State Leakage with sidekiq_job Component Causes Test Failures in RSpec

[kylesnowschwartz]

When using Marginalia with the sidekiq_job component (Marginalia::Comment.components << :sidekiq_job), my test suite encounters state leakage issues. Specifically, RSpec mocks (instance_double or instance_spy) created in one example leak into subsequent examples, causing failures. This problem occurs even when I attempt to disable Marginalia annotations entirely during tests.

The issue appears to be related to how Marginalia interacts with thread-local state or components when constructing SQL comments.

Error:
The following error frequently appears in my test suite:

Failure/Error: DatabaseRewinder.clean unless example.metadata[:skip_db_clean]

#<InstanceDouble(Delayed::Backend::ActiveRecord::Job) (anonymous)> was originally created in one example but has leaked into another example and can no longer be used. rspec-mocks' doubles are designed to only last for one example, and you need to create a new one in each example you wish to use it for.
# ./lib/marginalia/comment.rb:107:in `sidekiq_job'
# ./lib/marginalia/comment.rb:25:in `block in construct_comment'
# ./lib/marginalia/comment.rb:24:in `each'
# ./lib/marginalia/comment.rb:24:in `construct_comment'

Replication Steps:
1. Add Marginalia to the application and enable the sidekiq_job component:

Marginalia::Comment.components << :sidekiq_job

2.	Set up a Sidekiq worker or a test that involves job processing. In tests, use an instance_double to mock the job, such as:

let(:job) do
  instance_double(
    Delayed::Backend::ActiveRecord::Job,
    attributes: { 'id' => 1 }
  )
end

3.	Run an RSpec test that interacts with SQL and Sidekiq, ensuring DatabaseRewinder or a similar cleanup strategy is used in after(:suite) or before(:each) hooks.
4.	Observe the leakage error:

#<InstanceDouble(Delayed::Backend::ActiveRecord::Job)> was originally created in one example but has leaked into another example.

Workarounds Tried:
• Resetting Marginalia::Comment.components in the test environment test.rb:

Marginalia::Comment.components = []

No effect; the error persists.

•	Not adding the `:sidekiq_job` to the list of components:

Tests pass without issues when Marginalia is not present.

Expected Behavior:
Marginalia annotations should not interfere with test isolation or persist any state that causes RSpec mocks to leak between examples.

Actual Behavior:
The use of the sidekiq_job component introduces state leakage that causes test failures. The exact cause appears to be related to Marginalia’s interaction with thread-local or global state during SQL comment construction.

Environment:
• Marginalia version: 1.11.1
• Rails version: 6.1.7.10
• Ruby version: 3.1.6
• Test framework: RSpec (3.13.0)
• Database: MySQL 8.0.36
• Sidekiq version: sidekiq-pro (7.3.2)

Request:
Please investigate how the sidekiq_job component interacts with thread-local or global state. It would be helpful to ensure that Marginalia’s components do not cause interference in test suites or persist state between tests.