Lightening Talk: Auckland Continuous Delivery Meetup [Sept 2014] - Pact: Consumer-Driven Contract Testing (Integrated Tests Are A Scam)

Pact – Consumer Driven Contract Testing
Commercial in Confidence | Assurity Consulting Limited 2014
“Integrated Tests Are A Scam”
Pete Sellars – Technical Consultant

Challenge…

Who Writes Integration Test?

Integrated Tests Are A Scam
Integrated tests are a scam—a self-replicating
virus that threatens to infect
your code base, your project, and your
team with endless pain and suffering.

Code Whisperer

Challenge Accepted

Timeline - 2005

Contract Tests – Design By Contract

Timeline - 2006

Contracts Overview
Provider
•Closed & Complete
•Singular & Authorative
•Bounded Stability &
Immutability
Consumer
•Open & Incomplete
•Multiple &
Non-Authorative
Immutability
Consumer-Driven
•Closed & Complete
•Singular &
Non-Authorative
Immutability
Consumer-Driven Contracts, A Service Evolution Pattern: Ian Robinson

Consumer-Driven Contract Benefits
…they focus the specification
and delivery of service
functionality around key
business value drivers.
…give us the fine-grained
insight and rapid feedback we
require to plan changes and
assess their impact on
applications currently in
production
Consumer-Driven Contracts, A Service Evolution Pattern: Ian Robinson

Timeline - 2009

Why Are Integrated Tests A Scam?

Why Are Integrated Tests A Scam
Integrated Tests Are A Scam (2009): J.B. Rainsberger

How to beat the Scam….

Timeline - 2010

Why Are Integrated Tests A Scam?

Why Are Integrated Tests A Scam…
Consider 10 layers with 3
potential branch points
at each layer. Number of
code paths: 310 > 59,000.
How about 4 branch
points per layer? 410 >
1,000,000. How about 3
branch and 12 layers?
312 > 530,000.
How about 3 branch and
12 layers? 312 > 530,000.
Even if one of your 12
layers has a single code
path, 311 > 177,000.
Even if your 10-layer
application has only an
average of 3.5 code
paths per layer, 3.510>
275,0001.
Do you feel lucky?
Do you?

How to beat the Scam…

Sharing Tests!! …
To reduce the chances of unexpected
breaks in integration contracts, it's useful
to move to a Consumer Driven
Contracts approach. You can facilitate this
by letting the supplier team have copies of
your integration contract tests so they can
run them as part of their build pipeline.
Integrtation Contract Tests (2010): Martin Fowler

2010: Writing Consumer-Driven Contracts?

Micro Services

Timeline - 2013

Pact
Testing Interactions with Web Services without Integration Tests In Ruby:
REA Engineering Blog

Pact
Consumer sets up
expectations on a mock
service provider. Mock
service returns the
expected responses.
The requests, and their
expected responses, are
then written to a "pact“
file
The requests in the pact
file are later replayed
against the provider. Actual
responses are checked to
make sure they match the
expected responses.
Integrated Tests Are A Scam (2010):
J.B. Rainsberger

Pact
Testing with Pact: Pact Wiki

Pact
Simplifying Micro-Services Testing with Pacts: Ron Holshausen

Pact Features
Pact Wiki

Pact
We now have fast unit-like
tests on each side of the
integration point instead of
tedious integration tests.
Testing Interactions with Web Services without Integration Tests In Ruby:
REA Engineering Blog

Why Integration Test Are Still A Scam…
Cumulative
# Required;
Slow &
Brittle
Doesn’t
Provide
Coverage
Expected
Encourage
Sloppy
Coding
Integrated Tests Are A Scam

Timeline - 2014

Trial Pact & Pacto
Consumer-Driven Contracts are a testing
approach to help service interfaces evolve
with confidence without unknowingly
breaking consumers. The similarly
named Pact and Pacto are two new open-source
tools which allow testing interactions
between service providers and consumers in
isolation against a contract. Both have grown
out of projects which are building RESTful
microservices and show great promise.
ThoughtWorks Technology Radar: July 2014

Do Things Differently?

References
• Blog Posts
> Contract Testing, J.B. Rainsberger: http://blog.thecodewhisperer.com/2005/03/02/in-brief-contract-tests/
> Integrated Tests Are A Scam, J.B. Rainsberger: http://blog.thecodewhisperer.com/2010/10/16/integrated-tests-are-a-scam/
> IntegrationContractTests, Martin Fowler: http://martinfowler.com/bliki/IntegrationContractTest.html
> Testing Interactions with WebServices without Integration Tests in Ruby, REA Techblog: http://techblog.realestate.com.au/testing-interactions-with-web-services-without-integration-tests-in-ruby/
> Simplifying Micro-Service testing with Pacts, Ron Holshausen: http://dius.com.au/2014/05/19/simplifying-micro-service-testing-with-pacts/
• Articles
> Consumer-Driven Contracts – A Service Evolution Pattern, Ian Robinson: http://www.martinfowler.com/articles/consumerDrivenContracts.html
> Thoughtworks Technology Radar: http://www.thoughtworks.com/radar
> Design By Contract: http://c2.com/cgi/wiki?DesignByContract
• Presentations
> Agile 2009 - Integration Tests Are A Scam, J.B. Rainsberger: http://www.infoq.com/presentations/integration-tests-scam
> Integration Tests Are A Scam (Slides 2010), J.B. Rainsberger: http://www.slideshare.net/agileee/notes-5407051
> DevConFu 2013 – Integrated Tests Are A Scam, J.B. Rainsberger: http://vimeo.com/80533536
> Micro-Service Architecture, Fred George: http://www.slideshare.net/fredgeorge/micro-service-architecure
> Practical Microserices (YOW 2013), Sam Newman: http://www.slideshare.net/spnewman/practical-microservices-yow-2013
> Practical Considerations for Micro-Service Architectures, Sam Newman: http://yow.eventer.com/yow-2013-1080/practical-considerations-for-microservice-architectures-by-sam-newman-1389
• Tools
> Pact: https://github.com/realestate-com-au/pact/wiki
− Provider State Example: https://github.com/realestate-com-au/pact/blob/master/example/zoo-app/spec/service_providers/animal_service_client_spec.rb
− Generated Documentation Example: https://github.com/realestate-com-au/pact/blob/master/example/zoo-app/doc/pacts/markdown/Zoo%20App%20-%20Animal%20Service.md
> Pacto: http://thoughtworks.github.io/pacto/

Lightening Talk: Auckland Continuous Delivery Meetup [Sept 2014] - Pact: Consumer-Driven Contract Testing (Integrated Tests Are A Scam)

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Lightening Talk: Auckland Continuous Delivery Meetup [Sept 2014] - Pact: Consumer-Driven Contract Testing (Integrated Tests Are A Scam)