with_clues - temporarily provide more context when tests fail. Beats puts

Suppose you have this:

expect(page).to have_content("My Awesome Site")

And Capybara says that that content is not there and that is all it says. You might slap in a puts page.html and try again. Instead, what if you could not do that and do this?

with_clues do
  expect(page).to have_content("My Awesome Site")
end

And that would print out your HTML? Or your JavaScript console? Or whatever else? Neat, right?

Install

gem install with_clues

Or, in Gemfile:

gem "with_clues"

For Rails, you might want to do this:

gem "with_clues", group: :test

Then bundle install

Setup

Best thing to do is mix into your base test class.

For Minitest

If you are using Rails, probably something like this:

# test/test_helper.rb
require "with_clues"

class ActiveSupport::TestCase
  include WithClues::Method

  # ...
end

If you aren't using Rails, add the require and include wherever you configure your base test case (or just put it in each test individually).

For RSpec

You'll want to put this in your spec/spec_helper.rb file:

require "with_clues"
RSpec.configure do |c|
  c.include WithClues::Method
end

Use

In general, you would not want to wrap all tests with with_clues. This is a diagnostic tool to allow you to get more information on a test that is failing. As such, your workflow might be:

1. Notice a test failing that you cannot easily diagnose

2. Wrap the failing assertion in with_clues:

   with_clues do
     expect(page).to have_selector("div.foo.bar")
   end

3. Run the test again, and see the additional info.

4. Once you've made the test pass, remove with_clues

Included Clues

There are three clues included:

• Dumping HTML - when page exists, it will dump the contents of page.html when the test fails

• Dumping Browser logs - for a browser-based test, it will dump anything that was console.log'ed

• Arbitrary context you pass in, for example when testing an Active Record

  person = Person.where(name: "Pat")
  with_clues(person.inspect) do
    expect(person.valid?).to eq(true)
  end

  If the test fails, person.inspect is included in the output

Adding Your Own Clues

with_clues is intended as a diagnostic tool you can develop and enhance over time. As your team writes more code or develops more conventions, you can develop diagnostics as well.

To add one, create a class that implements dump(notifier, context:):

• notifier is a WithClues::Notifier that you should use to produce output:
  • notify - output text, preceded with [ with_clues ] (this is so you can tell output from your code vs from with_clues)
  • blank_line - a blank line (no prefix)
  • notify_raw - output text without a prefix, useful for removing ambiguity about what is being output
• context: the context passed into with_clues (nil if it was omitted)

For example, suppose you want to output information about an Active Record like so:

with_clues(person) do
  # some test
end

If this test fails, you output the person's ID and any errors.

Create this class, e.g. in spec/support/active_record_clues.rb:

class ActiveRecordClues
  def dump(notifier, context:)
    if context.kind_of?(ActiveRecord::Base)
      notifier.notify "#{context.class}: id: #{context.id}"
      notifier.notify "#{context.class}: errors: #{context.errors.inspect}"
    end
  end
end

To use it, call WithClues::Method.use_custom_clue, for example, in your spec_helper.rb:

require "with_clues"
require_relative "support/active_record_clues"

RSpec.configure do |c|
  c.include WithClues::Method
end

WithClues::Method.use_custom_clue ActiveRecordClues

You can use multiple clues by repeatedly calling use_custom_clue

Developing

• Get set up with bin/setup
• Run tests with bin/ci