Example of runnable spring boot application based on Spring in Action 4
Launch main in com.example.Application.class and check localhost:8085
Hamcrest
R1-Unit Test guide https://howtodoinjava.com/spring-boot2/testing/spring-boot-mockmvc-example/ https://www.baeldung.com/spring-boot-testing https://ithelp.ithome.com.tw/articles/10196471 https://spring.io/guides/gs/testing-web/ https://howtodoinjava.com/spring-boot2/testing/springboottest-annotation/
Q1-spring boot java.net.BindException: Address already in use
A1-Change your application server port, for that create a file named application.properties in resource folder and add property
server.port = 8085
Q2-Unable to find a @SpringBootConfiguration
A2-Need to specify the application class Ex:@SpringBootTest(classes = com.example.Application.class)
https://stackoverflow.com/questions/39084491/unable-to-find-a-springbootconfiguration-when-doing-a-jpatest
Q3-Error processing condition on org.springframework.boot.autoconfigure.thymeleaf.ThymeleafAutoConfiguration$ThymeleafWebMvcConfiguration.resourceUrlEncodingFilter
A3-This is caused by non-matching Spring Boot dependencies.
Use spring-boot-starter-thymeleaf instead of org.thymeleaf
Q4-MockRepository encounter MissingMethodInvocationException
Add @Mock to MockRespoitory
@Mock creates a mock.
@InjectMocks creates an instance of the class and injects the mocks that are created with the @Mock (or @Spy) annotations into this instance.
Note that you must use @RunWith(MockitoJUnitRunner.class) or Mockito.initMocks(this) to initialize these mocks and inject them.
https://stackoverflow.com/questions/16467685/difference-between-mock-and-injectmocks
Q5-What is @AutoConfigureWebMvc and @AutoConfigureMockMvc
@AutoConfigureWebMvc
Use this if you need to configure the web layer for testing but don't need to use MockMvc
It enables all auto-configuration related to the web layer and ONLY the web layer. This is a subset of overall auto-configuration.
@AutoConfigureMockMvc
Use this when you just want to configure MockMvc
Enables all auto-configuration related to MockMvc and ONLY MockMvc. Again, this is a subset of overall auto-configuration.
@WebMvcTest
Includes both the @AutoConfigureWebMvc and the @AutoConfigureMockMvc, among other functionality.
https://stackoverflow.com/questions/46343782/whats-the-difference-between-autoconfigurewebmvc-and-autoconfiguremockmvc
Q6-Difference between @RunWith(SpringRunner.class) and @RunWith(SpringJUnit4ClassRunner.class)
There is no difference, from the javadoc:
SpringRunner is an alias for the SpringJUnit4ClassRunner.
https://stackoverflow.com/questions/47446529/what-is-the-difference-between-springjunit4classrunner-and-springrunner
Q7-How to write com.example.unit test on controller?
https://howtodoinjava.com/spring-boot2/testing/rest-controller-com.example.unit-test-example/
While writing junit test for a rest controller method, we shall keep in mind that:
A com.example.unit test is supposed to test only a certain part of code (i.e. code written in controller class), so we shall mock all the dependencies injected and used in controller class.
If the test utilizes other dependencies (e.g. database/network) then it is integration testing and not com.example.unit testing.
We should not use any webserver otherwise it will make the com.example.unit testing slow.
Each com.example.unit test should be independent of other tests.
By definition, com.example.unit tests should be fast.
Q8-detached entity passed to persist exception. One reason for this case is setting a auto generate value during unit test.