confidence_check - Get confidence in your test setup

Sometimes tests have some setup required before you run the test, and sometimes that setup is complicated, and sometimes that setup can break if other parts of the system aren't working. When that happens, you can a test failure that doesn't mean your code is broken, just that some other code is broken.

visit "/"
click_on "sign_up"

fill_in :username, with: "davetron5000"
expect {
  click_on "Create an Account"
}.to change {
  Account.count
}.by(1)

What if the sign_up link is broken, but your account registration code is working perfectly? You'll get a test failure on that call to fill_in. This is confusing.

confidence_check do
  visit "/"
  click_on "sign_up"
end

fill_in :username, with: "davetron5000"
expect {
  click_on "Create an Account"
}.to change {
  Account.count
}.by(1)

Now, if something goes wrong getting to the page, i.e. setting up for your test, you'll get a different error: CONFIDENCE CHECK FAILED.

This can help tremendously with isolating the root cause of a test failure. Instead of digging into the code you are testing, you can quickly see that some other code that is needed just to run a test is broken.

Install

> gem install confidence-check

Or, if using a Gemfile:

gem "confidence-check"

Setup - RSpec

1. Include ConfidenceCheck::ForRSpec in your test. The most common way is in your spec_helper.rb:

   RSpec.configure do |c|
     c.include ConfidenceCheck::ForRSpec
   end

2. You can now call confidence_check anywhere you need to assert your test is set up:

   RSpec.describe Person do
     include ConfidenceCheck
     describe "#age" do
       it "is based on birthdate" do
         person = create(:person)
   
         confidence_check do
           expect(person.birthdate).not_to be_nil
         end
   
         expect(person.age).to eq(47)
       end
     end
   end

Setup - Minitest

1. Include ConfidenceCheck::ForMinitest in your test. For Rails, you'd include this in ActiveSupport::TestCase:

   # test/test_helper.rb
   
   class ActiveSupport::TestCase
     include ConfidenceCheck::ForMinitest
   
     # ...
   end

2. You can now call confidence_check anywhere you need to assert your test is set up:

   class PersonTest < MiniTest::Test
     include ConfidenceCheck
     def test_age
       person = create(:person)
   
       confidence_check do
         refute_nil person.birthdate
       end
   
       assert_equal 47,person.age
     end
   end

Setup - Custom

1. The module ConfidenceCheck::CheckMethod makes a call to exception_klasses, which returns an array of exception classes you want to rescue inside a confidence_check call. You'll need to implement this yourself:

   module MyCustomConfidenceCheck
     include ConfidenceCheck::CheckMethod
     def exception_klasses
       [ MyCustomError ]
     end
   end

2. Note that you can include any of the other modules as a base. For example, if you want to use RSpec but add your own additional method:

   module MyCustomConfidenceCheck
     include ConfidenceCheck::ForRSpec
     include ConfidenceCheck::CheckMethod
     def exception_klasses
       super + [ MyCustomError ]
     end
   end

3. Now, you need to include this module in your tests. HOw to do this dependson how you are writing tests, but hopefully it's as simple as include MyCustomConfidenceCheck

Setup - with Capybara

Capybara raises several exceptions if navigation or page manipulation fails. These are almost always the types of failures a confidence check should notify you about because they usually mean a page or pages aren't even working enough for you to execute a test.

If you use the *WithCapybara versions of the modules, you can wrap your Capybara navigation commands in a confidence_check:

RSpec

RSpec.configure do |c|
  c.include ConfidenceCheck::ForRSpec::WithCapybara
end

Minitest

# test/test_helper.rb

class ActiveSupport::TestCase
  include ConfidenceCheck::ForMinitest::WithCapybara

  # ...
end

Custom

module MyCustomConfidenceCheck
  include ConfidenceCheck::CheckMethod
  def exception_klasses
    [ MyCustomError, Capybara::CapybaraError ]
  end
end

# OR, to e.g. re-use RSpec's

module MyCustomConfidenceCheck
  include ConfidenceCheck::ForRSpec::WithCapybara
  include ConfidenceCheck::CheckMethod
  def exception_klasses
    super + [ MyCustomError ]
  end
end

Developing

• Set up with bin/setup
• Run tests with bin/rspec or bin/rake