Test Tube

A test tube to conduct software experiments 🧪

Installation

Add this line to your application's Gemfile:

gem "test_tube"

And then execute:

bundle install

Or install it yourself as:

gem install test_tube

Usage

To make TestTube available:

require "test_tube"

Assuming we'd like to experiment on the answer to the Ultimate Question of Life, the Universe, and Everything with the following matcher:

class BeTheAnswer
  def matches?
    42.equal?(yield)
  end
end

One possibility would be to invoke a whole block of code:

block_of_code = -> { "101010".to_i(2) }

experiment = TestTube.invoke(matcher: BeTheAnswer.new, negate: false, &block_of_code)
# => <TestTube actual=42 error=nil got=true>

experiment.actual # => 42
experiment.error  # => nil
experiment.got    # => true

An alternative would be to pass directly the actual value as a parameter:

actual_value = "101010".to_i(2)

experiment = TestTube.pass(actual_value, matcher: BeTheAnswer.new, negate: false)
# => <TestTube actual=42 error=nil got=true>

experiment.actual # => 42
experiment.error  # => nil
experiment.got    # => true

Matchi matchers

To facilitate the addition of matchers, a collection is available via the Matchi project.

Let's use a built-in Matchi matcher:

gem install matchi

require "matchi"

An example of successful experience:

experiment = TestTube.invoke(
  matcher: Matchi::RaiseException.new(:NoMethodError),
  negate:  false
) { "foo".blank? }
# => <TestTube actual=#<NoMethodError: undefined method `blank?' for "foo":String> error=nil got=true>

experiment.actual # => #<NoMethodError: undefined method `blank?' for "foo":String>
experiment.error  # => nil
experiment.got    # => true

Another example of an experiment that fails:

experiment = TestTube.invoke(
  matcher: Matchi::Be.new(0.3),
  negate:  false,
  &-> { 0.1 + 0.2 }
) # => <TestTube actual=0.30000000000000004 error=nil got=false>

experiment.actual # => 0.30000000000000004
experiment.error  # => nil
experiment.got    # => false

Finally, an experiment which causes an error:

experiment = TestTube.invoke(
  matcher: Matchi::Match.new(/^foo$/),
  negate:  false
) { BOOM }
# => <TestTube actual=nil error=#<NameError: uninitialized constant BOOM> got=nil>

experiment.actual # => nil
experiment.error  # => #<NameError: uninitialized constant BOOM>
experiment.got    # => nil

Contact

• Source code: https://github.com/fixrb/test_tube
• Chinese blog post: https://ruby-china.org/topics/41390
• Japanese blog post: https://qiita.com/cyril/items/36174b619ff1852c80ec

Versioning

Test Tube follows Semantic Versioning 2.0.

License

The gem is available as open source under the terms of the MIT License.

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This project is sponsored by: