Quarantine

Quarantine automatically detects flaky tests (i.e. those which fail non-deterministically) and disables them until they're proven reliable.

Quarantine current supports the following testing frameworks. If you need an additional one, please file an issue or open a pull request.

• RSpec

Quarantine should provide the necessary hooks for compatibility with any CI solution. If it's insufficient for yours, please file an issue or open a pull request.

Getting started

Quarantine works in tandem with RSpec::Retry. Add this to your Gemfile and run bundle install:

group :test do
  gem 'quarantine'
  gem 'rspec-retry'
end

In your spec_helper.rb, set up Quarantine and RSpec::Retry. See RSpec::Retry's documentation for details of its configuration.

require 'quarantine'
require 'rspec/retry'

Quarantine::RSpecAdapter.bind

RSpec.configure do |config|
  # Also accepts `:credentials` to override the standard AWS credential chain
  config.quarantine_database = {type: :dynamodb, region: 'us-west-1'}
  # Prevent the list of flaky tests from being polluted by local development and PRs
  config.quarantine_record_tests = ENV["CI"] && ENV["BRANCH"] == "master"

  config.around(:each) do |example|
    example.run_with_retry(retry: 3)
  end
end

Quarantine comes with a CLI tool for setting up the necessary table in DynamoDB, if you use that database.

bundle exec quarantine_dynamodb -h    # See all options

bundle exec quarantine_dynamodb \     # Create the "test_statuses" table in us-west-1 in AWS DynamoDB
  --region us-west-1

How It Works

A flaky test fails on the first run, but passes after being retried via RSpec::Retry.

require "spec_helper"

describe Quarantine do
  it "fails on the first run" do
    raise "error" if RSpec.current_example.attempts == 0
    # otherwise, pass
  end
end

$ CI=1 BRANCH=master bundle exec rspec <filename>
[quarantine] Quarantined tests:
  ./bar_spec.rb[1:1] Quarantine fails on the first run

When the build completes, all test statuses are written to the database. Flaky tests are marked quarantined, and will be executed in future builds, but any failures will be ignored.

A test can be removed from quarantine by updating the database manually (outside this gem), or by configuring quarantine_release_at_consecutive_passes to remove it after it passes on a certain number of builds in a row.

Configuration

In spec_helper.rb, you can set configuration variables by doing:

RSpec.configure do |config|
  config.VAR_NAME = VALUE
end

• quarantine_database: Database configuration (see below), default: { type: :dynamodb, region: 'us-west-1' }
• test_statusus_table: Table name for test statuses, default: "test_statuses"
• skip_quarantined_tests: Skipping quarantined tests during test runs default: true
• quarantine_record_tests: Recording test statuses, default: true
• quarantine_logging: Outputting quarantined gem info, default: true
• quarantine_extra_attributes: Storing custom per-example attributes in the table, default: nil
• quarantine_failsafe_limit: A failsafe limit of quarantined tests in a single run, default: 10
• quarantine_release_at_consecutive_passes: Releasing a test from quarantine after it records enough consecutive passes (nil to disable this feature), default: nil

Databases

Quarantine comes with built-in support for the following database types:

• :dynamodb
• :google_sheets

To use :dynamodb, be sure to add gem 'aws-sdk-dynamodb', '~> 1', group: :test to your Gemfile.

To use :google_sheets, be sure to add gem 'google_drive', '~> 3', group: :test to your Gemfile. Here's an example:

config.quarantine_database = {
  type: :google_sheets,
  authorization: {type: :service_account_key, file: "service_account.json"}, # also accepts `type: :config`
  spreadsheet: {
    type: :by_key, # also accepts `type: :by_title` and `type: :by_url`
    key: "1Jb5fC6wSuIMnP85tUR5knuZ4f5fuu4nMzQF6-0l-EXAMPLE"}, # also accepts `type: :by_title` and `type: :by_url`
}

The spreadsheet first line (1) should contains: id, full_description, updated_at, last_status, location, extra_attributes, consecutive_passes. Something like:

A	B	C	D	E	F	G
id	full_description	updated_at	last_status	location	extra_attributes	consecutive_passes

To use a custom database that's not provided, subclass Quarantine::Databases::Base and pass an instance of your class as the quarantine_database setting:

class MyDatabase < Quarantine::Databases::Base
  ...
end

RSpec.configure do |config|
  config.quarantine_database = MyDatabase.new(...)
end

Extra attributes

Use quarantine_extra_attributes to store custom data with each test in the database, e.g. variables useful for your CI setup.

 config.quarantine_extra_attributes = Proc.new do |example|
   {
     build_url: ENV['BUILDKITE_BUILD_URL'],
     job_id: ENV['BUILDKITE_JOB_ID'],
   }
 end

---

FAQs

Why are quarantined tests not being skipped locally?

Quarantine may be configured to only run in certain environments. Check your spec_helper.rb, and make sure you have all necessary environment variables set, e.g.:

CI=1 BRANCH=master bundle exec rspec

Why is Quarantine failing to connect to DynamoDB?

The AWS client attempts to loads credentials from the following locations, in order:

• The optional credentials field in RSpec.configuration.quarantine_database
• ENV['AWS_ACCESS_KEY_ID'] and ENV['AWS_SECRET_ACCESS_KEY']
• Aws.config[:credentials]
• The shared credentials ini file at ~/.aws/credentials

More detailed information can be found in the AWS SDK documentation

Why is example.clear_exception failing locally?

Example#clear_exception is an attribute added through RSpec::Retry. Make sure it has been installed and configured.