tree: 62f77e468e4f7acc228fa4ab877fb2f9be617546 [path history] [tgz]
  1. app/
  2. edit-walkthrough/
  3. .gitattributes
  4. .gitignore
  5. BUILD
  9. server.go
  10. wct.conf.js

Gerrit Polymer Frontend

Follow the setup instructions for Gerrit backend developers where applicable.

Installing Bazel

Follow the instructions here to get and install Bazel.

Installing Node.js and npm packages

The minimum nodejs version supported is 8.x+

# Debian experimental
sudo apt-get install nodejs-legacy
sudo apt-get install npm

# OS X with Homebrew
brew install node
brew install npm

All other platforms: download from

Various steps below require installing additional npm packages. The full list of dependencies can be installed with:

npm install

It may complain about a missing typescript@2.3.4 peer dependency, which is harmless.

Running locally against production data

Go server

To test the local Polymer frontend against simply execute:


Then visit http://localhost:8081

This method is based on a simple hand-written Go webserver. Mostly it just switches between serving files locally and proxying the real server based on the file name. It also does some basic response rewriting, e.g. it patches the config/server/info response with plugin information provided on the command line:

./polygerrit-ui/ --plugins=plugins/my_plugin/static/my_plugin.js,plugins/my_plugin/static/my_plugin.html

The biggest draw back of this method is that you cannot log in, so cannot test scenarios that require it.

MITM Proxy

MITM Proxy is an open source product for proxying https servers. The contrib/mitm-ui/ directory contains scripts (and documentation) for using this technology (instead of the Go server). These scripts are somewhat experimental and unmaintained though.

Running locally against a Gerrit test site

Set up a local test site once:

  1. Build Gerrit
  2. Set up a local test site.
  3. Optionally populate your test site with some test data.

For running a locally built Gerrit war against your test instance use this command, and add the --polygerrit-dev option, if you want to serve the Polymer frontend directly from the sources in polygerrit_ui/app/ instead of from the war:

$(bazel info output_base)/external/local_jdk/bin/java \
    -DsourceRoot=$(bazel info workspace) \
    -jar bazel-bin/gerrit.war daemon \
    -d $GERRIT_SITE \
    --console-log \

Running Tests

This step requires the web-component-tester npm module.

Note: it may be necessary to add the options --unsafe-perm=true --allow-root to the npm install command to avoid file permission errors.

For daily development you typically only want to run and debug individual tests. Run the local Go proxy server and navigate for example to http://localhost:8081/elements/shared/gr-account-entry/gr-account-entry_test.html. Check “Disable cache” in the “Network” tab of Chrome's dev tools, so code changes are picked up on “reload”.

Our CI integration ensures that all tests are run when you upload a change to Gerrit, but you can also run all tests locally in headless mode:

npm test

To allow the tests to run in Safari:

  • In the Advanced preferences tab, check “Show Develop menu in menu bar”.
  • In the Develop menu, enable the “Allow Remote Automation” option.

To run Chrome tests in headless mode:

WCT_HEADLESS_MODE=1 WCT_ARGS='--verbose -l chrome' ./polygerrit-ui/app/

Style guide

We follow the Google JavaScript Style Guide with a few exceptions. When in doubt, remain consistent with the code around you.

In addition, we encourage the use of ESLint. It is available as a command line utility, as well as a plugin for most editors and IDEs.

eslint-config-google is a port of the Google JS Style Guide to an ESLint config module, and eslint-plugin-html allows ESLint to lint scripts inside HTML. We have an .eslintrc.json config file in the polygerrit-ui/ directory configured to enforce the preferred style of the PolyGerrit project. After installing, you can use eslint on any new file you create. In addition, you can supply the --fix flag to apply some suggested fixes for simple style issues. If you modify JS inside of <script> tags, like for test suites, you may have to supply the --ext .html flag.

Some useful commands:

  • To run ESLint on the whole app, less some dependency code:
npm run eslint
  • To run ESLint on just the subdirectory you modified:
node_modules/eslint/bin/eslint.js --ext .html,.js polygerrit-ui/app/$YOUR_DIR_HERE
  • To run the linter on all of your local changes:
git diff --name-only master | xargs node_modules/eslint/bin/eslint.js --ext .html,.js

We also use the polylint tool to lint use of Polymer. To install polylint, execute the following command.

To run polylint, execute the following command.

bazel test //polygerrit-ui/app:polylint_test


npm run polylint

Template Type Safety

Polymer elements are not type checked against the element definition, making it trivial to break the display when refactoring or moving code. We now run additional tests to help ensure that template types are checked.

A few notes to ensure that these tests pass

  • Any functions with optional parameters will need closure annotations.
  • Any Polymer parameters that are nullable or can be multiple types (other than the one explicitly delared) will need type annotations.

These tests require the typescript and fried-twinkie npm packages.

To run on all files, execute the following command:



npm run test-template

To run on a specific top level directory (ex: change-list)

TEMPLATE_NO_DEFAULT=true ./polygerrit-ui/app/ //polygerrit-ui/app:template_test_change-list

To run on a specific file (ex: gr-change-list-view), execute the following command:

TEMPLATE_NO_DEFAULT=true ./polygerrit-ui/app/ //polygerrit-ui/app:template_test_<TOP_LEVEL_DIRECTORY> --test_arg=<VIEW_NAME>
TEMPLATE_NO_DEFAULT=true ./polygerrit-ui/app/ //polygerrit-ui/app:template_test_change-list --test_arg=gr-change-list-view