Unable to Mock the Database call handled by Spring JPA framework while writing test Case for Controller Class - spring-mvc

Question

Spring MVC converts the id from path to corresponding object by making call to JpaRepository's findById method. For example see getVersionTree() method.
public class Controller {
#NonNull
private final MyService service;
#NonNull
private final MyAssembler assembler;
#GetMapping(path = VERSION_TREE_MAPPING, produces = MediaTypes.HAL_JSON_UTF8_VALUE)
public HttpEntity<?> getVersionTree(#PathVariable("id") MappingDocument mappingDocument, Pageable pageable, PagedResourcesAssembler<VersionNode> pagedResourcesAssembler) {
Page<VersionNode> versionNodes = service.getVersionTreeFor(mappingDocument, pageable);
return new ResponseEntity<>(pagedResources, HttpStatus.OK);
}
While testing, SpringMVC throws " Failed to convert value of type 'java.lang.String' to required type 'com.rbc.dna.dtl.mappingdocument.MappingDocument'". I am mocking jpaRepository.findById() method. Test Code is as follows:
#Autowired
private WebApplicationContext webApplicationContext;
#MockBean
private MyRepository repository;
#Mock
MyController controller;
#MockBean
private MyServiceImpl serviceImpl;
#Test
public void testMethod() throws Exception {
MockMvc mockMvc = MockMvcBuilders.webAppContextSetup(webApplicationContext).apply(SecurityMockMvcConfigurers.springSecurity()).build();
MappingDocument mappingDocumentl=MappingDocument.builder().id(17L).build();
Mockito.when(repository.findById(17L)).thenReturn(Optional.of(mappingDocumentl));
Mockito.when(serviceImpl.getVersionTreeFor(mappingDocument,pageable)).thenReturn(pagedResponse);
mockMvc.perform(MockMvcRequestBuilders.get("/abc/17/def").param("page","0").param("size","20").contentType(MediaTypes.HAL_JSON_UTF8_VALUE)
.with(authentication(getOauthTestAuthentication()))
.sessionAttr("scopedTarget.oauth2ClientContext", getOauth2ClientContext()))
.andExpect(MockMvcResultMatchers.status().isOk()) .andExpect(MockMvcResultMatchers.status().isOk())
.andDo(MockMvcResultHandlers.print());
}

Answer 1

Your rest Controller take #PathVariable("id") MappingDocument mappingDocument as variable in your path, but in mockMvc.perform you are passing a simple String/Number or something that doesn't bind with MappingDocument.
Try to replace
public HttpEntity<?> getVersionTree(#PathVariable("id") MappingDocument mappingDocument...
with
public HttpEntity<?> getVersionTree(#PathVariable("id") Long idMappingDocument, ...
If you want to keep your object in #PathVariable you need to change
#GetMapping(path = VERSION_TREE_MAPPING)
To parse an object as PathVariable you need to have path that represent property of your object.
For example if you have
class Person {
String name;
String address;
//getters and setters
}
and you need to define a controller as follow:
#GetMapping(path = "/person/{name}/{address}", produces = MediaTypes.HAL_JSON_UTF8_VALUE)
public HttpEntity<?> getVersionTree(Person person) {
Where {name} and {address} must bind Person properties