GWT Open Source Project

Clone this repo:
  1. 94e4597 Fix generatePreamble that was broken in c71242 by Goktug Gokdogan · 6 hours ago master
  2. 803135b Small refactor in JsObjectLiteral. by Roberto Lublinerman · 6 days ago
  3. 00218d4 Simplify RuntypeTypeId generation. by Roberto Lublinerman · 7 days ago
  4. 5c79867 Small refactor in JsFunction. by Roberto Lublinerman · 7 days ago
  5. ed6a4df Avoid static initializers for native JsType and JsFunction. by Roberto Lublinerman · 7 days ago


GWT is the official open source project for GWT releases 2.5 and onwards.

In this document you have some quick instructions to build the SDK from source code and to run its tests.

For a more detailed documentation visit our web site. If you are interested in contributing with the project, please read the Making GWT better section.

Building the GWT SDK:

  • In order to build GWT, java and ant are required in your system.

  • Optional: if you want to compile elemental you need python and g++ installed.

  • You need the gwt-tools checked out and up-to-date, and it will be placed by default at ../tools. You can override the default location using the GWT_TOOLS environment variable or passing argument to ant.

Note: that you need svn to checkout gwt-tools

  • To create the SDK distribution files run:

$ ant clean elemental dist-dev

or if you don’t have python and g++ just run

$ ant clean dist-dev

Then you will get all .jar files in the folder build/lib and the redistributable file will be: build/dist/

if you want to specify a different version number run:

$ ant elemental clean dist-dev -Dgwt.version=x.x.x

  • To compile everything including examples you have to run

$ ant clean elemental dist

How to verify GWT code conventions:

  • In GWT we have some conventions so as all code written by contributors look similar being easier to review.

  • After you make any modification, run this command to compile everything including tests, to check APIs, and to verify code style. It shouldn’t take longer than 3-4 minutes.

$ ant compile.tests apicheck checkstyle -Dprecompile.disable=true

How to run GWT tests

  • Previously to run any test you have to set some environment variables to guarantee that they are run in the same conditions for all developers.

In a Unix like platform you can use the export command:

$ export TZ=America/Los_Angeles ANT_OPTS=-Dfile.encoding=UTF-8

But in Windows™ you have to set the time-zone in your control panel, and the environment variables using the command set.

  • Finally you can run all test suites with the following command, but be prepared because it could take hours, and probably it would fail because of timeouts, etc.

$ ant test

  • Thus, you might want to run only certain tests so as you can focus on checking the modifications you are working on.

GWT build scripts use specific ant tasks and a bunch of system properties listed in the following table to specify which tests to run and how.

For instance to run the task test in the module user you have to change to the user folder and run ant with the task as argument, adding any other property with the -D flag:

$ ( cd user && ant test -Dtest.emma.htmlunit.disable=true ; cd .. )

Module         | Task                   | Property to skip
-------------- | ---------------------- | ----------------
dev            | test                   |
codeserver     | test                   | test.codeserver.disable
user           | test                   | test.user.disable
user           | test.nongwt            | test.nongwt.disable
user           |      |
user           | test.web.htmlunit      | test.web.htmlunit.disable
user           | test.draft.htmlunit    | test.draft.htmlunit.disable
user           | test.nometa.htmlunit   | test.nometa.htmlunit.disable
user           | test.emma.htmlunit     | test.emma.htmlunit.disable
user           | test.coverage.htmlunit | test.coverage.htmlunit.disable
user           |      |
user           | test.web.selenium      | test.web.selenium.disable
user           | test.draft.selenium    | test.draft.selenium.disable
user           | test.nometa.selenium   | test.nometa.selenium.disable
user           | test.emma.selenium     | test.emma.selenium.disable
requestfactory | test                   |
elemental      | test                   |
elemental      | test.nongwt            |
elemental      |      |
elemental      | test.web.htmlunit      |
tools          | test                   |

Additionally you can utilize some variables to filter which test to run in each task:

Module         | Task                                  | Properties                           | Default
dev/core       | test                                  | | `**/com/google/**/*Test.class`
               |                                       | |
user           | test                                  | gwt.junit.testcase.includes          | `**/*Suite.class`
user           | test.nongwt                           | gwt.nongwt.testcase.includes         | `**/*JreSuite.class`
               |                                       | gwt.nongwt.testcase.excludes         |
user           | test.web.* test.draft.* test.nometa.* | gwt.junit.testcase.web.includes      | `**/*Suite.class`
               |                                       | gwt.junit.testcase.web.excludes      | `**/*JsInteropSuite.class,**/*JreSuite.class,***/OptimizedOnly*`
user           |* test.emma.*                |      | `**/*Suite.class`
               |                                       |      | `**/*JsInteropSuite.class,**/*JreSuite.class,***/OptimizedOnly*`


  • Run all tests in dev

$ ( cd dev && ant test ; cd .. )

_Note: that the last `cd ..' is only needed in Windows._
  • There is another option to do the same but without changing to the module folder. We have to specify the module as the ant task, and the task as a target argument.

$ ant dev -Dtarget=test

  • Run all tests in codeserver

$ ( cd dev/codeserver && ant test )


$ ant codeserver -Dtarget=test

_Note: that we disable dev tests because code server depends on dev
and we don`t want to run its tests._
  • Run all tests in elemental:

$ ( cd elemental && ant test.nongwt )


$ ant elemental -Dtarget=test -Dtest.user.disable=true

_Note: that we have to disable dev and user tests because elemental
depends on both._
  • Run all tests in tools

$ ant tools -Dtarget=test -Dtest.user.disable=true

  • Run only the JsniRefTest in dev

$ ant dev -Dtarget=test \"**/JsniRefTest.class"

  • Run a couple of tests in dev

$ ant dev -Dtarget=test \"**/JsniRefTest.class,**/JsParserTest.class"

Note: that you have to use regular expressions separated by comma to select the test classes to execute.

  • Run all Jre tests in user, they should take not longer than 3min. We have two ways to run them. Although the second case is more complex it is here to know how disable properties work.

$ ( cd user && ant test.nongwt )


$ ant user -Dtarget=test \ \ -Dtest.web.htmlunit.disable=true \ -Dtest.coverage.htmlunit.disable=true \ \ -Dtest.draft.htmlunit.disable=true \ -Dtest.draft.selenium.disable=true \ -Dtest.emma.htmlunit.disable=true \ -Dtest.emma.selenium.disable=true \ -Dtest.nometa.htmlunit.disable=true \ -Dtest.nometa.selenium.disable=true \ -Dtest.web.selenium.disable=true

_Note: that we have to set all disable variables but `test.nongwt.disable`_
  • Run certain Jre tests in the user module.

$ ( cd user && ant test.nongwt -Dgwt.nongwt.testcase.includes="**/I18NJreSuite.class" )

  • Run all GWT tests in user using htmlunit in dev mode.

$ ( cd user && ant )