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7424ee9 Jan 2, 2017
@tschaub @ahocevar @maveric1977 @probins
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Developing

Setting up development environment

You will obviously start by forking the OpenLayers repository.

Travis CI

The Travis CI hook is enabled on the Github repository. This means every pull request is run through a full test suite to ensure it compiles and passes the tests. Failing pull requests will not be merged.

Development dependencies

The minimum requirements are:

  • GNU Make
  • Git
  • Node.js (higher than 0.12.x)
  • Python 2.6 or 2.7
  • Java 7 (JRE and JDK)

The executables git, node, and java should be in your PATH.

You can check your configuration by running:

$ make check-deps

To install the Node.js dependencies run

$ npm install

Working with the build tool

As an OpenLayers developer you will use make to run build targets defined in the Makefile located at the root of the repository. The Makefile includes targets for running the linter, the compiler, the tests, etc.

The usage of make is as follows:

$ make <target>

where <target> is the name of the build target you want to execute. For example:

$ make test

The main build targets are serve, lint, build, test, and check. The latter is a meta-target that basically runs lint, build, and test.

The serve target starts a node-based web server, which we will refer to as the dev server. You'll need to start that server for running the examples and the tests in a browser. More information on that further down.

Other targets include apidoc and ci. The latter is the target used on Travis CI. See OpenLayers's Travis configuration file.

Running the check target

The check target is to be run before pushing code to GitHub and opening pull requests. Branches that don't pass check won't pass the integration tests, and have therefore no chance of being merged into master.

To run the check target:

$ make check

If you want to run the full suite of integration tests, see "Running the integration tests" below.

Running examples

To run the examples you first need to start the dev server:

$ make serve

Then, just point your browser http://localhost:3000/build/examples in your browser. For example http://localhost:3000/build/examples/side-by-side.html.

Run examples against the ol.js standalone build:

The examples can also be run against the ol.js standalone build, just like the examples hosted on GitHub. Start by executing the host-examples build target:

$ make host-examples

After running host-examples you can now open the examples index page in the browser: http://localhost:3000/build/hosted/master/examples/. (This assumes that you still have the dev server running.)

Append ?mode=raw to make the example work in full debug mode. In raw mode the OpenLayers and Closure Library scripts are loaded individually by the Closure Library's base.js script (which the example page loads and executes before any other script).

Running tests

To run the tests in a browser start the dev server (make serve) and open http://localhost:3000/test/index.html in the browser.

To run the tests on the console (headless testing with PhantomJS) use the test target:

$ make test

See also the test-specific README.

Running the integration tests

When you submit a pull request the Travis continuous integration server will run a full suite of tests, including building all versions of the library and checking that all of the examples work. You will receive an email with the results, and the status will be displayed in the pull request.

To run the full suite of integration tests use the ci target:

$ make ci

Running the full suite of integration tests currently takes 5-10 minutes.

This makes sure that your commit won't break the build. It also runs JSDoc3 to make sure that there are no invalid API doc directives.

Adding examples

Adding functionality often implies adding one or several examples. This section provides explanations related to adding examples.

The examples are located in the examples directory. Adding a new example implies creating two or three files in this directory, an .html file, a .js file, and, optionally, a .css file.

You can use simple.js and simple.html as templates for new examples.

Use of the goog namespace in examples

Short story: the OpenLayers examples should not use the goog namespace, except for goog.require.

Longer story: we want that the OpenLayers examples work in multiple modes, with the standalone lib (which has implications of the symbols and properties we export), and compiled together with the OpenLayers library.

Compiling the examples together with the library makes it mandatory to declare dependencies with goog.require statements.