Spring Integration - How to mock input-channel - junit

Question

I am new to Spring Integration so please forgive and correct me if my question is absurd. I am trying to write Unit test cases for Spring Integration application where I am testing only controller and looking to mock service call.
Test:
#RunWith(PowerMockRunner.class)
#PrepareForTest({HeaderUtils.class})
#PowerMockIgnore({ "javax.management.*", "javax.script.*" })
public class DocMgmtImplTestPower {
private MockMvc mvc;
#InjectMocks
private DocMgmtImpl docMgmtImpl;
#Mock
DocMgmtService docMgmtServiceGateway;
#Mock
SendComnMsgResponse sendComnMsgResponse;
#Before
public void init() {
MockitoAnnotations.initMocks(this); //
mvc = MockMvcBuilders.standaloneSetup(DocMgmtImpl.class).build();
PowerMockito.mockStatic(HeaderUtils.class, new Answer<Map<String, Object>>() {
#Override
public Map<String, Object> answer(InvocationOnMock arg0) throws Throwable {
Map<String, Object> headers = new HashMap<String, Object>();
HeaderInfo headerInfo = new HeaderInfo();
headers.put(BusinessServiceConstants.SERVICE_HEADER, headerInfo);
return headers;
}
});
}
#SuppressWarnings("deprecation")
#Test
public void testMethod() throws Exception {
SpecialFormMsgRequest arg = new SpecialFormMsgRequest();
Map<String, Object> headers = new HashMap<String, Object>();
Mockito.when(docMgmtServiceGateway.specialFormMsg(Mockito.any(SpecialFormMsgRequest.class),
(Matchers.<Map<String, Object>>any()))).thenReturn(new SendComnMsgResponse());
SpecialFormMsgRequest msg = new SpecialFormMsgRequest();
msg.setUiStaticDocFlag("N");
mvc.perform(post("/specialMsg").accept(MediaType.APPLICATION_JSON).content(asJsonString(msg))
.contentType(MediaType.APPLICATION_JSON)).andDo(print()).andExpect(status().isOk());
}
public static String asJsonString(final Object obj) {
try {
return new ObjectMapper().writeValueAsString(obj);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}
Controller:
#Controller
public class DocMgmtImpl implements DocMgmt {
#Autowired
**DocMgmtService docMgmtServiceGateway;** **// I want to mock this service.**
#Override
#RequestMapping(value = "/specialMsg", method = RequestMethod.POST)
#ResponseBody
public SendComnMsgResponse specialMsg(#Valid #RequestBody final SpecialFormMsgRequest specialFormMsgRequest)
throws BusinessException, TechnicalException {
SendComnMsgResponse sendComnMsgResponse = null;
try {
Map<String, Object> headers = HeaderUtils.getHeaders(poBusinessHeader); // PowerMockito working here...
sendComnMsgResponse = **this.docMgmtServiceGateway.specialFormMsg(specialFormMsgRequest, headers);** // docMgmtServiceGateway is getting null...
} catch (Exception exception) {
handleException(exception);
}
return sendComnMsgResponse;
}
}
Gateway.xml:
<int:gateway id="docMgmtServiceGateway" service-interface="group.doc.svc.gateway.DocMgmtService"
default-reply-channel="docReplyChannel" error-channel="docErrorChannel">
<int:method name="sendComnMsg" request-channel="sendComnMsgRequestChannel" />
</int:gateway>
si-chain.xml:
<int:chain input-channel="esDBBISendComnMsgRequestChannel" output-channel="docReplyChannel">
<int:transformer method="formatRequest" ref="esSendComnMsgTransformer"/>
<int:service-activator ref="sendComnMsgActivator" method="sendComnMsg" />
<int:transformer method="parseResponse" ref="esSendComnMsgTransformer"/>
</int:chain>
I am wondering, whether I am doing correct or not. Because DocMgmtService service is an interface and it don't have implementation. After controller call goes to Transformer as configured above. On this setup I have following quetions.
Can I mock DocMgmtService service with same setup if not what will be correct approach.
If yes then how can I mock my service.
Thanks

Answer 1

It depends on exactly what you want to test.
If you mock the interface, all you are testing is your mock stubbing for that interface (pointless).
The framework creates an implementation of the interface which creates a message from the parameters and sends it to the channel.
You should auto wire the gateway into your test and call it.
You can mock any of the downstream components (e.g. sendComnMsgActivator) as needed.