Seb Rose presented on microservice delivery and contract testing. He discussed managing dependencies between services, decoupling services using test doubles, and implementing contract tests with Pact to define and test the interactions between services. Pact uses a mock server to test contracts and a broker to publish pacts and coordinate verification between teams to enable independent deployment of services.

1. Micro-service delivery
without the pitfalls
Seb Rose
Twitter:
@sebrose
Blog:
https://cucumber.io/blog/
E-mail:
seb.rose@smartbear.com

2. @sebrose h
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Agenda
So
ft
ware contracts
Managing dependencies
Decoupling with test doubles
Contract tests
Pact & Pact Broker
Q & A

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Dependencies
X
Contracts

4. @sebrose h
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Consumer & provider
C P
Contract

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Design by contract
Design by contract
Contract
• an agreement between client
and supplier
Characteris
ti
cs
• expect some bene
fi
ts
• incur some obliga
ti
ons

6. @sebrose h
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Agenda
So
ft
ware contracts
Managing dependencies
Decoupling with test doubles
Contract tests
Pact & Pact Broker
Q & A

7. @sebrose h
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CI Staging Prod
C3 C2 C1
P3 P2 P1
CI - consumer & provider
Test Test Test
Test
Test Test Test

8. @sebrose h
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You have a distributed monolith
Beth Skurrie
If you can’t deploy services
independently, you don’t have
micro-services.

9. @sebrose h
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Agenda
So
ft
ware contracts
Managing dependencies
Decoupling with test doubles
Contract tests
Pact & Pact Broker
Q & A

10. @sebrose h
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C
C
Collaboration tests
Test
double
Common approach
Collaboration
Collaboration
Test
Production P

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C
C
Collaboration tests
Test
double
Success!
Collaboration
Test
Production P

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C
C
Collaboration tests
Test
double
Fail
Collaboration
Test
Production
Incorrect behaviour
P

13. @sebrose h
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Agenda
So
ft
ware contracts
Managing dependencies
Decoupling with test doubles
Contract tests
Pact & Pact Broker
Q & A

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JB Rainsberger, via GOOS mailing list, “Unit-test mock/stub assumptions rots”
15 March 2012
Systema
ti
c contract tes
ti
ng
• Collabora
ti
on tests make
assump
ti
ons about the contract
• Contract tests try to jus
ti
fy those
assump
ti
ons
JB Rainsberger, via GOOS mailing list, “Unit-test mock/stub assumptions rots”
15 March 2012

15. @sebrose h
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Test
double
Contract test
Contract Test
P

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Test
double
I
n
t
e
r
f
a
c
e
Hand-rolled
contract tests
Contract Test

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Agenda
So
ft
ware contracts
Managing dependencies
Decoupling with test doubles
Contract tests
Pact & Pact Broker
Q & A

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Pact provides a mechanism for crea
ti
ng a
contract between a service consumer and a
service provider, and then providing the tools
to validate that the consumer and provider
adhere to the contact independently of each
other.
https://dius.com.au/2014/05/19/simplifying-micro-service-testing-with-pacts/
Simplifying micro-service tes
ti
ng

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•Consumer creates contracts using Pact DSL
•When consumer tests are run:
•Pact creates a mock HTTP server
•a Pact
fi
le is created
•Provider uses Pact
fi
le to verify compa
ti
bility
•Provider may o
ff
er “backdoor” interface
Pact - key points

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https://www.youtube.com/watch?v=79GKBYSqMIo

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https://www.youtube.com/watch?v=79GKBYSqMIo

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https://www.youtube.com/watch?v=79GKBYSqMIo
“Matrix”

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CI Staging Prod
V32 V29 V27
Complica
ti
ons
W3 W2
X9 X8 X7
Y15 Y14 Y9
Z84 Z73 Z72

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• Pacts are published by Consumer
• Pacts are fetched by Provider
• Results are stored in the “Matrix”
• “Matrix” supports independent deployment
Pact broker - key points

25. @sebrose h
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Pact
fl
ow is the complete contract testing solution
allowing teams to orchestrate and scale their contract
testing initiative.
Visibility to focus on what ma
tt
ers
With Pact
fl
ow, developers can
fi
nd and
fi
x integration
errors earlier in the SDLC and teams can improve
communication & collaboration, reduce reliance on
E2E tests resulting in faster and safer deployments.

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•Increases con
fi
dence
•Reduces need for integra
ti
on tests
•Speeds up development
•No subs
ti
tute for communica
ti
on
•Does not replace all other tes
ti
ng
Take aways

27. Seb Rose
Twitter:
@sebrose
Blog:
https://cucumber.io/blog/
E-mail:
seb.rose@smartbear.com
http://bddbooks.com