. Then develop a test plan and prepare all the test documentation you'll be working from going forward.

Keep in mind that the platform on which your app will be published also has its own requirements, and an app that doesn't meet them will be removed or won't be approved for publication. When releasing an app, you need to be sure it meets all of the platform's requirements.

Google Play requirements (Android)

App Store requirements (iOS)

Installation bugs are caused by the huge variety, both in the internals of mobile devices and in firmware versions of, say, Android itself. That's why, in installation testing, you need to keep in mind the many versions of each specific system (whether it's Android, iOS, or even BlackBerry).

A mobile tester needs to keep an eye on changes happening in the world, for example the emergence of new mobile platforms such as Win Mobile OS and Chrome OS.

It's very important to keep in mind the variety of devices that are already on the market and may end up in a user's hands, and to test:

1. Variations of the device types themselves: tablets, phones, players;

2. Different hardware configurations across devices;

3. Variations in device display resolution.

4. Different minor firmware versions

This one is usually pretty simple. The product managers (management) at your company have to define your app's target audience. Your job is to test the app's functionality on every supported version. For example, Apple currently supports iOS versions 8.4.1/ 9.3/ 9.3.1/ 9.3.2

For mobile devices, stressful situations are external interruptions. You need to check that the app handles exceptional situations correctly and doesn't glitch, crash, lose entered data, interrupt transactions, and so on. Here's a minimal checklist of interruptions that

can occur during normal use of the app:

• Incoming and outgoing SMS and MMS
• Incoming and outgoing calls (make sure the app

goes to the background when a call comes in)

• Removing the battery
• Unplugging and plugging in the USB cable
• Turning the network off and on
• Switching from Wi-Fi to 3G/4G and back
• Removing and inserting the SD card
• Turning the media player on and off
• Charging the device
• Push notifications from third-party apps
• The device going to sleep
• Plugging in headphones

Also known as performance testing. This is automated testing that simulates a certain number of users working with some shared resource. It's mostly relevant for online applications (especially mobile online games). For a single-user app, load testing boils down to putting the maximum load on the device with every possible operation in the app, adding the maximum number of items to the home screen, and so on.

We droids are way more productive than humans

We've finally made it to functional testing! It's probably the most important type of testing, and it comes last because its list is the longest :) First and foremost, functional testing is based on your product's requirements, and second (or if, oh horror, there are no requirements) on a mobile functionality checklist. This checklist gathers the main checks and tests that need to be run on a mobile app. So, onward to victory over mobile testing.

• How the app behaves when the device is low on storage (not enough space to install or run the app)
• On a low battery
• Installing to the SD card and to device memory
• Checking that app data is cleaned up when the app is removed from the device
• Working with GPS turned on/off
• Support for the required media files by the given model and OS
• App localization. Check the layout for each language
• Checking that the update behaves properly (all user data is preserved). The app doesn't crash after the update.
• The app's push notifications, and opening them
• Gyroscope sensor: usually this means the horizontal and vertical screen orientation, but some apps respond to position in space more subtly
• Going to the background (minimizing and restoring the app)
• Jumps to social networks, signing up via social networks
• Checking how a single app works with several users at the same time (social networks) in offline/online mode.
• Layout: all elements must be large enough that the user can unambiguously hit them with a finger
• Clickability: every tappable element must have a pressed state (a response to the action)
• Gestures (especially on iPhones). Check the response to two-finger zoom, scroll, rotation, and so on.
• Working with a physical keyboard (if the list of supported models includes any) – line breaks, moving between lines, etc.
• Restoring a purchase (reinstalling after the app was deleted)
• Checking the effect of different date formats, number formats, and system languages
• Make sure the device works in multitasking mode when it needs to
• Check that there is proper navigation between the app's important modules
• Check that error messages are present, for example the message “Network error. Please try again later” when the network isn't working properly
• Make sure the installed app doesn't interfere with the normal operation of other apps and doesn't eat up their memory
• Make sure the app's auto-launch works correctly (if it has one)
• Make sure an accessible user guide exists.

Usability specialist Patrick Cox formulated 10 principles on which

the development of mobile apps and websites should be based.

When testing the design of a mobile version of a website or a mobile app, think in terms of screens, not pages. In his article on mobile design, he writes: “Every screen should include no more than three functions or elements.” It's important to understand that this and the following principles are not a strict criterion, just a recommendation for action. If your app has more than three elements on a page, don't rush to file a bug. It's simply a reason to discuss this design shortcoming with the product manager.

Let's go through all the principles of good mobile usability:

• Screens are not overcrowded
• No highlighted states are used (underlining, bright colors)
• No unfamiliar-looking icons for denoting types

of actions (“add,” “edit,” “back,” “forward,” etc.)

• Text should be in a large font, written simply and clearly
• Scrolling is not used without real need (a scroll

that doesn't scroll anything is a bug)

• Use elements of the site's content for navigation (for example, the logo

contains a link to the home page)

• Don't forget to check your app for user feedback: Messages while content is loading / progress bar Messages when network access fails Messages when trying to delete important information A screen / message at the end of a process / game Sound and vibration notifications that are present and in sync with the on-screen notifications.
• White space in the layout is preserved. Increasing line height makes text easier to read on a mobile device screen.

For functional testing you need at least 2 kinds of device, a phone and a tablet, and for full layout testing you need at least 4 different devices with screens across the range of formats (ldpi > mdpi > hdpi > xhdpi). Each device is tested in two screen orientations, landscape and portrait. The resolutions of these formats are shown in more detail in the diagram:

Android - an operating system for smartphones, internet tablets, e-readers, digital media players, wristwatches, game consoles, netbooks, smartbooks, Google Glass, TVs and other devices. Support for cars and household robots for Android is even planned for the future. The OS is built on the Linux kernel, but has its own implementation of the Java virtual machine from Google. It was originally developed by Android Inc., which was later bought by Google. Google subsequently initiated the creation of the Open Handset Alliance (OHA), which now handles the support and further development of the platform. Android lets you create Java apps that control the device through libraries developed by Google.

86% of the smartphones sold in the second quarter of 2014 ran the Android operating system. Over the whole of 2014, more than 1 billion Android devices were sold.

Popular mobile devices: tablet, phablet, smartphone, player

Most popular resolution for tablets

Windows Phone - a mobile operating system developed by Microsoft, released on October 11, 2010. This operating system is the successor to Windows Mobile, though it is incompatible with it, featuring a completely new interface and, for the first time, integration of Microsoft services: the Xbox Live gaming service and the Zune media player. Unlike its predecessor, Windows Phone is oriented more toward the consumer market than the enterprise sphere.

The new Windows 10 operating system for mobile devices was named “Windows 10 Mobile” instead of Windows Phone 10, and it continues this line, although it echoes the desktop version quite closely. In addition, a universal Windows 10 was released that can run both in tablet mode and in desktop mode.

Smartphones and tablets running Windows Mobile are made by many companies, for example: Samsung, HTC, Nokia, LG, Huawei, and others

* since devices are so diverse, only the main formats are listed

Here are some examples of the tools a mobile app tester needs for working with test devices. They're needed to install test apps on a device, work with files, the device's memory, and more.

The iOS simulator built into the Xcode development environment. To work with it you'll need a Mac. Right now there is no official version for other operating systems. There are only cracks and virtual machines, which are unstable and will cause you a lot of trouble.

In Xcode, the emulator

is located here:

~/Library/Application Support/iPhone

Simulator/6/Applications/<file>

ADB, Android Debug Bridge is a command-line utility included in Google's Android SDK. With this utility you can copy files to the device and back, install and remove apps, perform backup and restore, and much more using commands, run many Linux commands, get bug reports, and so on.

By the way, Android is a branch of the Linux family of systems. Yes, now you can consider yourself a bearded sysadmin and Linux owner : ). Here's a more detailed article on how to set up and install ADB. Below are popular commands for working with your Android from the console through this program.

Runs on the command line.

• adb shell <cmd> - run the command <cmd> in Android
• adb push <local> <remote> - upload a file or directory to the device
• adb pull <remote> [<local>] - copy a file or directory from the device
• adb install < package.apk > - install a package
• adb uninstall <package.apk> - remove an app
• adb connect <ip:port> - connect to Android over the network. Requires some preparation of the device, namely setting up ADB over TCP
• adb logcat [filer] - view the log output in real time. You can set a filter.
• adb backup - make a backup
• adb restore <file> - restore from a backup