Te Aro ActiveRecordObserver

Designed to help with understanding how a particular block of code changes your ActiveRecord objects. See what gets changed, what type of objects are created, and what the values on those objects are. It can also display the sequence of callbacks that was triggered.

Installation

Add this line to your application's Gemfile:

gem 'te_aro'

And then execute:

$ bundle

Or install it yourself as:

$ gem install te_aro

Usage

# With defaults:
TeAro::Observer.new.observe { @some_ar_object.do_something_that_triggers_callbacks }

# With the tracer enabled (slow):
TeAro::Observer.new(:tracer => true).observe { @some_ar_object.do_something_that_triggers_callbacks }

# Can also use the Kernel#aro method to call with defaults:
aro { @some_ar_object.do_something }

Sample Session

Te Aro in action on gitlab code:

# gitlab-development-kit/gitlab/spec/services/merge_requests/create_service_spec.rb
      # ...
      before do
        project.team << [user, :master]
        project.team << [assignee, :developer]
        allow(service).to receive(:execute_hooks)

        aro { @merge_request = service.execute }
      end
      # ...

Run:

$ bundle exec rspec spec/services/merge_requests/create_service_spec.rb -fd

Output in log/te_aro.log:

Object Count Changes:
        GitlabIssueTrackerService: +1
        MergeRequest: +1
        MergeRequestDiff: +1
New ActiveRecord objects:
        GitlabIssueTrackerService (id=1)
                id: 1
                type: GitlabIssueTrackerService
                project_id: 1
                created_at: 2016-03-21 07:17:46 UTC
                updated_at: 2016-03-21 07:17:46 UTC
                active: false
                properties: {}
                template: false
                push_events: true
                issues_events: true
                merge_requests_events: true
                tag_push_events: true
                note_events: true
                build_events: true
                category: issue_tracker
                default: true
        MergeRequest (id=1)
                id: 1
                target_branch: master
                source_branch: feature
                source_project_id: 1
                author_id: 3
                title: Awesome merge_request
                created_at: 2016-03-21 07:17:46 UTC
                updated_at: 2016-03-21 07:17:46 UTC
                state: opened
                merge_status: unchecked
                target_project_id: 1
                iid: 1
                description: please fix
                position: 0
                merge_params: {}
                merge_when_build_succeeds: false
        MergeRequestDiff (id=1)
                id: 1
                state: collected
                st_commits: [{:id=>"0b4bc9a49b562e85de7cc9e834518ea6828729b9", :message=>"Feature added\n\nSigned-off-by: Dmitriy Zaporozhets <[email protected]>\n", :parent_ids=>["ae73cb07c9eeaf35924a10f713b364d32b2dd34f"], :authored_date=>2014-02-27 21:26:01 +1300, :author_name=>"Dmitriy Zaporozhets", :author_email=>"[email protected]", :committed_date=>2014-02-27 21:26:01 +1300, :committer_name=>"Dmitriy Zaporozhets", :committer_email=>"[email protected]"}]
                st_diffs: [{:diff=>"--- /dev/null\n+++ b/files/ruby/feature.rb\n@@ -0,0 +1,5 @@\n+class Feature\n+  def foo\n+    puts 'bar'\n+  end\n+end\n", :new_path=>"files/ruby/feature.rb", :old_path=>"files/ruby/feature.rb", :a_mode=>"0", :b_mode=>"100644", :new_file=>true, :renamed_file=>false, :deleted_file=>false, :too_large=>false}]
                merge_request_id: 1
                created_at: 2016-03-21 07:17:46 UTC
                updated_at: 2016-03-21 07:17:46 UTC
                base_commit_sha: ae73cb07c9eeaf35924a10f713b364d32b2dd34f
                real_size: 1
Changed and persisted ActiveRecord objects:
        Project (id=1)
                last_activity_at: 2016-03-21 07:17:45 UTC -> 2016-03-21 07:17:46 UTC

Output

By default, output is logged to log/te_aro.log. This can be changed by passing a Logger instance when constructing the observer.

Eg to log to STDOUT:

TeAro::Observer.new(:logger => Logger.new(STDOUT)).observe { some_ar_object.do_something }

Options

Options are passed as a hash to Observer.new.

The following options are available:

• :tracer Show the ActiveRecord callbacks that were called. A truthy value will turn this on, it is off by default
• :tracker Show ActiveRecord objects that have been created or changed. A falsey value will turn this off. On by default.
• :logger Sets the logger used to record output.

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/powershop/te_aro.

License

The gem is available as open source under the terms of the MIT License.