Error matchers in Ruby

A presentation at ParisRB Meetup in May 2020 in Paris, France by Sunny Ripert

Slide 1

Error matchers in Ruby

Slide 2

Sunny

https://github.com/sunny https://twitter.com/sunfox https://sunfox.org

Slide 3

Cults.

La place de marché dédiée à l’impression 3d

https://cults3d.com

Slide 4

! Fail !

Slide 5

Exceptions

def call(order)

do something…

rescue Net::OpenTimeout, Net::ReadTimeout try_again_later(order) end

Slide 6

Exceptions

def call(order)

do something…

rescue Net::OpenTimeout, Net::ReadTimeout try_again_later(order) rescue Faraday::ConnectionFailed => error if error.message == “execution expired” try_again_later(order) end end

Slide 7

=== matcher in Ruby

Slide 8

module FaradayTimeoutErrorMatcher def self.===(error) error.is_a?(Faraday::ConnectionFailed) && error.message == “execution expired” end end

Slide 9

🎉

def call(order)

do something…

rescue Net::OpenTimeout, Net::ReadTimeout, FaradayTimeoutErrorMatcher try_again_later(order) end

Slide 10

module NetworkTimeoutErrorMatcher def self.===(error) case error when Faraday::ConnectionFailed error.message == “execution expired” when Net::OpenTimeout, Net::ReadTimeout true end end end

Slide 11

🎉🎉🎉

def call(order)

do something…

rescue NetworkTimeoutErrorMatcher try_again_later(order) end

Slide 12

Retriable gem

def call(order) retriable(on: NetworkTimeoutErrorMatcher) do # do something… end end