Test all the things over and over.

Usage no npm install needed!

<script type="module">
  import tattoo from '';



Test all the things over and over.


npm install -g tattoo

GitHub token

  1. Generate a GitHub token here:
  2. Put the token in a file called github-token in your working dir


When you run tattoo, it will create and/or reuse a directory called ./tattoo_workspace, relative to the current working dir. This folder is used to clone test target repositories and their dependencies. You can change the directory used with the --workspace-dir or -w option.

Test one repo

tattoo PolymerElements/paper-input

This is the simplest possible case. What actually happens here is that tattoo clones the repository into the local filesystem as ./tattoo_workspace/paper-input, installs all of the dependencies and devDependencies in its bower.json also into ./tattoo_workspace. Then it essentially runs cd ./tattoo_workspace/paper-input && wct --local chrome.

Test two repos

tattoo PolymerElements/paper-input PolymerElements/paper-icon-button

In this case, tattoo clones both repositories into ./tattoo_workspace as paper-input and paper-icon-button, then installs all of their combined dependencies and devDependencies into ./tattoo_workspace. Conflicts in dependencies are currently resolved arbitrarily, but there's an issue (#24) to address that. It then runs wct for both custom element repos.

Test all the paper repos

tattoo PolymerElements/paper-*

Tattoo supports wildcards in repository references so the above actually clones all the PolymerElements repos that start with paper-, installs their dependencies and runs wct for all of the paper element repos.

Test all the paper repos on a specific branch

tattoo "PolymerElements/paper-*#2.0-preview"

In the previous examples, tattoo cloned the requested repositories and simply ran tests on whatever HEAD of their repo is, (typically master branch). It is frequently the case that a specific branch, tag or commit/SHA1 reference is the desired target for test. Tattoo supports this with the #hashref syntax so the above example PolymerElements/paper-*#2.0-preview would tell tattoo to run tests for all the paper- elements which have a branch called 2.0-preview. If the branch name is invalid for a given repo, it should be skipped/excluded.

Test all the repos except that one

tattoo PolymerElements/* -s PolymerElements/style-guide

Test repos with different browser

tattoo PolymerElements/* --wct-flags="--local safari"

Test repos with a config.

Create a tattoo_config.json file to persist a base of options to tattoo. For example:

  "test": [
  "require": [
  "verbose": true,
  "wctflags": ["--local canary", "--color"]

Tattoo will automatically find that file, load its options, and then apply any additional command line arguments. So you could simply run with the config as-is by typing:


Or test the paper-button repo and the paper-hat repo by typing the following, since paper-button is in the config and arguments are additive.

tattoo PolymerElements/paper-hat

Config files support most of the same options as the command-line flags:

  • "test": ["PolymerElements/paper-button#2.0-preview", "PolymerElements/*", etc] Repositories to test.

  • "require": ["PolymerElements/iron-list", "PolymerElements/paper-*", etc] Explicit repos to clone into workspace, but not test. This is useful if you want to force a specific version of a web package that wouldn't be installed by default.

  • "exclude": ["PolymerElements/style-guide", "*/*-deprecated", etc] Repositories not to load. Filters out items from the test and require list.

  • "skip-test": ["PolymerElements/iron-meta", "*/*-alpha", etc] Repositories not to test.

  • "fresh": true|false Clears the workspace for each run, i.e. will clone all repos from remote instead of updating local copies.

  • "github-token": "0123456789ABCDEF1337" Provide a github token via this setting instead of using "github-token" file.

  • "verbose": true|false When true, output all the things.

  • "wct-flags": ["--local chrome"] Set to specify flags passed to wct.

  • "workspace-dir": "/tmp/tattoo-workspace" Specify a different target folder to clone repos and run web-component-tester from.

Clean up installation

rm -rf tattoo_workspace

Or start with a fresh workspace as part of command

tattoo -f

Get help on the cli

tattoo -h

tattoo (test all the things over & over)

  Runs the web-component-tester on custom element git repositories.

  Run test for a specific GitHub repository:
  $ tattoo PolymerElements/paper-button

  Run test for a whole bunch of GitHub repositories:
  $ tattoo PolymerElements/paper-*

  See more examples at


  -t, --test string[]          Repositories to test.  (This is the default
                               option, so the --test/-t switch itself is not
  -s, --skip-test string[]     Repositories not to test.  Overrides the values
                               from the --test
  -r, --require string[]       Explicit repos to load.  Specifying explicit
                               repos will disable running on the default set of
                               repos for the user.
  -e, --exclude string[]       Repositories not to load.  Overrides the values
                               from the --repo and --test flag.
  -f, --fresh                  Set to clone all repos from remote instead of
                               updating local copies.
  -c, --config-file string     Specify path to a json file which contains base
                               configuration values.  Command-line options
                               supercede values in file where they differ.  If
                               file is missing, Tattoo will ignore.
  -C, --color string           Set to "off" if you do not want color in your
                               output.  Defaults to "on".
  -g, --github-token string    Provide github token via command-line flag
                               instead of "github-token" file.
  -v, --verbose                Set to print output from failed tests.
  -w, --wct-flags string[]     Set to specify flags passed to wct.
  -d, --workspace-dir string   Override the default path "tattoo_workspace"
                               where the repositories will be cloned and web-
                               component-tester will run.
  -h, --help                   Print this usage example.
  -V, --version                Print out the version of tattoo.