TestProf II: Factory therapy for your Ruby tests—Martian Chronicles, Evil Martians’ team blog

Some key highlights and points from the linked article TestProf II: Factory therapy for your Ruby tests Show archive.org snapshot .

The Problem with Factories in Ruby Tests

• Factories are used to easily generate test data.
• However, they can unintentionally slow down test suites by creating unnecessary or excessive associated data (factory cascades).

Understanding Factory-Induced Slowdowns

• Factories often create additional data (e.g., associated records) that can significantly slow down tests, in the worst cases accounting for up to ~85% of testing time.
• This slowdown can go unnoticed until it severely impacts overall test performance.

Solution: TestProf Tools

• TestProf Show archive.org snapshot is a suite of tools designed to improve the performance of Ruby test suites.
• Key tools include:
  • EventProf: Measures the time spent on specific events during tests to identify slow processes.
  • FactoryProf: Tracks and analyzes factory usage to pinpoint inefficiencies such as:
    • Overused factories being invoked repeatedly in tests.
    • Factories with excessive cascading associations causing unnecessary data generation.
    • Identification of the most time-consuming factories and their locations in the codebase.
  • Insights are provided in the form of reports and visual tools, such as flamegraphs, which highlight bottlenecks in factory usage and indicate areas needing optimization.

How TestProf Helps

• Identifies overused factories or those causing cascading data creation and even displays helpful flamegraphs for better visualization.
• Provides actionable insights like:
  • Number of factory calls in each test and the time spent on each.
  • Breakdown of associated records created unintentionally by factories.
  • Visualization of hotspots in the test suite using flamegraphs.

Suggested Solutions

• Explicit Associations: Pass only the required data to a factory to minimize unnecessary records.
• Association Inference: Infer associations from already-created records to avoid redundant data generation.
• FactoryDefault: Reuse records inside a factory implicitly as a default to streamline test data.
• AnyFixture: Define commonly used records upfront as fixtures for use across tests.