Important Tools and LIBRARIES for testing Spring-based Microservices are - 

• JUnit 

the standard test runners 

• TestNG 

the next generation test runner 

• Hemcrest 

declarative MATCHERS and assertions 

• Rest-assured 

for writing REST Api DRIVEN end to end tests 

• Mockito 

for mocking dependencies 

• Wiremock 

for stubbing thirdparty services 

• Hoverfly 

Create API simulation for end-to-end tests. 

• Spring Test and Spring BOOT Test 

for writing Spring Integration Tests - includes MockMVC, TestRestTemplate, Webclient like features. 

• JSONassert 

An assertion library for JSON. 

• Pact 

The Pact family of FRAMEWORKS provide support for Consumer Driven Contracts testing. 

• Selenium 

Selenium automates browsers. Its used for end-to-end automated ui testing. 

• Gradle 

Gradle helps build, automate and deliver software, fastr. 

• IntelliJ IDEA 

IDE for Java Development 

• Using spring-boot-starter-test 
  • We can just add the below dependency in project’s build.gradle 
  • testCompile('org.springframework.boot:spring-boot-starter-test')

This starter will import two spring boot test modules spring-boot-test & spring-boot-test- autoconfigure as well as Junit, AssertJ, Hamcrest, Mockito, JSONassert, Spring Test, Spring Boot Test and a number of other useful libraries.