Microservices are all the rage right now. Breaking up code into small independent services has many benefits, but on the downside, it increases the number of integration points, which increases the amount of integration testing required. How can we be confident that all our services will work correctly together, without being burdened by complex and brittle integration tests? Learn how Pact solves this problem by using consumer driven contracts.

1. Pacts to the rescue!
Making your microservices play nicely together
with Consumer Driven Contracts
Beth Skurrie
@bethesque / @pact_up
bskurrie@dius.com.au

2. “Integrated tests are a scam.
A self replicating virus
that threatens
the very health of your codebase,
your sanity,
and I'm not exaggerating when I
say,
your life.”
- JB Rainsberger

3. Integrated Tests: The Problems
! Slow
! Easy to break
! Hard to fix
! Scales combinatorially
3 classes, 4 code paths each
4 * 4 * 4 = 64 tests

4. A B
mock
Test Symmetry… how it works

5. Test
1
Test
2
Test
3
Integrated tests

7. ! Lack of automated tools
! Relies on developer eternal vigilance
! Does not scale
Test Symmetry: The Problem

8. Do we have the technology to achieve test
symmetry?
Posed to DiUS

9. Slower Easier to break
Harder to fix Scales BADLY
Lots of infrastructure
False negativesLots of set up
System Integration Tests

10. Pact to the rescue!!!

11. A B
mock
C P
pact
Pact… how it works

12. Slower Easier to break
Harder to fix Scales BADLY
Lots of infrastructure
False negativesLots of set up
System Integration Tests

13. Fast Stable
Easy to debug Reliable
No extra infrastructure
Low setupScales linearly
Pact

14. Better API design!

15. Arrange - set up mock server

16. Arrange - set up mock server

17. Arrange - set up mock server

18. Arrange - set up expectations

19. Arrange - set up expectations

20. Arrange - set up expectations

21. Act and Assert

22. Act and Assert

24. Act and Assert

25. Act and Assert

26. Act and Assert

27. Set up test data
Consumer assumed:
Provider complies:

28. Set up test data
Consumer assumed:
Provider complies:

29. Verify: Fail

30. Verify: Success!

31. Postel’s law

32. Sharing pacts

33. P
publish pact latest pact
C
Pact
Broker
Pact Broker - Share pacts

34. Pact Broker - Autogenerated documentation

35. Pact Broker - Network graph

36. Support
! JSON is language independent
! Ruby
! JVM (Java and Scala)
! .net
! Javascript (consumer side, provider side WIP)
! Pact specification

37. “How is it working for you?”

38. Fast feedback in isolation
+
Early detection
+
Rapid recovery

39. Pact allows you to:
! Combine the advantages of integrated tests and test symmetry
! Mitigates the shortcomings of each method
! Allows you to modify components with agility - quick feedback
on potential breakages
! Have confidence that all the services in your system will work
together
! Throw away your integration tests!!!

40. Pact
Makes your microservices play nicely together
with Consumer Driven Contracts
github.com/realestate-com-au/pact
@pact_up
Beth Skurrie
bskurrie@dius.com.au
@bethesque
• Regular expressions & type
based matching
• Why doesn’t Pact use JSON
Schema?
• How to avoid versioning APIs
• How to use Pact between teams
• Should I use Pact for testing
external APIs?
• How not to do it
• And moar!