Skip to content
/ clash Public

A diff based testing framework for Jekyll and other static sites.


Notifications You must be signed in to change notification settings


Repository files navigation


Clash is an integration test framework designed for Jekyll developers. It helps you create Jekyll test sites, then build and compare them an expected result.

Build Status Gem Version License


Add this line to your Gemfile:

gem 'clash'

And then execute:

$ bundle

Or install it yourself as:

$ gem install clash


$ clash [dir] [tests] [options]          # Run tests
$ clash list [dir] [tests] [options]     # List tests
$ clash accept [dir] [tests] [options]   # Accept build: overwrite expected files with build files
$ clash new [path] [options]             # Add testing scaffold to or a new test site to [path] (defaults to `./test`)

CLI options for testing

-b, --build             Build mode: Runs only 'before' and 'build' actions
-c, --context NUMBER    On diff errors, show NUMBER of lines of surrounding context (default: 2)
-t, --trace             Display output from system commands in tests
-h, --help              Show help message

The Clash file

A simple clash file with one test might look like this:

  title: Test Build           # Name for your test
  dir: test-site              # Dir containing your Jekyll test site
  build: true                 # Run Jekyll build
  compare: _expected _site    # Compare the contents of _expected/ to _site/

A clash test can be configured with the following options. Each of these is optional.

Option Type Description
title String A descriptive name for the test
dir String Scope tests to this directory.
before String/Array Run system command(s) before running tests.
build Boolean Build the site with Jekyll.
config Hash Configure Jekyll, Octopress Ink plugins. (Info below)
compare String/Array Compare files or directories. Format: "_expected _site"
after String/Array Run system command(s) after running tests.
enforce_missing String/Array Ensure that these files are not found.
trace Boolean Pass through test output to stdout.

Note: Above, String/Array means a configuration can accept either, for example:

compare: _expected _site                     # Compare two directories
compare:                                     # Compare multiple items
  - _expected/index.html _site/index.html
  - _expected/atom.xml _site/atom.xml
  - _expected/posts _site/posts

The order, expected file before site file is important as it affects the readout of the diff when there are failures.


To run only specific tests, pass test numbers separated by commas.

$ clash          # Run all tests.
$ clash 1        # Run only the first test.
$ clash 2,3      # Run the second and third tests.
$ clash 2-4      # Run the second, third, and fourth tests
$ clash :10      # Run the test on line 10
$ clash :10-:35  # Run all tests from line 10 to 35

Typically the clash file is kept in the same directory as the tests. If you are in that directory, you can run $ clash and it will run as usual. If you're not, you'll need to pass the directory to the tests.

$ clash awesome       # Run all tests in the 'awesome' directory, reading awesome/_clash.yml.
$ clash awesome 1     # Run the first test in the 'awesome' directory.

Get Started

Here's how you can get started testing Jekyll plugins with Clash. First generate a testing scaffold.

$ clash new test  # Add a new clash testing scaffold to the `test` directory.

This will generate the following:

  _clash.yml                 # Clash configuration file
  test-site/                 # Directory containing a Jekyll site 
    _config.yml              # Jekyll configuration
      index.html             # File containing expected result
      default.html           # A default layout for your test site
    index.html               # Source file for testing your plugin

And here is what your _clash.yml will look like:

  title: Test Build           # Name for your test
  dir: test-site              # Dir containing your Jekyll test site
  build: true                 # Run Jekyll build
  compare: _expected _site    # Compare the contents of _expected/ to _site/

Next add your plugin to the Jekyll test site and add a sample usage to the index.html file. You can build your site like this:

$ clash --build  # trigger a jekyll build

And once you're ready to go, run your test like this.

$ clash    # run tests

Unless you've already modified your expected files, this will fail, printing a diff of _expected/index.html and the build file _site/index.html. You can accept the build result and copy it over the expected files like this:

$ clash accept   # Copy _site/ files to _expected/

Now when you run $ clash your tests will pass.

This example illustrated a simple test scenario, but Clash can also:

  • Run tasks before and after tests. (Good for setup and cleanup)
  • Test multiple sites.
  • Test the same site multiple times using different Jekyll configurations.
  • Compare single files or entire directories.

Testing multiple use-cases

If you're testing a plugin with multiple use-cases, it's a good idea to create a separate file for each scenario.


Testing multiple sites

If your plugin has a more complex setup, you can create several test sites and test them independently. Your directory structure might look like this:


And your clash file would look like this:

  title: Standard site build
  dir: site-1
  build: true
  compare: _expected _site

  title: Check asset compression
  dir: site-2
  build: true
  compare: _expected _site

Other than the title, The difference between these two tests is the dir config, which changes the test directory for Clash.

Test a site with multiple configurations.

Sometimes the only difference between your test scenarios is the site configuration. Rather than create two separate sites, Clash can run tests against a single site, using different configurations for each build.

Here's how you'd set up your test site:

    _expected/   # Each cofiguration's comparison files are in nested subdirectories

Because you'll be comparing multiple builds of the same site, instead of keeping comparison files directly under the _expected directory, it's a good idea to group them in subdirectories underneath _expected/.

Here's how your clash file might look:

  title: Standard build            # Reads _config.yml file as usual
  dir: site
  build: true
  compare: _expected/default _site

  Title: Alternate Configuration A
  build: true
  dir: site
    jekyll: _config_a.yml          # Build with _config_a.yml
  compare: _expected/config_a _site
  Title: Alternate Configuration B
  build: true
  dir: site
    jekyll: _config_b.yml          # Build with _config_b.yml
  compare: _expected/config_b _site

When Clash builds your site with a custom configuration, it uses the command jekyll build --config _config_a.yml. You can even use multiple configurations like this.

    - _config.yml
    - _config_a.yml

Here _config_a.yml will override settings in _config.yml when the site is built.

Test Octopress Ink plugin configurations

If you are developing an Octopress Ink plugin with the slug awesome-sauce you can configure it by by using the config hash. Here's an example:

  awesome-sauce: _awesome-sauce.yml  # any file name works

This will copy site/_awesome-sauce.yml to your plugin's configuration path at site/_plugins/awesome-sauce/config.yml. If there is already a configuration file in that location, it will be backed up and then restored after tests.


If you find yourself adding repetitive before or after commands, you can create a task to reference these commands for reuse in other tests. Here's an example clash config file.

      - rm -rf _site
      - rm -rf .gist-cache
      - echo "Gist cache removed"
  title: Test build
  before: remove_caches
  build: true
    - reset_site
    - echo "Gist build complete"

Notice the first test isn't a test at all. It's a hash of tasks, each with its own defined command(s). The test below calls tasks in its before and after blocks. Note that tasks can be used along with any other system command in before or after blocks.


  1. Fork it ( )
  2. Create your feature branch (git checkout -b my-new-feature)
  3. Commit your changes (git commit -am 'Add some feature')
  4. Push to the branch (git push origin my-new-feature)
  5. Create a new Pull Request


A diff based testing framework for Jekyll and other static sites.







No packages published