Testing in Spring Boot

The Spring Boot test starter package is added to the pom.xml file by Spring Initializr when we create our project. This is added automatically without any selection in the Spring Initializr page. The code can be seen in the following snippet:

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
</dependency>

The Spring Boot test starter provides lots of handy libraries for testing, such as JUnit, Mockito, and AssertJ. In this book, we are using the JUnit 5 version (JUnit Jupiter). If you take a look, your project structure already has its own package created for test classes, as we can see in the following screenshot:

Figure 5.16 – Test classes

By default, Spring Boot uses an in-memory database for...