The primary goal of the microservice architecture is to enable the rapid, reliable delivery of software with DevOps. One of the pillars of DevOps is automated testing, yet many organizations attempt to adopt microservices while still doing manual testing. What’s more, the microservice architecture has its own distinctive automated testing challenges. This presentation describes how to descend the testing pyramid and replace slow, brittle, end-to-end tests with faster, more reliable tests for individual services. You will learn how to write tests that ensure that service APIs evolve while preserving backward compatibility. You’ll learn how, by running these tests in a deployment pipeline, you will fully benefit from microservices.

1. @crichardson
Descending the test
pyramid
Copyright © 2019. Chris Richardson Consulting, Inc. All rights reserved
Chris Richardson
Founder of Eventuate.io
Founder of the original CloudFoundry.com
Author of POJOs in Action and Microservices Patterns
@crichardson
chris@chrisrichardson.net
https://adopt.microservices.io

2. @crichardson
Presentation goal
Effective testing
strategies for
microservices

3. @crichardson
About Chris
http://adopt.microservices.io

4. @crichardson
About Chris
https://microservices.io/book
40% discount with code
ctworaclecodeone19

5. About Chris: microservices.io
Microservices pattern
language
Articles
Example code
Microservices Assessment
Platform

6. @crichardson
Agenda
Overview of testing microservices
Unit testing
Integration testing
Component testing
End to end testing
Testing in production

7. @crichardson
The state of automated testing
today: Oops!
https://cdn.agilitycms.com/sauce-labs/white-papers/sauce-labs-state-of-testing-2018.pdf
😢

8. @crichardson
+
Marketplace is volatile, uncertain, complex
and ambiguous
+
Businesses must innovate faster
Deliver software rapidly, frequently and reliably
Software

9. Daily
Commits
Use DevOps & Continuous
Delivery/Deployment
A highly testable
and deployable architecture is
essential
ApplicationAutomated deployment pipeline
Production
Source code
repository
Automated testing is essential

10. @crichardson
The problem with a large,
complex monolith
Time
Maintainability
Testability
Deployability
Modularity
Evolvability
Size/
Complexity
-ilities required to be competitive
Risk of
disruption

11. The microservice architecture is
an architectural style
that structures an application as a
set of services
Each microservice is:
• highly maintainable and testable
• loosely coupled
• independently deployable
• organized around business capabilities
• owned by a small team

12. @crichardson
Autonomous service teams
Order
Service
Automated deployment pipeline
Source code repository
Kitchen
Service
Automated deployment pipeline
Source code repository
Delivery
Service
Automated deployment pipeline
Source code repository
Production
Orders Team
Kitchen Team
Delivery Team

13. @crichardson
Microservices enable DevOps
DevOps requires automated testing
Complexity of microservices requires good
automated testing
Using the Microservice Architecture
without automated testing
is self-defeating AND risky
http://bit.ly/msa-antipattern-flying-before-walking

14. @crichardson
What is a test?
Test
System
under test
(SUT)
Verifies behavior
• SUT = thing being tested = class … entire application
• Collection of tests = Test Suite

15. @crichardson
The testing pyramid and
microservices
Unit
Integration
Includes consumer-driven contract tests
Component
End to End
Classes within
service
A services adapters
An entire service
Multiple services or application
Brittle, Slow,
Costly
Reliable, Fast,
Cheap

16. Agenda
Overview of testing
microservices
Unit testing
Integration testing
Component testing
End to end testing
Testing in production Unit
testing Unit
Integration
Component
End to End

17. @crichardson
About unit tests
Test
Class or
cluster of
classes
Test
Double
Test
Double
Dependency
Dependency
Dependen
Simulates
dependency
SUT

18. @crichardson
Business logic
Controller
POST /something
GET /something/id
Database
Database
adapter
Inbound
Message
Adapter
Repository
Service
Entity
Value object
Outbound
Message
Adapter
Unit test
Unit test
Unit test
Saga
<<Message Channel>>
<<Message Channel>>
Primary focus is
the business logic
“algorithms"
Unit testing
adapters is
sometimes useful
Maybe unit test
coordination logic

19. @crichardson
Unit test selectively
http://blog.stevensanderson.com/2009/11/04/selective-unit-testing-costs-and-benefits/
Cost of unit testing = # dependencies
Benefit of
unit testing
=
non-obviousness
High
HighLow
Low
Algorithms
Trivial code Coordinators
Overly
complex
code
(rewrite)

20. Agenda
Overview of testing
microservices
Unit testing
Integration testing
Component testing
End to end testing
Testing in production
Unit
Integration
Component
End to End

21. About integration testing
Inbound adapters:
HTTP controller
…
Outbound adapters:
HTTP proxy
DAO
Messaging adapter
…
Integration
Test
Adapter
Verifies
behavior
Adapter Adapter
AdapterAdapter
Service

22. @crichardson
Integration testing persistence
code

23. @crichardson
Inter-service dependencies integration
testing

24. @crichardson
Consumer-driven contract
testing
Verify that
a service (a.k.a. provider)
and its clients (a.k.a. consumers)
can communicate while testing
them in isolation

25. @crichardson
Contract testing example
Api Gateway
Order
Service
Proxy
Order Service
Order
Controller
GET /orders/{id}
ProviderConsumer

26. @crichardson
Contract testing example
Request from consumer
Response from service
Describes
Written by
API Gateway
Team API definition
by example
Order
Service
Proxy
Order
Controller
GET /orders/{id}
ProviderConsumer

27. @crichardson
Consumer-side contract test
OrderService
Proxy
Order
ServiceProxy
Tests
Use
WireMock-
based
Order Service
Test Double
Configures
Verify that proxy makes
requests that match
contract and can consume
responses
“service virtualization”
GET /orders/{id}

28. @crichardson
Provider-side contract test
Class BaseHttp {
}
class HttpTest
extends
BaseHttp {…
Spring Cloud
Contract
Code
generates
Reads
Configures
with mock
OrderRepository
Order
Controller
Tests
Order
Repository
Must be
consistent
Verify API
structure matches
contracts
GET /orders/{id}

29. @crichardson
Assumption:
If consumer and provider are tested
independently with the same contracts
Consumer and provider can communicate
OrderService
Proxy
Order
Controller
Test Test

30. @crichardson
Agenda
Overview of testing microservices
Unit testing
Integration testing
Component testing
End to end testing
Testing in production
Unit
Integration
Component
End to End

31. Goal of component testing
Minimalist
Verify that the container is
deployable
Passes health check
…
VS.
Acceptance tests
Real world/user focussed
But avoid duplicating unit and
integration tests
Component
Test
Service
Verifies
behavior
In isolation

32. @crichardson
Test process (eg. JVM)
In-process component testing
In-memory
database
Test
Some Service
REST API
Outbound adapter, eg. Service Proxy
Mock IPC, e.g. RestTemplate/Messaging
Some other service
Messaging API
Configures mocks

33. @crichardson

34. @crichardson
Out-of-process component
testing
Real
Database
Test
Some Service
REST API
Mock
Other Service
REST API
Message
Broker
Configures mocks
Separate
process,
e.g Docker
container
Exchanges messages

35. About WireMock: Mockito for
HTTP servers
http://wiremock.org/
@Test
public void shouldProxyCreateOrder() {
…
stubFor(post(urlEqualTo("/orders"))
.willReturn(
aResponse()
.withStatus(200)
.withHeader("Content-Type",
"application/json")
.withBody(expectedResponse)));
…
verify(postRequestedFor(
urlMatching("/orders")));
}

36. @crichardson
Running out of process component
tests: $ ./gradlew componentTest
= @Before/@After

37. @crichardson
In-process vs out-of-process
Benefits Drawbacks
In-process
Simpler
Faster
Less realistic
Out-of-process More realistic
Slower
More complex

38. @crichardson
Agenda
Overview of testing microservices
Unit testing
Integration testing
Component testing
End to end testing
Testing in production Unit
Integration
Component
End to End

39. @crichardson
End to End testing verifies
behavior of application
End to End
Test
FTGO application
Order
Service
Consumer
Service
…
https://docs.cucumber.io/gherkin/

40. @crichardson
Application
Deployment pipeline
Running end to end tests
Order Service deployment
pipeline
Kitchen Service deployment
pipeline
Delivery Service deployment
pipeline
….
End to End
tests
Production

41. About scenario-based end-to-
end testing
Typically, BDD user scenarios = original
requirements user focussed/real
world
Parallelization can accelerate testing
BUT
Duplicates tests lower down the
pyramid
Brittle, slow, complex
Potential bottleneck that delays getting
changes (e.g. bug fixes) into production
Use selectively based on risk
My Bank App
Given …
When …
Then …
Loan
Repayment
Calculator
Loan
Document
Generator
Slow External
Service
Bottleneck

42. @crichardson
Replace end-to-end tests with
per-service (component) tests
My Bank App
Given …
When …
Then …
Loan
Repayment
Calculator
Loan
Document
Generator
Slow External
Service
My Bank App
Loan
Repayment
Calculator
Loan
Document
Generator
Slow external
Service
Given …
When …
Then …
Given …
When …
Then …
Bottleneck only for
Loan Document
Generator

43. @crichardson
Agenda
Overview of testing microservices
Unit testing
Integration testing
Component testing
End to end testing
Testing in production

44. @crichardson
https://blogs.msdn.microsoft.com/seliot/2011/04/25/i-dont-always-test-
my-code-but-when-i-do-i-do-it-in-production/

45. @crichardson
Test environment != production
Issues will appear in production

46. @crichardson
Testing in production*
Separate
Deployment - running in production
Release - available to users
Test code
Before releasing
When releasing
Automate for fast deployment, rollback and roll forward
* a.k.a. Validation in production
https://medium.com/@copyconstruct/testing-in-production-the-safe-way-18ca102d0ef1

47. Order Service
V1
Order Service
V2
Test deployed code before
releasing: e.g. Canary release
1.Deploy V2 alongside V1
2.Test V2
3.Route test traffic to V2
4.Release V2 to a small % of production
users
5.Monitor/test (latency, errors) - undo
rollout if errors
6. Increase % of production traffic going
to V2
7.Repeat until 100% of traffic going to V2
8.Eventually undeploy V1
Intelligent
traffic router
Order Service
V1
Order Service
V2
Monitoring system

48. Feature toggles/flags
A toggle controls which of several
code paths is used
Release toggle - allow incomplete
code to be safely committed/
deployed during trunk based
development
Ops toggles - enable Ops to
enable/disable features
Permissioning toggles - user
attribute features/experience
Experiment toggles - e.g. A/B
testing
https://martinfowler.com/articles/feature-toggles.html

49. @crichardson
Summary
Use the microservice architecture accelerate software delivery by
improving testability and deployability
Using microservices without automated testing is self-defeating AND risky
Accelerate the deployment pipeline by pushing testing as far down the
test pyramid as possible
End-to-end tests:
Use selectively
Replace with per-service tests as much as possible
Test in production for reliable deployments/releases

50. @crichardson
@crichardson chris@chrisrichardson.net
http://adopt.microservices.io
Questions?
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