CI Gates, Test Result Caches, and the Code Graph That Might Tell Us What to Test
What I learned from splitting Rails CI by risk, caching exact test results, and exploring whether AI and code graphs can make test selection safer.
Tag: testing
When Ubuntu Builds Fail on libvips but macOS Does Not
Why a Rails test suite can fail on Ubuntu because of an older native libvips, and how to upgrade it safely without confusing it with the ruby-vips gem.
The CI failures that moved every time you reran them
How a moving set of Rails CI flakes exposed shared download state, Selenium stale-node retries, and specs asserting before the browser settled.
The Hard Part of AI PR Review Is Not Reading the Diff
A practical look at Alibaba OpenCodeReview, why diff-only AI review is not enough, and how to use AI reviewers without trusting them too much.
Deterministic Rails CI failures: read the evidence first
A Rails CI debugging story: following the evidence to shared test state, instead of weakening assertions to make failures disappear.
Rails UJS to Turbo: the event timing bug CI didn't catch
Migrating Rails UJS to Turbo can silently break submit buttons and resets in production, because Turbo's event timing and Promise handling differ from UJS.
Tiny Puzzles for Testing and Debugging AI Agents
Small probe tasks for testing local AI agents: function calling, skill awareness, prompt-length pressure, cache behavior, and layer-by-layer debugging.
The Ghost in the Test Suite: Fixing Rails Database Cleanup
A flaky RSpec suite traced to a Rake task that commits data outside the per-test transaction, and how DatabaseCleaner's truncation strategy fixes it.
Why Using Business Logic for Test Setup Is a Rails Antipattern
Using application services to build test data couples your specs to that business logic, making test suites slow and fragile; Factory Bot traits fix it.
Ruby Debugging in VS Code: Shopify LSP, rdbg, and RSpec
How to wire up VS Code for Ruby debugging with the Shopify Liquid LSP, the rdbg debugger from Ruby's debug gem, and launch configs for RSpec, Minitest, and Cucumber.
Active Storage Variants: Multiple Sizes and Testing Pitfalls
Active Storage's variant API gets rough past the basic thumbnail case: multiple sizes, per-attachment metadata, and tests that break on file-not-found errors.
When to Mock and When to Hit the Real Thing in Rails Tests
A practical breakdown of when to mock external dependencies in Rails tests versus using the real thing, built around the test pyramid, VCR, WebMock, and Pact.
How Rails Sessions Work with Warden and Cookies
Rails keeps users logged in by encrypting the whole session into a browser cookie, then lets Warden authenticate each request, which changes how you should test it.
Is Your Endpoint I/O Bound or CPU Bound?
How to tell whether a slow endpoint is I/O bound or CPU bound, using system monitors, timing, and cProfile, and why the fix differs for each.
Debugging Exceptions: Break on Throw, Not Catch-All
Catch-all exception handlers hide the real bug. Debuggers that pause on every thrown exception, caught or not, find it faster than logging ever will.
Timezone Bugs in Ruby: BST vs UTC in CI and Cron
How British Summer Time breaks Ruby tests, cron schedules, and cloud functions that assume UTC, and how to write timezone-aware specs instead.
Code Review Anti-Patterns That Waste the Most Time
The code review anti-patterns that slow teams down most: giant PRs, style-war comments, and reviews that skip the business context entirely.
Debugging Transaction Deadlocks in Rails Tests: A Case Study
A Rails test suite hung intermittently until transactional tests, ActiveJob, and ActiveStorage turned out to be racing over the same locked rows.
Monkey-Patching in PHP vs Ruby: Why One Is an Anti-Pattern
Runtime method overrides work very differently in PHP and Ruby: one has no rollback mechanism, the other builds aliasing and scoping in from the start.
Avoiding Duplicate Record Errors in Rails Under Concurrency
Two concurrent requests can both pass an exists? check and race to insert the same row; here is why, and how to write idempotent Rails controllers.
Catching Database Configuration Drift Between Microservices
Two services sharing a database can pass every test and still fail in production if their DB configuration silently drifts apart.
Building a Test Suite: Pyramid, Layers, and What to Skip
A framework for deciding how much to test: the testing pyramid, layered test responsibility by architecture tier, and what makes test data good.
Testing Non-ASCII Fonts with Prawn and PDF::Inspector
How to debug Unicode font rendering in Ruby's Prawn PDF library and work around PDF::Inspector's limits when testing non-ASCII characters like it.
Upgrading React 17 to 18: Root API, Batching, and Test Fixes
What changes when you upgrade React 17 to 18: the new root API, automatic batching, Strict Mode's double-invoked effects, and test setup fixes.
Upgrading React 16 to 17: Dependencies, Jest, and ESLint Fixes
A practical walkthrough of upgrading a React 16 app to React 17, covering dependency updates, Jest and Enzyme test fixes, and new ESLint warnings.
Upgrading to Rails 7.2: Four Breaking Changes We Hit
Four breaking changes we hit upgrading to Rails 7.2: show_exceptions, array-containment SQL, connection pool locking, and assert_enqueued_email_with.
How Rails Loads Your App: Rake, Console, Server, and Tests
What Rails actually loads when you run a rake task, the console, the server, or tests, and how to load rake tasks in each environment when you need them.