Picking The Right Set of Mobile Devices
By Brian KitchenerSoftware Quality [email protected]
Overview• About me• Some Background• The Problem• Understanding Android• How Apps Work• Building a Device Matrix• Example Matrices• Conclusion
About Me• Software Quality Architect at ProtoTest
• We're a mobile test lab that combines usability testing with quality assurance to cultivate a great user experience
• Project Architect, Technical Lead, Trainer.
• Started in QA in 2001• BA in Applied Computing from University of Denver• Testing background : Functional, Performance, UAT,
Security, API, Database.• Automation : Selenium, WebDriver, WatiN, MonkeyTalk,
SOASTA, Fitnesse, QTP, EggPlant, Squish• Languages : C#, Java, Ruby, Javascript
BACKGROUND INFORMATION
Some Stats for 2012• Mobile Apps achieved $17 billion in sales• 5.2 Mobile Subscribers– 1.2 Billion PC’s– 4.2 Billion people use a toothbrush– 1 Billion Smartphones
• 722 Million Smartphones sold • 1.4 Million iOS + Android Apps• 25 developers = half of app revenue
iPhone - June 2007
About the iPhone• Steve Ballmer : Microsoft CEO
– “There’s no chance the iPhone is going to gain significant market share. No chance.”
• Patrick Stewart: – “Last Wednesday, I stupidly dropped my iPhone in the bath, and my life
has sort of spiraled almost out of control.”• Jon Rubinstein – Palm CEO
– Is there a toaster that also knows how to brew coffee? There is no such combined device, because it would not make anything better than an individual toaster or coffee machine. It works the same way with the iPod, the digital camera or mobile phone: it is important to have specialized devices.
• Mike Lazaridis – Blackberry CEO– And so what [the iPhone] has actually done is increased our sales.
ANDROID IS THE PROBLEM
And Then There Were Two…• Android unveiled November 2007• First device was sold in October
2008.• Over 11,000 models have been
released.• 48 Billion app installs• Over 1 Billion Android devices
activated• 8 OS Revisions
OS Fragmentation
Device Fragmentation
Let’s do some math!• 16 device display categories• 20 different common resolutions• 8 OS versions• 6 Hardware Manufacturers• 4 Major cellular networks• 16 x 20 x 8 x 6 x 4 = 76,800 permutations• Pairwise approach = over 30 permutations• Who can afford to increase testing by 30X?
Our Approach • Efficiency, not coverage• Flexible: support small or large number of devices• Understand how apps work to logically select criteria• Use Market research to pick most common
configurations• Pick minimum and maximum boundary values for each
criteria• Choose a value that matches an edge case or abnormal
configuration.• Pick values that stress or tax the system
UNDERSTANDING ANDROID
Android• Built and Maintained by Google• Open Source• Built on Linux kernel• ARM• X86 Ports• Built to support almost any type of device– Phones, tablets, phablets, media players, tv’s,
watches, etc.• Device Manufacturers customize code.
Example: Kindle Fire• Forked Android 2.3– Not updateable
• Customized UI• Separate App store• Not all android apps work• Custom web browser
The Operating System• Google Releases “stock”
versions• 10 Major Releases since
2008– API Level, not Version
• Device manufacturers like to customize the OS– Drivers, libraries, UI
• “Stock” OS available in Nexus devices or an Emulator
Simulators / Emulators• Simulator imitates the software layer – OS and Libraries– Apple provides a simulator in xCode IDE
• Emulator duplicates the hardware and software– Processor and Memory– Cannot mimic GPU, GPS, accelerometer
• Always run stock OS• Can be used to test some functionality• Should always test on a physical device too
The Processor• ARM RISC-based instruction set• Specification defined by ARM holdings• 32 bit• Same as iOS• X86 patches and ports• It’s only a spec, can be modified.
SoC – System On A Chip• Main Board• Processor• RAM Bus • GPU • May include : – Cellular– WiFi– NFC– GPS– Bluetooth
2 Samsung Galaxy S4sQuallcomm Snapdragon• Quallcomm Krait 300– Quad core ARMv7
Cortex A15 Architecture
• Adreno 320 GPU • Dual Channel 533Mhz
Bus• Integrated LTE
Samsung Exynos 5 Octa• Samsung Big.little
processor– Quad core Cortex A 15– Quad core Cortex A7
• PowerVR SGX 544 GPU• Dual Channel 800Mhz
Bus• No Integrated LTE
Common SoCManufacturer Device Name Cores Processor GPU
Qualcomm Snapdragon S4 2 or 4 ARM Cortex-A15 Adreno
Nvidia Tegra 3 4+1 ARM Cortex-A9 Geforce
Samsung Exynos 4 2 or 4 ARM Cortex-A9 Mali
Intel Medfeld 1 Intel x86 PowerVR
Texas Instruments OMAP 4 2+2 ARM Cortex
A9 PowerVR
ST-Ericcson NovaThor 2 ARM Cortex-A9 PowerVR
Resolution is not enough• Unlimited number of screen sizes available• Screens range from 3” to 11”• Each screen has a resolution, same as a
monitor– If you increase the resolution everything shrinks!
• Pixels per Inch = Density• Screen Size + Density = Display Bucket• Resolution is not enough!
The Display BucketsSize : • Xlarge : 8” - 10” tablet. • Large : 5” - 7” tablet. • Normal : 3.5” - 5” phones.• Small : 3” - 3.5” phones. Density :• ldpi = Low DPI (~120)• mdpi = Medium DPI (~160)• hdpi = High DPI (~240)• xhdpi = Extra High DPI
(~320)
Low density (120), ldpi
Medium density (160), mdpi
High density (240), hdpi
Extra high density (320), xhdpi
Small screen
QVGA (240x320)
480x640
Normal screen
WQVGA400 (240x400)WQVGA432 (240x432)
HVGA (320x480)
WVGA800 (480x800) WVGA854 (480x854) 600x1024
640x960
Large screen
WVGA800** (480x800) WVGA854** (480x854)
WVGA800* (480x800) WVGA854* (480x854) 600x1024
Extra Large screen
1024x600 WXGA (1280x800)†
1024x7681280x768
1536x11521920x1152 1920x1200
2048x15362560x1536 2560x1600
Display Buckets• Galaxy S3
– 1280 x 720– Xhdpi density (331ppi)– Normal screen (4.7”)
• Galaxy Tab 10.1– 1280 x 800 – ldpi density (149ppi)– Xlarge sceren (10.1”)
• Galaxy Note LTE – 1280 x 800– hdpi density (285ppi)– Large Screen (5.5”)
Market Analysis
Aspect Ratio• UI is manipulated from code• Density Pixels adjust for screen size– But can use regular pixels!
• Need to take both X and Y into account!– Easy to overlap or hide things
• Includes orientation• Some devices include an aspect ratio changer!
(LG Optimus Vu)
Cellular Carrier• Four Major US Networks– Verizon, Sprint, AT&T, T-Mobile– Some phone interoperability– 2 protocols
• GSM – T-Mobile AT&T• CDMA – Verizon and Sprint
– Carriers assigned specific frequency bands– LTE will be new standard - But spectrum issues will prevent
cross-network phones• So if the phone supports the carrier’s protocol and
band it can theoretically connect.
HOW APPS WORK
How Apps work• Apps need to work on all screen sizes– May not be functional– May be wasted space– May not make sense
• Apps define XML layouts similar to HTML– Node structure– Static Content – Images, etc– Dynamic Content – Color, Text, etc.
Layouts and Fragments• XML Fragments are
reusable components• Layouts stitch together
fragments for a specific sized device
• App may need different flow for tablet vs phone
BUILDING THE DEVICE MATRIX
Our Criteria• Operating System
– OS customizations, missing libraries, driver issues, • Screen Size
– Rendering issues, usability, missing layouts• Pixel Density
– Density Independence, missing layouts.• Aspect Ratio
– X,Y calculations, overlapping panels, display issues• SoC
– Hardware performance, Instruction set, battery, signal• Carrier
– Network protocol, speed, responsiveness, packet loss
The Goal• Efficiency, not coverage!• Build a set of devices to be used for app and
website testing.• Know when to update them• Define a list of simple categories of devices• Pick devices that offer broad coverage• Adjust the number of devices based upon
needed coverage
Categorical Approach• Define scope– Android, iOS, phone, tablet, etc.
• Understand Testing requirements• Self-descriptive Names• Help to broaden coverage• Will adjust devices chosen to cover our criteria• Should be apparent when to update a device• Spread coverage :– Usage -> Edge Cases -> Strange -> Stress
Example Categories• Common
– Matches most common display configuration
• Newest– Latest OS version, largest
screen, highest resolution
• Oldest– Oldest, slowest, smallest
device.
• Abnormal– Non-standard OS, aspect
ratio, orientation, size
• Popular– Most popular device in
terms of sales
• Budget– Low-priced new model.
Tend to have strange specs
• Flagship– Nexus device running
stock Android OS
• Catch-All– Cover any missing criteria
Android Phone Matrix March 2012
Device Name OS Display Aspect
SoC Carrier
Newest HTC Droid DNA 4.2 Normal-xhdpi 9:16 Snapdragon S4 Verizon
Oldest HTC Tattoo 1.6 Small-ldpi 3:4 Snapdragon S1 AT&T
Common Motorola Droid 3 2.3 Normal-hdpi 9:16 TI OMAP 4 Verizon
Popular Samsung Galaxy S3
4.1 Normal-xhdpi 9:16 Exynos 4 Sprint
Abnormal LG Optimus VU 4 Large-hdpi 3:4 Nvidia Tegra 3 Tmobile
Flagship LG Nexus 4 4.2 Normal-xhdpi 3:5 Snapdragon S4 TMobile
Budget Dell Venue 2.2 Normal-mdpi 3:5 Snapdragon S3 AT&T
Catch-All Sony Xperia P 2.3 Normal-hdpi 9:16 Sony NovaThor AT&T
iOS Matrix March 2012
Device Name
OS Display Aspect SoC Carrier
Newest iPhone 5S 7 4” 1136 x 640 326ppi 9:16 Apple 64bit A7 T-Mobile
Oldest iPhone 3g 6 3.5” 320 x 480 165ppi 2:3 Apple A3 AT&T
Common iPhone 5 6 4” 1136 x 640 326ppi 9:16 Apple A5 Verizon
Popular iPhone 4 6 3.5” 640x960 330ppi 2:3 Apple A4 Sprint
iPad (Retina)
iPad 3 7 10” 1536x2048 264ppi 3:4 Apple A5X Verizon
iPod iPod Touch (4th gen)
5 3.5” 640x960 326ppi 2:3 Apple A4 WiFi
Mini iPad Mini 6 7” 1024 x 768 162ppi 3:4 Apple A5 AT&T
Conclusion• Understanding how everything works allows us
to logically select devices.• A large number of permutations can be covered
in few devices• If additional coverage is needed additional
devices can be added• White Paper : – http://www.prototest.com : – Building the Ultimate Device Matrix