Web font loading can delay first paint and cause FOIT, especially on slow connections. Delivery choices, fallback handling, and reduced font variants improve perceived performance.

Tagging RSpec examples and groups lets you filter slow or special cases, assign values, and trigger hooks or module includes by metadata.

Compare two HTML snippets in RSpec while ignoring whitespace, comment nodes, quote style, and attribute order.

i18n-tasks helps keep Rails locale files complete by finding missing and unused translation keys and reducing manual YAML bookkeeping.

Extensive Chrome startup options help build custom browser drivers and automate testing with Capybara.

HTTPS requests fail against self-signed certificates or broken certificate chains unless the correct CA, intermediate cert, or certificate store is configured.

Capistrano 3 can execute an arbitrary shell command across all app servers, useful for grepping logs or bulk remote checks.

Create large placeholder files fast for testing disk usage, storage limits, or performance without writing real data using fallocate.

Rails deployments with Webpacker and Capistrano often need asset-path, manifest, and compile-time tweaks to avoid slow releases and unused compression output.

Authenticated pages can be benchmarked with ab by supplying the right session cookies; otherwise login-protected requests fail or measure the wrong content.

html_safe strings lose $1 and other match variables inside gsub blocks. A SafeBuffer override can restore access to capture groups during replacements.

Capybara now includes an RSpec acceptance-testing DSL, replacing much of Steak’s earlier role and making end-to-end testing in RSpec more seamless.

Capybara warns when selector locators are integers instead of strings or symbols, often in pagination links and numbered clicks.

Jasmine DOM testing is easier with matchers like toBeVisible() and toHaveCss(css), plus fixture loading for temporary HTML setup and cleanup.

Global website checks reveal DNS propagation issues and location-specific rendering problems before users do.

Capybara driver for browser testing with QtWebKit when JavaScript support is needed.

Cucumber feature files can live in subdirectories, but step definitions and support files need an explicit load path. Using -r features keeps subfolder runs working.

Webpacker compiles assets on demand in Rails, which can freeze helpers and slow page reloads when no dev server is running.

Spring can hide code changes while debugging Rails commands because it reuses a cached application process. Disabling it avoids stale behavior in rails and rake runs.

Using === with strings and regexes can change matching behavior in Ruby; match? is only safe when the left side is definitely a regex.

Savon mocks usually require an exact SOAP request body, but message: :any accepts any payload and returns the stubbed XML.

esbuild watch errors stay hidden in the terminal while Rails keeps serving stale assets; writing them to a file lets the app render build failures in development.

Chrome can reject locally generated self-signed certificates and hide HTTPS even when they work. Importing the certificate or launching with --ignore-certificate-errors allows testing.