Is there a way to include a spring component in a WebMvcTest - spring-boot

Question

Given production code classes:
#RestController
#RequiredArgsConstructor
public class MyController {
private final MyValidator validator;
// annotations relating to request mapping excluded for brevity
public void test(#Valid #RequestBody final MyParams params) {
// do stuff
}
#InitBinder
#SuppressWarnings("unused")
protected void initBinder(final WebDataBinder binder) {
binder.setValidator(validator);
}
}
and
#Component
#RequiredArgsConstructor
public class MyValidator implements Validator {
...
#Override
public void validate(final Object target, final Errors errors) {
// custom validation
}
}
and finally test code:
#RunWith(SpringRunner.class)
#WebMvcTest(MyController.class)
public class MyControllerTest {
// tests
}
I encounter the error:
NoSuchBeanDefinitionException: No qualifying bean of type 'MyValidator' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
I think the error is fair enough. I've annotated the test as a WebMvcTest, which I believe has excluded #Component beans. This is intentional and desired (from the perspective that I am only wanting to test the "web layer", not the whole context - it just so happens I need a component which is related/used only in the controllers)
My question, therefore, is: how can one explicitly include a component like a validator in the test context for a web test?
My environment is java version "10.0.2" 2018-07-17, spring boot 1.5.16.RELEASE.

Answer 1

There are two ways to solve this.
Using #SpringBootTest and #AutoConfigureMvc instead of #RunWith(SpringRunner.class) and #WebMvcTest.
#SpringBootTest
#AutoConfigureMvc
public class MyControllerTest {
}
Creating a #TestConfiguration class that injects the 'MyValidator' bean as:
#RunWith(SpringRunner.class)
#WebMvcTest(MyController.class)
public class MyControllerTest {
#TestConfiguration
static class TestConfig {
#Bean
MyValidator getMyValidator(){
return new MyValidator();
}
}
// tests
}
More on this can be found here : https://mkyong.com/spring-boot/spring-boot-how-to-init-a-bean-for-testing/

Answer 2

There are two ways to test the web layer
first.
#RunWith(SpringRunner.class)
#SpringBootTest
public class MyControllerTest {
#Autowired
private MyController myController;
}
The #SpringBootTest annotation tells Spring Boot to go and look for a
main configuration class (one with #SpringBootApplication for
instance), and use that to start a Spring application context.
A nice feature of the Spring Test support is that the application
context is cached in between tests, so if you have multiple methods in
a test case, or multiple test cases with the same configuration, they
only incur the cost of starting the application once. You can control
the cache using the #DirtiesContext annotation.
Secondly, if you want to use the #WebMvcTest(MyController.class)
#RunWith(SpringRunner.class)
#WebMvcTest(MyController.class)
public class MyControllerTest {
#MockBean
private MyValidator validator;
}
But this validator is a fake, so you have to customize it for testing.
See this link for more details https://spring.io/guides/gs/testing-web/

Answer 3

I cannot recommend it as a standard practice but if you do need an instance of a dependency in your Web MVC tests (for example in legacy code) you can add them into the spring context using #SpyBean annotation.
Real methods of that class will be called during the test and you can verify them if needed similarly to the beans annotated with #MockBean
#RunWith(SpringRunner.class)
#WebMvcTest(MyController.class)
public class MyControllerTest {
#SpyBean
private MyValidator validator
}