Pact: Consumer-Driven Contract Testing in Go

Pact is a tool to implement consumer-driven contract testing. Consumer-Driven Contracts is a technique or an attitude to define expectation of one service (consumer) on another service (producer) and test those in isolation without the need to deploy the whole stack or do costly end-to-end tests. Breaking changes can then be efficiently communicated to the team in charge.

Transcript

1. Pact
   Consumer-Driven Contract
   Testing in Go
   

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2. Hi, I’m
   Konrad
   

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5. Bouncer
   Schaffner
   Jet
   Streams
   Video Feed
   Box Office
   Persist segments
   Persist ticket
   Android
   App
   iOS
   App
   Web
   Player
   Play livestream
   Tickets
   Purchase tickets
   Validate ticket
   Deliver playlist
   

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6. Bouncer
   Schaffner
   Jet
   Streams
   Video Feed
   Box Office
   Persist segments
   Persist ticket
   Android
   App
   iOS
   App
   Web
   Player
   Play livestream
   Tickets
   Purchase tickets
   Validate ticket
   Deliver playlist
   

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7. What’s wrong with testing?
   ● Too few tests? You’re doing it wrong.
   ● Too many tests? You’re doing it wrong.
   End-to-End Tests
   ● Need to deploy multiple services together in a separate environment
   ● More scope, will take longer to execute
   ● Deploy which version of each service?
   ● Harder to diagnose errors
   ● Multiple end-to-end tests result in redundant test coverage
   

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8. Test Ownership in End-to-End Tests
   ● Who writes the end-to-end tests?
   ● Shared ownership
   ● Metaversion: version number for the whole system
   ● It becomes okay to change and deploy multiple services at once
   ● Introduces coupling into a microservice architecture
   ● Defeating the whole purpose of using microservices in the first place
   “Now you have 2.1.0 problems.”
   — Brandon Byar
   

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9. Pact to the Rescue
   

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10. Consumer-Driven Contract (CDC)
    ● Consumer and Producer are services
    ● Consumer has expectations on a Producer
    ● The expectations are captured in form of a contract
    ● Expectations can be run in isolation of the consumer services
    ● Producer tests consumer provided contract on itself
    ● If something breaks it becomes obvious which consumer is affected
    ● Ideally these contracts are run as part of the CI
    

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11. Pact
    ● Started out as a tool written in Ruby
    ● Now a family of frameworks to implement Consumer-Driven Contract testing
    ● Pact is a tool to verify the contracts are satisfied
    Consumer
    Expectations
    using Pact DSL
    Pact Mock Server Generate Pact
    Contract (JSON)
    Pact Broker
    Producer
    Pact helper
    Producer service
    

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12. Bouncer API
    ●
    ●
    

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13. Bouncer
    Schaffner
    Box Office
    Persist ticket
    Validate ticket
    Consumer
    Consumer
    Producer
    

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16. Bouncer
    Schaffner
    Box Office
    Persist ticket
    Validate ticket
    Consumer v1
    Consumer v1
    Producer v1
    

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17. Bouncer
    Schaffner
    Box Office
    Consumer v1
    Consumer v1
    Producer v2
    JSON
    JSON
    

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18. Bouncer
    Schaffner
    Box Office
    Consumer v2
    Consumer v1
    Producer v2
    JSON
    JSON
    

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19. Pact for Go
    Pact Foundation Documentation https://pact.io
    Pact for Go
    https://github.com/pact-foundation/pact-go
    #pact
    https://gophers.slack.com
    

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20. It’s About Conversation
    ● In agile stories are seen as a placeholder for a conversation
    ● For CDC the same argument applies
    ● Codification of a set of discussions about the service API
    ● If they break: it becomes a conversation
    ● Value in CDC: semi-automates this conversation
    ● CDC is an investment and comes at a cost
    ● Takes a lot of time to set this up and get everyone used to it
    

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21. Thanks
    We are hiring http://jobs.tape.tv
    Ping me konrad.reiche@gmail.com
    Follow me @konradreiche
    

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