Microservices have become mainstream now. We're able to respond to changing requirements and ship code to production more quickly than ever. Or, we were for our first microservice. And even our second and third. But 5 years down the track, what happens when we end up with tens or hundreds of microservices that are now part of our core product - how do we know that we're safe to deploy to production without running hours of complex integration tests, defeating the purpose of using microservices in the first place? Find out how contract tests can keep your microservices free from the burden of integration testing, and allow you to ship your code with speed and confidence.

1. 1
Microservices:
Test smarter not harder
Beth Skurrie (DiUS)
@bethesque

2. A big problem
soundify

3. Long time to market
soundify

4. WHAT WE ARE KNOWN FOR
4
Microservices
Solved problems New problems
● Integration tests
○ Slow tests
○ Easy to break
○ Hard to fix
○ Scale badly
○ Lots of set up
○ Flakey tests ignored
○ Takes dev time away
from features
● Feature time to market
A STORY

5. 5
To E2E test, or not to E2E test?
A STORY

6. 6
What if there was another way?

7. 7
C P
mock
ANOTHER WAY

8. WHAT WE ARE KNOWN FOR
8
Test symmetry
Solved problems New problems
● Hard to keep both sides in
sync
● Fast feedback
● Few dependencies
● No dedicated environment
● Reliable
● Easy to debug
ANOTHER WAY

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C P
mock
ANOTHER WAY

10. 10
C P
mock
ANOTHER WAY

11. PPCC
mock
contract
ANOTHER WAY

12. WHAT WE ARE KNOWN FOR
12
Contracts
Solved problems New problems
● ???● Keeping tests in sync
ANOTHER WAY

13. Bug turnaround -
minutes
Contracts tests
ANOTHER WAY

14. Know before you
commit
Contracts tests
ANOTHER WAY

15. Make changes with
speed and confidence
Contracts tests
ANOTHER WAY

16. Deploy independently
Contracts tests
ANOTHER WAY

17. Better API design
(Consumer)
Contracts tests
ANOTHER WAY

18. Are not functional tests
Contracts tests
ANOTHER WAY

19. Are not load
performance tests SLAs
Contracts tests
ANOTHER WAY

20. Are not good for “public”
APIs (many, unknown
consumers)
(Consumer)
Contracts tests
ANOTHER WAY

21. Are not a silver bullet!
Contracts tests
ANOTHER WAY

22. 22
ANOTHER WAY

23. 23
Do I still need integration tests?
ANOTHER WAY

24. 24
Integration test coverage
Consequences of bug
x
Time to find bug
x
Time to release fix
ANOTHER WAY

25. WHAT WE ARE KNOWN FOR
25
Speed up your releases
Do less Do more
● Aggregated logging
● Metrics
● Semantic monitoring
● Alerting
● Correlation IDs
● Integration testing
ANOTHER WAY

26. The journey continues

27. 27
● Open source
● Multiple languages
○ JVM
○ .NET
○ Javascript
○ Python
○ Go
○ + more
pact.io
● HTTP contracts
● Message contracts

28. 28
A B
mock
C P
contract
A CONTRACT TESTING JOURNEY

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A CONTRACT TESTING JOURNEY

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Pact Broker
A CONTRACT TESTING JOURNEY

31. 31
Automate the contract exchange
A CONTRACT TESTING JOURNEY

32. 32
WHEN
the provider receives
<some request>
THEN
it will return
<some response>
A CONTRACT TESTING JOURNEY

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WHEN
the provider receives
a GET request for /alligators/Mary
THEN
it will return
a 200 OK response
with a JSON body {“name”: “Mary”}
A CONTRACT TESTING JOURNEY

34. 34
WHEN
the provider receives
a GET request for /alligators/Mary
THEN
it will return
a 404 Not Found
response
a 200 OK
response
A CONTRACT TESTING JOURNEY

35. 35
GIVEN
<the provider is in a certain state>
WHEN
the provider receives
<some request>
THEN
it will return
<some response>
A CONTRACT TESTING JOURNEY

36. 36
You still need to think about test
data
A CONTRACT TESTING JOURNEY

37. A contract testing
journey
● Automate the contract exchange
● You still need to think about test
data
A CONTRACT TESTING JOURNEY

38. 38
Contracts should focus on the
messages, not the technology
A CONTRACT TESTING JOURNEY

39. A contract testing
journey
● Automate the contract exchange
● You still need to think about test data
● Contracts should focus on the
messages, not the technology
A CONTRACT TESTING JOURNEY

40. 40
Contracts should be as flexible as
possible - but no more
A CONTRACT TESTING JOURNEY

41. A contract testing
journey
● Automate the contract exchange
● You still need to think about test data
● Contracts should focus on the
messages, not the technology
● Contracts should be as flexible as
possible - but no more
A CONTRACT TESTING JOURNEY

42. 42
The other service needs to know when a
contract has changed
You need a way to introduce changes without
breaking everything
Contracts are not a substitute for good
communication between teams
A CONTRACT TESTING JOURNEY

43. 43
Pact Broker webhooks
A CONTRACT TESTING JOURNEY

44. 44
Pact Broker tags
A CONTRACT TESTING JOURNEY

45. 45
Contracts are STILL not a substitute for
good communication between teams
A CONTRACT TESTING JOURNEY

46. ● Automate the contract exchange
● You still need to think about test data
● Contracts should focus on the
messages, not the technology
● Contracts should be as flexible as
possible - but no more
● The provider needs to know when a
contract has changed
● You need a way to introduce
changes without breaking
everything
● Remember: contracts are not a
substitute for good communication
between teams
A contract testing
journey
A CONTRACT TESTING JOURNEY

47. 47
A CONTRACT TESTING JOURNEY

48. 48
You need to share the verification
results as well as the contracts
A CONTRACT TESTING JOURNEY

49. 49
Pact Broker verifications
A CONTRACT TESTING JOURNEY

50. 50
A CONTRACT TESTING JOURNEY

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A CONTRACT TESTING JOURNEY

52. 52
If you can’t deploy your services
independently,
you don’t have microservices.
You have a distributed monolith.
A CONTRACT TESTING JOURNEY

53. 53
If you can’t deploy your services
independently,
you don’t have microservices.
You have a distributed monolith.
A CONTRACT TESTING JOURNEY
Warning!
Don’t build a
distributed monolith

54. 54
Consumer
version
Provider
version
Verification
result
11 31 success
12 31 failure
12 32 success
13 32 success
14 unknown
“The Matrix”
A CONTRACT TESTING JOURNEY

55. 55
A CONTRACT TESTING JOURNEY

56. 56
A CONTRACT TESTING JOURNEY

57. 57
A CONTRACT TESTING JOURNEY

58. 58
What about Swagger/Open API?
OTHER TOOLS

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Provider contracts
OTHER TOOLS

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Consumer contracts
OTHER TOOLS

61. 61
A B
mock/write
C P
pact swagger
verify
verify
Pact+Swagger
OTHER TOOLS

62. 62
Message Pact
OTHER TOOLS
C P
contract

63. The talk ends,
but the journey continues

64. WHAT WE ARE KNOWN FOR
64
Contracts
Solved problems New problems
● ???● Deliver faster

65. 65
pact.io
dius.tech/contrca4a
slack.pact.io
@pact_up
Microservices: Test SMARTER not HARDER
Beth Skurrie (DiUS)
@bethesque

66. 66
Contract