- Why Spring Boot for REST? - Why bother write tests? - Spring Test Framework Overview - Reviewing Test Results

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Testing REST with Spring
Kostiantyn Baranov
Senior Software Engineer
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● 6 years at GL
● Trainer & Mentor at GL Training Center
● Works with Microservice architecture based on Spring and
Spring Boot, Gradle & Docker with AWS
About myself

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● Why Spring Boot for REST
● Why bother write tests?
● Spring Test Framework Overview
● Reviewing Test Results
Agenda

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● Spring Test Framework
● jUnit 4
● Spring RestDocs
● Allure
Demo

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REST with Spring Boot

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Spring Ecosystem

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Spring MVC Framework
● Supports RESTful URLs
● Annotation based configuration
● Flexible in supporting different Views

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● Based on Spring MVC
● JSON/XML/Hypermedia Support
● Annotations like @RestController, @ResponseBody, @RequesBody
● RestTemplate
Spring Rest Support

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● Create stand-alone Spring applications
● Embed Tomcat, Jetty or Undertow directly (no need
to deploy WAR files)
● Easy Dependency Management & Automatically
configure Spring and 3rd party libraries whenever
possible
● Provide production-ready features such as metrics,
health checks and externalized configuration
Spring Boot features

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Auto Configuration

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JetBrains 2019
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JetBrains 2019
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EJB 3.0
EJB 3.0 & SOAP
EJB 2.0
SOAP

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Why bother write tests?

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1. It costs a lot
2. It’s boring
3. It’s working anyway
4. Don’t you test in production?
Why you shouldn’t write tests

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● Better than frequent fire in prod
● Profit for the team
● It’s YOUR problem
Why you !!should!! write tests

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Maintainability

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● Understanding of requirements
● Refactoring insurance
● Documenting features
● Improving API
● Reducing errors
● Confirming code is working on
review
Advantages to dev

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● Branch Pipelines
● Build Pipelines
● Deploy Pipelines
Testing Automation DevOps

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● You are not allowed to write any production code unless it is to make
a failing unit test pass.
● You are not allowed to write any more of a unit test than is sufficient to
fail; and compilation failures are failures.
● You are not allowed to write any more production code than is
sufficient to pass the one failing unit test.
The Three Laws of TDD

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Code first, no time to think

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Test Pyramid

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The goal of unit testing, is to validate that each unit of
the software performs as designed. A unit is the
smallest testable part of any software.
Goal of Unit Testing

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The goal of integration testing, is to test whether many
separately developed modules work together as
expected
Goal of Integration Testing

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● Give us confidence that the code does what it
should.
● Provide feedback that is fast, accurate, reliable and
predictable
● Make maintenance easier, something that is
commonly overlooked when writing tests.
As summary

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Spring Test Framework Overview

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● SpringRunner for jUnit 4
● @MockMVC & @WebMvcTest
● @RestClientTest & TestRestTemplate
● @ContextConfiguration & @WebAppConfiguration
● @DataJpaTest & @SpringBootTest
● @TestConfiguration
● @TestPropertySource
● @ActiveProfiles
● @ContextHierarchy
● @DirtiesContext
● @TestExecutionListeners
● JsonPath
● …..
Spring Test

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● @ContextConfiguration
● @WebAppConfiguration
● @TestConfiguration
● @ActiveProfiles
● @ContextHierarchy
● @TestPropertySource
● @DirtiesContext
Spring Test Configuration

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● @SpringBootTest
● @ActiveProfiles
● @TestPropertySource
● @Import
● @ContextConfiguration
Annotations which impact on context

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Once the TestContext framework loads an
ApplicationContext (or WebApplicationContext) for a
test, that context is cached and reused for all
subsequent tests that declare the same unique context
configuration within the same test suite.
Context Caching

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DEMO

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● Using profiles wisely
● Reconsidering usage of @MockBean
● Thinking carefully about @DirtiesContext
● Using test slices - @WebMvcTest & @DataJpaTest,
etc
● Using class inheritance
● Refactoring into unit tests
Spring Test Performance Optimization

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Usual test configuration with Spring Test

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Writing custom Spring test code feels like

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Reviewing Test Results

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● curl and http request snippets are generated
● easy to package documentation in projects jar file
● easy to add extra information to the snippets
● supports both JSON & XML
● keep up docs with your up-to-date functionality
● encourage to work by TDD
Spring Rest Docs

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Spring Rest Docs

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Allure

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DEMO

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One more thing

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● Spring Boot 1.x EOL Aug 1st 2019
● Time to upgrade
It is time - Goodbye Spring Boot 1.x!

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● https://mockaroo.com/
● https://github.com/Codearte/jfairy
● https://github.com/six2six/fixture-factory
● https://github.com/DiUS/java-faker
Test Data Fakers

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Final thought

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How it feels presenting after 2 Senior Consultants

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Q/A

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Q/A

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Thank you