Making after_commit play nice with use_transactional_fixtures.

spec_helper.rb

# This is an example of how to use database_cleaner gem and
# RSpec tags to make `after_commit` hook play nice with 
# `use_transactional_fixtures`.

# Simply mark the specs that use after_commit with
# `:uses_after_commit` tag.

# ...
require 'database_cleaner'

RSpec.configure do |c|
  # ...

  c.treat_symbols_as_metadata_keys_with_true_values = true
  c.use_transactional_fixtures = true

  # Tag "uses_after_commit" helps when after_commit hook is expected
  # to fire in a spec. It would never fire because of having enabled
  # use_transactional_fixtures. It waits for transaction to end. The
  # workaround disables transaction-wrapping for the tagged spec and
  # instead uses a DatabaseCleaner strategy to wipe the tables here.
  c.around(:each, :uses_after_commit) do |example|
    _orig_use_transactional_fixtures = use_transactional_fixtures
    self.use_transactional_fixtures = false
    DatabaseCleaner.clean_with(:truncation)
    example.call
    DatabaseCleaner.clean_with(:truncation)
    self.use_transactional_fixtures = _orig_use_transactional_fixtures
  end

  # ...
end