Custom RSpec matchers and support code need a clear home in spec/support to keep specs DRY and make shared helpers available everywhere.

Webpacker 4 and Babel 7 change config files, package names, asset paths, and polyfill imports when upgrading a Rails app from Webpack 3.

Moving a Rails app from the Asset Pipeline to Webpacker requires inventorying bundled libraries, repackaging legacy assets, and adjusting deployment for pack-based assets.

Pseudo-element styles are hard to inspect directly, but getComputedStyle can read ::before and ::after values for testing and color checks.

Controller specs reset the Rails session on every request, so data written earlier disappears between calls. Stubbing controller.session with a shared TestSession preserves state for testing.

PostgreSQL OVERLAPS treats date ranges as start <= time < end, so boundary dates are excluded and adjacent ranges do not match.

Serve raw GitHub files with correct Content-Type headers for CDN-style testing or prototyping, but without any uptime guarantee.

Create .xls files with the spreadsheet gem and apply number formats for currency and dates, including cell links.

Shared example groups need a clear home in RSpec, since the default rspec-rails layout does not provide one. Organizing them in dedicated shared_examples folders keeps them reusable and easy to load.

Ruby and curl requests can fail when a server only accepts older SSL/TLS versions; forcing a specific protocol version can restore connectivity.

Updating Cucumber on Rails 3+ requires refreshing cucumber, capybara, and cucumber-rails, then restoring any custom support setup after installation.

Bugs in select-field ordering can make form choices appear in the wrong sequence; a sorting check helps verify ordered and unordered dropdowns behave correctly.

OAuth query parameters with nonces or timestamps make VCR request matching fail because each URI changes. A custom matcher can ignore the variable OAuth values.

Cucumber can list step definitions separately, helping detect dead or duplicate steps before cleanup. --dry-run and --format stepdefs reveal candidates, but nested step calls can look unused.

Chaining Capybara matchers with and retries the full expectation when one check fails, making multiple assertions more reliable on pages that change asynchronously.

cucumber_spinner adds a progress bar for Cucumber features and shows failing scenarios immediately, with optional browser opening for failed pages.

Rails apps upgrading to Cucumber 3 often need gem updates, new tag syntax, and step-definition fixes to avoid parser and argument-mismatch errors.

Rails database tasks can fail with ActiveRecord::EnvironmentMismatchError after restoring a dump from another environment. Updating ar_internal_metadata or disabling the environment check lets rails db:drop proceed.

Mixed content behavior differs when secure pages load assets over HTTPS versus HTTP, exposing browser handling of blocked or downgraded resources.

Secure pages linking to insecure destinations suppress the Referer header, making visits appear as direct traffic and breaking source tracking.

Built-in Chrome auditing checks performance, accessibility, and other quality signals for web apps, including private or local pages. Development settings can skew results; Webpagetest is an alternative.

Previewing Rails emails in the browser catches layout and content issues before delivery and helps keep mailer output aligned with expectations.

VCR cassettes can bloat with base64-encoded vision payloads and leaked Basic Auth credentials; sanitizing request bodies and custom matching keep recordings small and playback reliable.

RSpec hook order matters when around(:all) and around(:each) wrap setup and teardown; their execution timing differs from before and after hooks.