Rails JSON serializes times with milliseconds, so iso8601 and to_json can differ in RSpec expectations. Using to_json keeps time string comparisons matching.

Run Sidekiq jobs synchronously in development to avoid a separate worker process and benefit from code reloading.

Cucumber failures can open the current page in a browser automatically, avoiding repeated "Then show me the page" reruns and speeding up debugging.

any_instance stubbing and expectations now work in RSpec 2.6, enabling should_receive and stub on instances created inside code.

Nested patiently blocks now wait independently in Spreewald, preventing detached DOM failures when with_scope reuses cached elements.

Selenium can miss browser events such as change during form input; a Cucumber step can fire jQuery-registered events manually with execute_script.

Association values in Machinist blueprints need blocks so Project.make runs per blueprint instance, not once at parse time when RSpec loads.

Lazy let evaluation keeps RSpec examples shorter when a setup call has many required arguments, and lets stubs change the result before the value is used.

RSpec example groups and shared examples can use symbols as names, even though the official docs do not mention it.

Capybara find can return incorrect matches when called on nodes from all, especially with text filters. Use a full selector on the page to scope the search reliably.

Run multiple example or scenario line numbers from one file with rspec or cucumber, using colon-separated targets instead of separate commands.

Polymorphic associations in Cucumber Factory require named associations; indirect references like owner above fail when the target type is ambiguous.

BEM-style selectors can be generated from plain-language Cucumber locators, reducing repetitive typing when mapping readable step text to CSS classes.

Cucumber docstrings break when nested triple double quotes appear inside the text; escaping or a Transform can preserve embedded quote markers.

Cucumber factory now infers the model class from the factory, so steps can use natural names like admin instead of user (admin).

Tight should_receive(...).with(...) expectations on hashes are brittle and produce unreadable failures. Block-based argument checks keep RSpec assertions clearer and more flexible.

Clicking elements by raw CSS selector is brittle; selector_for lets feature steps use plain English names like sidebar instead.

Threaded web server benchmark can exhaust application resources more effectively than ApacheBench or httperf; libev is required for installation.

Capybara and Cucumber can verify that a select box includes a disabled choice, using an XPath check on the matching option element.

CucumberFactory 1.11 adds support for FactoryGirl traits, letting Cucumber steps create records with named variations such as vintage and moody.

attribute? often checks presence like attribute.present?, but numeric values and associations behave differently; 0 can be false for ActiveRecord query attributes.

Mock expectations in RSpec can linger across examples; resetting a proxy removes the configured doubles and returns the object to its original state.

Gem for instantly showing failing specs while continuing to run the rest of the suite, instead of aborting on the first failure.