Selenium WebDriver 4 can pick an incompatible browser binary in CI, breaking feature tests when Chromium and Chrome versions differ. Setting binary avoids selenium-manager selecting or downloading the wrong browser.

PostgreSQL array queries in Rails match element order, so [16, 17] and [17, 16] are different. Order-independent matching needs normalization or bidirectional containment.

Run Jasmine specs through Rails E2E tests to catch JavaScript failures in regular test runs and verify the runner finishes with all specs passing.

Useful Chrome DevTools console tricks for editing pages, timing code, inspecting elements, and reusing previous results.

Uploaded HTML or SVG can execute JavaScript and steal session cookies; safer uploads rely on extension allowlists, strict CSP, attachment disposition, or octet-stream delivery.

Use git worktree to keep multiple working trees on one repository, so you can test, compare versions, and switch branches without disturbing current work.

Removing CarrierWave attachments outside forms can affect the database and file storage differently. update!(remove_avatar: true) matches normal form behavior and is usually the safest choice.

Time zone-aware projects need Time.current, Date.current, and DateTime.current so values persist correctly; Time.now can write timestamps with the wrong zone.

View specs can stay fast and readable by querying rendered HTML with Capybara finders and matchers instead of relying on heavier request or feature specs.

RSpec’s and_wrap_original can attach expectations to objects created during a call, making it easier to verify the right validator instance without relying on expect_any_instance_of.

Whenever can misread 24-hour times without a leading zero, turning 3:00 into 3pm instead of 3am. chronic_options can switch parsing to a 24-hour clock.

RSpec diffs can mislead when matchers print like failures or when Time.now values differ only by milliseconds.

Custom Cucumber selectors in Spreewald make it easy to target repeated form fields by ordinal position, but :nth-of-type can break when surrounding HTML changes.

Persisting RSpec example status lets failed tests be rerun quickly during development with --only-failures or --next-failure.

Ruby Method objects make it easier to inspect a method’s owner, signature, source, and definition site during debugging, especially when behavior changes across loaded code.

rbenv-each runs a command across every installed Ruby version, useful for updating global gems like bundler, rubygems, or other tools outside a Gemfile.

Adjacent vertical margins in CSS combine by taking the larger value, not the sum, which can create unexpected spacing or prevent consistent component layouts.

Wrong status codes on maintenance pages can deindex sites or cache bad redirects. 503 Service Unavailable with Retry-After preserves SEO during temporary downtime.

ag is a fast text-search tool for source trees, honoring .gitignore and optional .ignore files for fewer matches and better performance.

Devise mail is sent synchronously by default; deliver_later can log sensitive password reset tokens through ActiveJob. A custom mail delivery job disables argument logging.

JavaScript timeout and promise callbacks can run out of queue order because tasks and microtasks follow different scheduling rules.