Ruby on Rails Research & Evidence-Based Practice 4

Question 1

Which Rails testing approach provides the most evidence that a refactored method maintains correct behavior?

Accepted Answer

Regression tests written before refactoring

Answer

Writing regression tests before refactoring captures the existing behavior as a specification, providing evidence the refactor is safe.

Question 2

In evidence-based Rails development, what is the primary purpose of tracking `db_runtime` and `view_runtime` in production logs?

Accepted Answer

To identify whether bottlenecks are in the database or view rendering layer

Answer

Rails logs `db_runtime` (SQL time) and `view_runtime` (template rendering time) separately, allowing developers to pinpoint which layer is slow.

Question 3

Which method of ActiveRecord::Calculations provides aggregate evidence about data distributions useful for optimizing scopes?

Accepted Answer

relation.group(:column).count

Answer

`group(:column).count` returns a hash of value frequencies, revealing data distributions to inform index and scope decisions.

Question 4

A developer uses `rails stats` to gather evidence about codebase growth. What does a declining `Code to Test ratio` indicate?

Accepted Answer

Test coverage is growing relative to application code

Answer

A lower or declining code-to-test ratio means more test code relative to application code, indicating improved test coverage.

Question 5

To collect evidence that a Rails background job completes within an SLA, which Sidekiq feature provides job timing data?

Accepted Answer

Sidekiq::Stats

Answer

`Sidekiq::Stats` provides aggregate metrics including processed count, failed count, and queue latency for SLA monitoring.

Ruby on Rails Practice Test