Ray Wang - Gnome Accessibility And Automation Testing

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GNOME Accessibility & Automation Testing
A brief introduction to use GNOME Accessibility to do automation test

Ray WangSoftware EngineerNovell / [email protected]

Agenda

What is Accessibility?Definition

AT-SPI

How to use GNOME Accessibility to implement Automation TestAccerciser

LDTP

Orca

Dogtail

Strongwind

What is Accessibility?

Definition

Abbreviation: A11y

Ability to access

Being able to use a Computer regardless of disability or severity of impairment

Wikipediahttp://en.wikipedia.org/wiki/Accessibility

http://en.wikipedia.org/wiki/Computer_accessibility

Other stuff...

Definition

DisabilitiesVisual

Motor & Speech

Hearing

Cognitive

Visual: Common, Age, Large Fonts, High Contrast, Magnification, Screen Reader Motor & Speech: Mild Serious, Ignore False Activation, Specialized or Alternative Input Devices Synthetic SpeechHearing: Mild Serious, SubtitlesCognitive: Reading disorders, Comprehension & Composition Difficulties Speech Recognition Text Highlighting, Careful UI Design, Symbols & Pictures.

AT-SPI

Assistive Technology Service Provider Interface (AT-SPI)

GNOME Accessibility infrastructure

AT-SPIcspi

pyatspi

atk-bridge

registryd

CSPI: The library for C bindingsPyatspi:The Python bindingsatk-bridge: The bridges, of course, need to understand both sides of what it being bridged; so atk-bridge must link to both ATK and AT-SPI.Registryd: Daemon

AT-SPI

Turn on your GNOME Accessibility

AT-SPI

What's happened?

AT-SPI

ApplicationsA11y InfrastructureAssistive Technologies (AT)Divide the view of AT into 3 large components

application layer includes productivity software, desktop tools, window manager, panel, etc; these are the same apps found outside accessibility enabled environments. Also included in the application layer are the GUI toolkits and the APIs necessary to provide accessibility info to the rest of the subsystem. Those APIs may vary among applications and toolkits (i.e. Java, GTK+, mozilla, OpenOffice) but they give adequate information to allow bridging to the common layers below.infrastructure includes what we sometimes call the accessibility subsystem and is what people sometimes just call AT-SPI. We usually use the name AT-SPI more specifically to refer only to the software interfaces and implementations contained in the AT-SPI module; either way, the AT-SPI packages are key parts of the infrastructure layer. The infrastructure layer is what enables assistive technologies to interact consistently with different applications.assistive (or adaptive) technologies are the adapter programs that help the user operate desktop and apps. Examples: GOK, Orca, dasherQ: are features like StickyKeys assistive technologies? A: It depends who you ask; for our purposes we will call them accessibility utilities or platform accessibility features, and use AT to refer to programs that form a direct interface between the end user and the desktop, such as Screen Readers and alternative input systems.

AT-SPI

ApplicationAT-SPI LayerATBridgeApplications and ATs communicate via a layered architecture

We can divide the infrastructure layer into bridge code and AT-SPI; the bridging code connects the applications with the AT-SPI subsystem and therefore can be considered part of the infrastructure.Bridges take accessibility support information (services, events) from within the application and converts it to a common format (in this case, the AT-SPI protocol). Examples: java-access-bridge for GNOME; libatk-bridge. Bridges are important because:Applications on the desktop may implement similar features with a wide variety of code:

Applications are written in different languages (C, Java, python, etc.) and may use different bGUI toolkits to create their interface components (GTK+, Java/Swing, mozilla-gecko, OpenOffice).

Their object models and internal APIs may be very different from one another (Gobject, UNO, mozilla)

This information needs to be shared or exported in a common ABI and via a common IPC protocol. We refer to the code that converts to and from the common format as bridging code.

AT-SPI

ApplicationAT-SPI LayerATBridgeAPI callsEVENTSATs receive events and issue IPC calls

Bridges also listen to application events, for instance AtkObject events which are implemented as Gsignals, and convert them into the appropriate AT-SPI event notifications.

Events may give the AT some information about a change which has occurred in an application, but in many cases the AT needs to make API calls in response to an event in order to update the information it presents to the user. For instance, if focus moves to a new widget, speech and/or braille output may needed to inform the user of this change and in order to create a useful presentation of the newly focused object for the user (either as a spoken words or braille dots); alternatively if GOK is being used and a menu is focused or pops up, GOK may wish to traverse this menu in order to present the new choices to the user as a set of selectable GOK Buttons.

AT-SPI (GNOME)

How GTK+/GNOME Applications connect to AT-SPI

GTK+/GNOME Application

ATK Bridge (libatk-bridge)

ATKGTK+APPAT-SPIATBridge

GNOME applications implement an in-process accessibility API called ATK.

This is bridged to the common AT-SPI layer by the ATK-bridge module.

Atk-bridge exports ATK information via AT-SPI it knows and understands the ATK API, but it doesn't know anything about specific applications or even anything about gtk+.

AT-SPI (GNOME)

GTK+/GNOME Application

ATK Bridge (libatk-bridge)

ATKGTK+

AT-SPI

GAIL

How ATK is implemented for GTK+:The GAIL module

GAIL hooks into ATK and implements ATK interfaces on behalf of GTK+.

GAIL knows about ATK and GTK+, but neither ATK nor GTK+ know about GAIL.

GAIL is dynamically loaded via GTK_MODULES

The ATK implementations for the GTK+ widget set are provided by an extermal library called GAIL (or libgail). It is external for mostly historical reasons, and partly in order to allow alternate implementations to be loaded by specialized applications.

In the diagram above, note that GAIL gets information from GTK+ via public GTK+ API, and uses that information to fulfill the ATK interfaces on behalf of those widgets. For instance the atk-bridge calls ATK API, but the ATK call is redirected through code in libgail which in turn uses gtk+ API calls to provide the corresponding information.

AT-SPI (Java)

Java/Swing Application

Java-access-bridge for GNOME (gnome-java-bridge.jar)

javax.accessibilitySwing

AT-SPI

APPAT-SPIATBridge

Java application use a different bridge

Swing defines a java-specific accessibility API in javax.accessibility

The end result is AT-SPI, just as for GNOME apps (interoperability).

OpenOffice.org have an internal UNO Accessibility API.

Until recently they bridged internally to javax.accessibility; now they bridge to ATK.

Java ATK Wrapper

AT-SPI (Mono)

Winforms

Moonlight

AT-SPI (The Big Picture)

AT-SPI (CORBA DBus)

New AT-SPI (AT-SPI2)at-spi2-core

at-spi2-atk

Report Bugshttps://bugs.freedesktop.org/enter_bug.cgi?product=at-spi2

http://live.gnome.org/Accessibility/BonoboDeprecation

http://www.linuxfoundation.org/en/Accessibility/ATK/AT-SPI/AT-SPI_on_D-Bus

AT-SPI (CORBA DBus)

AT-SPI (CORBA DBus)

How to use GNOME Accessibility to implement Automation Test

Automation Test
Accerciser

Accerciser is An Assistive Technology (AT)

an interactive Python accessibility explorer for the GNOME desktop

uses AT-SPI to inspect and control widgets

allowing you to check if an application is providing correct information to assistive technologies and automated test frameworks.

Accerciser has a simple plugin framework which you can use to create custom views of accessibility information.

Useful AT tool for testing & debugging

http://live.gnome.org/Accerciser

Automation Test
Accerciser

Automation Test
LDTP

Linux Desktop Testing Project

Written in Python

Use python bindings (pyatspi)

Being used byGNOME

Ubuntu

VMware

Palm source

http://ldtp.freedesktop.org/wiki/

Automation Test
Orca

A free, open source scriptable Screen Reader

Written in Python


Could be used in automation testingHas its own test harness

Test samples in the source code (firefox, openoffice, gtk-demo, gcaltool etc)

http://live.gnome.org/Orca

Automation Test
Dogtail

Open source GUI testing tool and automation framework

Written in Python


Being used in some companies

Out of maintain?

Automation Test
Strongwind

GUI test automation framework inspired by dogtail

Written in Python


Human-readable log

http://medsphere.org/community/project/strongwind

Automation Test
Strongwind

How to write a Automation Test by using StrongwindTestable Application

Application Wrapper

Test Script(s)

http://www.mono-project.com/Accessibility:_Strongwind_Basics

Automation Test
Strongwind

Automation Test
Strongwind

Participation

Mailing ListsGNOME [email protected]

GNOME Desktop [email protected]

Accessiblity-at-spiaccessibility-atspi@lists.linux-foundation.org

Mono [email protected]

Irc channel:irc.gnome.org

#a11y

Reference

Python Power Accessibilityhttp://live.gnome.org/Accessibility/PythonPoweredAccessibility

Mono Accessibilityhttp://www.mono-project.com/Accessibility

GNOME Websitehttp://www.gnome.org

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