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custom_failure_message

❌ Customize Failure Messages

Providing clear failure messages makes debugging easier when a spec fails. Define failure_message (and failure_message_when_negated) for custom output.

# spec/support/matchers/have_multiple_of.rb
RSpec::Matchers.define :have_multiple_of do |divisor|
match do |actual|
actual % divisor == 0
end

failure_message do |actual|
"expected \"#{actual}\" to be a multiple of \\