angular-cn/aio/tools/examples

Overview

Many of the documentation pages contain snippets of code examples. Extract these snippets from real working example applications, which are stored in subfolders of the /aio/content/examples folder. Each example can be built and run independently. Each example also provides e2e specs, which are run as part of our CircleCI legacy build tasks, to verify that the examples continue to work as expected, as changes are made to the core Angular libraries.

In order to build, run and test these examples independently you need to install dependencies into their sub-folder. Also there are a number of common boilerplate files that are needed to configure each example's project. Maintain these common boilerplate files centrally to reduce the amount of effort if one of them needs to change.

Boilerplate overview

As mentioned, many of the documentation pages contain snippets extracted from real example applications. To achieve that, all those applications needs to contain a basic boilerplate. E.g. a node_modules folder, package.json with scripts, etc.

No one wants to maintain the boilerplate on each example, so the goal of this tool is to provide a set of files that works across all the examples.

Boilerplate files

Inside /aio/tools/examples/shared/boilerplate you will find a set of folders representing each project type.

Currently you will find the next project types:

• cli - For CLI based examples. This is the default one, to be used in the majority of the examples.
• getting-started - CLI-based with its own set of styles.
• i18n - CLI-based with additional scripts for internationalization.
• ivy - CLI-based with additional configuration for running the examples with the Ivy renderer and ngstc compiler.
• schematics - CLI-based with additional scripts for building schematics.
• service-worker - CLI-based with additional packages and configuration for service workers.
• systemjs - Currently in deprecation, only used in a few examples.
• testing - CLI-based with additional styles for jasmine testing.
• universal - CLI-based with an extra server target.

There is also a common folder that contains files used in all different examples.

The example-config.json

Each example is identified by an example-config.json configuration file in its root folder. This configuration file indicates what type of boilerplate this example needs. E.g.

{
  "projectType": "cli",
  "useCommonBoilerplate": true
}

If the file is empty then the default type of cli is assumed. When the boilerplate tooling runs, it will copy into the example folder all of the appropriate files based on the project type.

A node_modules to share

With all the boilerplate files in place, the only missing piece are the installed packages. For that you have a /aio/tools/examples/shared/package.json which contains all the packages needed to run all the examples through all different boilerplates.

After installing these dependencies, a node_modules will be created at /aio/tools/examples/shared/node_modules. This folder will be symlinked into each example. So it is not a copy like the other boilerplate files. This solution works in all OSes. Windows may require admin rights.

End to end tests

End to end changes between boilerplates.

For CLI applications, create a app.e2e-spec.ts inside the e2e folder. The tooling will run ng e2e for each CLI based examples.

For SystemJS, each example contains an e2e-spec.ts file. You can find all the related configuration files in the /aio/tools/examples/shared folder.

example-boilerplate.js

This script installs all the dependencies that are shared among all the examples, creates the node_modules symlinks and copy all the boilerplate files where needed. It won't do anything about stackblitz nor e2e tests.

It also contains a function to remove all the boilerplate. It uses a git clean -xdf to do the job. It will remove all files that don't exist in the git repository, including any new file that you are working on that hasn't been stage yet. So be sure to save your work before removing the boilerplate.

run-example-e2e.js

This script will find all the e2e-spec.ts files and run them.

To not run all tests, you can use the --filter=name flag to run the example's e2e that contains that name.

It also has an optional --setup flag to run the example-boilerplate.js script and install the latest webdriver.

It will create a /aio/protractor-results.txt file when it finishes running tests.

Updating example dependencies

With every major release, we update the examples to be on the latest version. The following steps to update are:

• In the shared/package.json file, bump all the @angular/*, @angular-devkit/*, rxjs, typescript, and zone.js package versions to the version that corresponds with the framework version.
• In the shared folder, run yarn to update the dependencies for the shared node_modules and the yarn.lock file.
• In the boilerplate folder, go through each sub-folder and update the package.json dependencies if one is present.
• Follow the update guide to update the common files used in the examples based on project type.