Simple and opinionated web testing framework for Selenium WebDriver that follows convention over configuration and integrates with SauceLabs for cross-browser execution in the cloud.
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ChemistryKit 3.10.0 (2013-09-17)

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A simple and opinionated web testing framework for Selenium WebDriver

This framework was designed to help you get started with Selenium WebDriver quickly, to grow as needed, and to avoid common pitfalls by following convention over configuration. To checkout the user group go here. For more usage examples check out our Friends section!

ChemistryKit's inspiration comes from the Saunter Selenium framework which is available in Python and PHP. You can find more about it here.

All the documentation for ChemistryKit can be found in this README, organized as follows:

Getting Started

$ gem install chemistrykit
$ ckit new framework_name

This will create a new folder with the name you provide and it will contain all of the bits you'll need to get started.

$ cd framework_name
$ ckit generate beaker beaker_name

This will generate a beaker file (a.k.a. test script) with the name you provide (e.g. hello_world). Add your Selenium actions and assertions to it.

$ ckit brew

This will run ckit and execute your beakers. By default it will run the tests locally by default. But you can change where the tests run and all other relevant bits in config.yaml file detailed below.

Building a Test Suite

Spec Discovery

ChemistryKit is built on top of RSpec. All specs are in the beaker directory and end in _beaker.rb. Rather than being discovered via class or file name as some systems they are by identified by tag.

it 'with invalid credentials', :depth => 'shallow' do


it 'with invalid credentials', :depth => 'deep' do


All specs should have at least a :depth tag. The depth should either be 'shallow' or 'deep'. Shallow specs are the ones that are the absolute-must-pass ones. And there will only be a few of them typically. Deep ones are everything else.

You can add multiple tags as well.

it 'with invalid credentials', :depth => 'shallow', :authentication => true do


By default ChemistryKit will discover and run the :depth => 'shallow' scripts. To run different ones you use the --tag option.

ckit brew --tag authentication

ckit brew --tag depth:shallow --tag authentication

To exclude a tag, put a ~ in front of it.

ckit brew --tag depth:shallow --tag ~authentication

During development it is often helpful to just run a specific beaker, this can be accomplished with the --beakers flag:

ckit brew --beakers=beakers/wip_beaker.rb

Special Tags

There are some tags that can be used to control various aspects of the harness. The following are supported:

  • public: SOME_VALUE - If you are running your harness against sauce labs, then you can control how the permissions are set for a particular beaker according to the visibility options detailed at the bottom of this page. For example if you wanted a test to be private you could add public: 'private' to your beaker tags.

Formula Loading

Code in the formula directory can be used to build out page objects and helper functions to facilitate your testing. The files are loaded in a particular way:

  • Files in any lib directory are loaded before other directories.
  • Files in child directories are loaded before those in parent directories.
  • Files are loaded in alphabetical order.

So for example if you have a alpha_page.rb file in your formulas directory that depends on a helpers.rb file, then you best put the helpers.rb file in the lib directory so it is loaded before the file that depends on it.

Chemists! The Users of your System Under Test

With ChemistryKit we made it simple to encapsulate data about a particular user that is "using" your application that you are testing. We call them chemists. When you create a new test harness there will be a chemists folder that contains an empty chemists.csv file with only the words key and type at the top. In this folder you can create any number of files with arbitrary user data, just make sure to include the key andtype headings! such as:


An example file might look like this:

admin1,admin,,Mr. Admin,abc123$
normal1,normal,,Ms. Normal,test123%
normal2,normal,,Ms. Normals,test123%

The key should be unique so you can pick a specific user, the type, allows you to group users to aid in their selection ad detailed below.

You can also put a special token in your csv files: {{UUID}} which will be replaced on runtime with a unique identifier. This can be helpful for ensuring certain date is unique across your tests, especially with concurrent runs.

Chemists are made available to your formulas simply by including the ChemistAware module in your formula, and loading the formula with the instance of FormulaLab provided to your beakers:

# my_formula.rb
module Formulas
  class MyFormula < Formula
    include ChemistryKit::Formula::ChemistAware
    if ...

Note that because the Chemist is set after the instantiation of your formula by the FormulaLab you would not be able to do things in the constructor of your formula that depend on a chemist, unless you are explicitly passing in the Chemist. We suggest that you keep the instantiation of your page objects separate from the actions they take.

# my_beaker.rb
describe "my beaker", :depth => 'shallow' do
  let(:my_formula) { @formula_lab.using('my_formula').with('admin1').mix }
  # or
  let(:my_other_formula) { @formula_lab.mix('my_other_formula') }

Here is a summary of the other methods available:

  • .with(key) - Load a specific chemist by the key.
  • .with_random(type) - Load a chemist at random from all those matching type
  • .with_first(type) - Load whatever chemist is first matched by type
  • .and_with(key) - Adds the chemist found by key as a sub-chemist data set to the chemist.

Using .and_with lets you mix up various sets of user data. For example:


Would get you (assuming sub_account1 has a type of sub_account, and a field my_sub_field) the ability to do something like this:


Inside your formula. COOL!

The FormulaLab will handle the heavy lifting of assembling your formula with a driver and correct chemist (if the formula needs one). Also note that the specific instance of chemist is cached so that any changes your formula makes to the chemist is reflected in other formulas that use it.

Catalysts! Driving Tests with Data

In addition to using Chemists to mix data into your test barness, you can also use Catalysts simple key-value stores that can be populated from a CSV file. Formulas can set and get a catalyst or use the catalyize method to directly inject the data into the formula by file name. Once you have a catalyst, simply access the values by their keys:

# my_beaker.rb
describe "my beaker", :depth => 'shallow' do
  let(:my_formula) { @formula_lab.mix('my_other_formula') }

  my_formula.catalyst ='/path/to/data.csv')
  # or 

# my_formula.rb
module Formulas
  class MyFormula < Formula
    some_value = catalyst.my_key

Execution Order

Chemistry Kit executes specs in a random order. This is intentional. Knowing the order a spec will be executed in allows for dependencies between them to creep in. Sometimes unintentionally. By having them go in a random order parallelization becomes a much easier.

Before and After

Chemistry Kit uses the 4-phase model for scripts with a chunk of code that gets run before and after each method. By default, it does nothing more than launch a browser instance that your configuration says you want. If you want to do something more than that, just add it to your spec.

before(:each) do
    # something here

You can even nest them inside different describe/context blocks and they will get executed from the outside-in.

Reporting and CI Integration

Each run of Chemistry Kit saves logging and test output to the evidence directory. And in there will be the full set of JUnit XML files that may be consumed by your CI as well as a final_results.html report file with a full review of all the tests.

Assets generated by Selenium (logs, screenshots, etc.) are stored in a subfolder with a name matching the describe block in your beaker, slugifyed like: my_beaker_name. This is to provide some organization but also allow the integration with jenkins using this plugin.


ChemistryKit is configured by default with a config.yaml file that is created for you when you scaffold out a test harness. Relevant configuration options are detailed below:

Basic Options

  • base_url: The base url of your app, stored to the ENV for access in your beakers and formulas.
  • retries_on_failure: Defaults to 1, set the number of times a test should be retried on failure
  • concurrency: You may override the default concurrency of 1 to run the tests in parallel

  • screenshot_on_fail By default false, set to true to download a screenshot of the failure (supported by sauce labs for now.)

Selenium Connect Options

selenium_connect: Options under this node override the defaults for the Selenium Connect gem. See that documentation for specifics.

Basic Auth Options

basic_auth: Options under this node allow you to configure your test harness to authenticate prior to executing a test. This is helpful for testing against restricted development environments. The options include:

  • username: The username to access your site with basic HTTP authentication.
  • password: The password to access your site with basic HTTP authentication.
  • http_path: An HTTP end-point loaded before each test run to cache the credentials for the test run.
  • https_path: An HTTPS end-point loaded before each test run to cache the credentials for the test run.

Split Testing Options

split_testing: Currently ChemistryKit supports opting out of Optimizely A/B testing. The available options are:

  • provider: Currently only optimizely is supported.
  • opt_out: A value of true will opt you out of the A/B testing

Command Line Usage


Creates a new ChemistryKit project.


ckit new [NAME]


Executes your test cases.


ckit brew [OPTIONS]

Available options for the brew command:

-a, --all                   Run every beaker regardless of tag.
-b, --beakers [BEAKERS]     Pass a list of beaker paths to be executed.
-c, --config [PATH]         Pass the path to an alternative config.yaml file.
--tag [TAGS]                Specify a list of tags to run or exclude.
--params [HASH]             Send a list of "key:value" parameters to the ENV.
-x, --retry [INT]           How many times should a failing test be retried.

generate forumla

Creates a new boilerplate formula object.


ckit generate formula [NAME]

generate beaker

Creates a new boilerplate beaker object.


ckit generate beaker [NAME]


Lists all the tags you have used in your beakers.


ckit tags

Contribution Guidelines

This project conforms to the neverstopbuilding/craftsmanship guidelines. Please see them for details on:

  • Branching theory
  • Documentation expectations
  • Release process

Most importantly, submit your pull requests to the develop branch.

Check out the user group!!forum/chemistrykit-users

It's simple

  1. Create a feature branch from develop: git checkout -b feature/myfeature develop or git flow feature start myfeature
  2. Do something awesome.
  3. Submit a pull request.

All issues and questions related to this project should be logged using the github issues feature.

Install Dependencies

bundle install

Run rake task to test code

rake build

Run the local version of the executable:



The release process is rather automated, just use one rake task with the new version number:

rake release_start['2.1.0']

And another to finish the release:

rake release_finish['A helpful tag message that will be included in the gemspec.']

This handles updating the change log, committing, and tagging the release.


Below you can find some honorable mentions of those friends that are using ChemistryKit:


We are proud that Animoto uses ChemistryKit to help them test their awesome web app.