Show long errors in RSpec

eq_long_string_matcher.rb

RSpec::Matchers.define :eq_long_string do |expected|
  match do |string|
    expected == string
  end

  failure_message do |actual|
    "Failed with [#{actual}]\n\n" \
      "Expected [#{expected}]"
  end

  failure_message_when_negated do |actual|
    "Failed with [#{actual}]\n\n" \
      "Expected [#{expected}]"
  end

  description do
    "Comparing long strings"
  end
end