Configure database_cleaner for a test suite that contains Capybara js specs.

spec_helper.rb

RSpec.configure do |config|
  config.use_transactional_fixtures = false

  config.before(:suite) do
    DatabaseCleaner.clean_with :truncation
  end

  config.before(:each) do
    if example.metadata[:js]
      DatabaseCleaner.strategy = :truncation
    else
      DatabaseCleaner.strategy = :transaction
    end
    DatabaseCleaner.start
  end

  config.after(:each) do
    DatabaseCleaner.clean
  end
end

Note: example.metadata is no longer available in the config.before(:each) block from at least 3.2.0. See: https://github.com/rspec/rspec-core/blob/13c6674f8021ab7f00dc70559871169d2595cc12/Changelog.md The error message describes this best:

*** RSpec::Core::ExampleGroup::WrongScopeError Exception: `metadata` is not available from within an example (e.g. an `it` block) or from constructs that run in the scope of an example (e.g. `before`, `let`, etc). It is only available on an example group (e.g. a `describe` or `context` block).

One can get around this by using config.before(:each) do |example|