Spring Boot Testing: exception in REST controller - spring

Question

I have a Spring Boot application and want to cover my REST controllers by integration test.
Here is my controller:
#RestController
#RequestMapping("/tools/port-scan")
public class PortScanController {
private final PortScanService service;
public PortScanController(final PortScanService portScanService) {
service = portScanService;
}
#GetMapping("")
public final PortScanInfo getInfo(
#RequestParam("address") final String address,
#RequestParam(name = "port") final int port)
throws InetAddressException, IOException {
return service.scanPort(address, port);
}
}
In one of test cases I want to test that endpoint throws an exception in some circumstances. Here is my test class:
#RunWith(SpringRunner.class)
#WebMvcTest(PortScanController.class)
public class PortScanControllerIT {
#Autowired
private MockMvc mvc;
private static final String PORT_SCAN_URL = "/tools/port-scan";
#Test
public void testLocalAddress() throws Exception {
mvc.perform(get(PORT_SCAN_URL).param("address", "192.168.1.100").param("port", "53")).andExpect(status().isInternalServerError());
}
}
What is the best way to do that? Current implementation doesn't handle InetAddressException which is thrown from PortScanController.getInfo() and when I start test, I receive and error:
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is com.handytools.webapi.exceptions.InetAddressException: Site local IP is not supported
It is not possible to specify expected exception in #Test annotation since original InetAddressException is wrapped with NestedServletException.

Answer 1

Spring Boot Test package comes with AssertJ that has very convenient way of verifying thrown exceptions.
To verify cause:
#Test
public void shouldThrowException() {
assertThatThrownBy(() -> methodThrowingException()).hasCause(InetAddressException .class);
}
There are also few more methods that you may be interested in. I suggest having a look in docs.

Answer 2

In order to test the wrapped exception (i.e., InetAddressException), you can create a JUnit Rule using ExpectedException class and then set the expectMessage() (received from NestedServletException's getMessage(), which contains the actual cause), you can refer the below code for the same:
#Rule
public ExpectedException inetAddressExceptionRule = ExpectedException.none();
#Test
public void testLocalAddress() {
//Set the message exactly as returned by NestedServletException
inetAddressExceptionRule.expectMessage("Request processing failed; nested exception is com.handytools.webapi.exceptions.InetAddressException: Site local IP is not supported");
//or you can check below for actual cause
inetAddressExceptionRule.expectCause(org.hamcrest.Matchers.any(InetAddressException.class))
//code for throwing InetAddressException here (wrapped by Spring's NestedServletException)
}
You can refer the ExpectedException API here:
http://junit.org/junit4/javadoc/4.12/org/junit/rules/ExpectedException.html

Answer 3

You could define an exception handler
#ExceptionHandler(InetAddressException.class)
#ResponseStatus(HttpStatus.BAD_REQUEST)
#ResponseBody
public Response handledInvalidAddressException(InetAddressException e)
{
log e
return getValidationErrorResponse(e);
}
and then in your test you could do
mvc.perform(get(PORT_SCAN_URL)
.param("address", "192.168.1.100")
.param("port", "53"))
.andExpect(status().isBadRequest())
.andExpect(jsonPath("$.response").exists())
.andExpect(jsonPath("$.response.code", is(400)))
.andExpect(jsonPath("$.response.errors[0].message", is("Site local IP is not supported")));

Answer 4

I had the same issue and i fix it with org.assertj.core.api.Assertions.assertThatExceptionOfType :
#Test
public void shouldThrowInetAddressException() {
assertThatExceptionOfType(InetAddressException.class)
.isThrownBy(() -> get(PORT_SCAN_URL).param("address", "192.168.1.100").param("port", "53"));
}
I hope it's help you !