WebMvcTest is too greedy - spring

Question

I want to write a WebMvcTest test for a single controller in my Spring Boot application. Among other things there are some custom Converters in my application. Although they are not needed for this particular controller that I want to test, Spring tries to create them anyway.
Now the problem: those custom converters require more beans from my application which are not initialised by WebMvcTest test slice. And don't want to mock tens of beans which are completely irrelevant for the particular test. Apart from specifying them all manually in excludeFilters, what are best practises for excluding some web components from specific WebMvcTest tests?

Answer 1

You could use a custom exclude filter in order to avoid loading converters into application context:
#RunWith(SpringRunner.class)
#WebMvcTest(controllers = YourController.class, excludeFilters = #ComponentScan.Filter(type = CUSTOM, classes = NoConvertersFilter.class))
public class YourControllerTest {
...
}
class NoConvertersFilter extends TypeExcludeFilter {
private static final String CONVERTER_INTERFACE_NAME = Converter.class.getName();
#Override
public boolean match(#NonNull final MetadataReader metadataReader, #NonNull final MetadataReaderFactory metadataReaderFactory) throws IOException {
return Arrays.asList(metadataReader.getClassMetadata().getInterfaceNames()).contains(CONVERTER_INTERFACE_NAME);
}
}
With this approach you just have to add the excludeFilter to those controllers in which you don't want to have Converters loaded. No worries if a new converter is added: it'll be automatically excluded as far as it implements the converter interface.

Answer 2

For custom tests don't use WebMvcTest, create a custom configuration:
#SpringBootTest
#WebAppConfiguration
#RunWith(value = SpringJUnit4ClassRunner.class)
#ContextConfiguration(classes = {SomeYourTestConfiguration.class})
public class TestClass {
private MockMvc mockMvc;
#Before
public void setup() {
var someController = new SomeController();
mockMvc = MockMvcBuilders.standaloneSetup(someController).addFilters(...)
.setMessageConverters(...).setControllerAdvice(...).setValidator(...);
}
#Test
public void test() {
//arrange
when(...).thenReturn(...);
//act
var response = mockMvc.perform(...).andReturn().getResponse();
//assert
...
}
}
You can configure your mockMvc how you want.