Change the get by person and module to return one

Only one group can exist for a specific Person/Module combination,
therefore we should return only one group from this endpoint.

src/main/java/nl/tudelft/labracore/controller/StudentGroupController.java

@@ -26,6 +26,7 @@ import nl.tudelft.labracore.dto.helper.GroupGenerateDTO;
 import nl.tudelft.labracore.dto.patch.StudentGroupPatchDTO;
 import nl.tudelft.labracore.dto.view.other.StudentGroupShortDetailsDTO;
 import nl.tudelft.labracore.dto.view.other.StudentGroupSummaryDTO;
+import nl.tudelft.labracore.dto.view.structured.details.StudentGroupDetailsDTO;
 import nl.tudelft.labracore.dto.view.structured.summary.RoleSummaryDTO;
 import nl.tudelft.labracore.repository.StudentGroupRepository;
 import nl.tudelft.labracore.service.RoleService;
@@ -278,10 +279,10 @@ public class StudentGroupController {
 	 */
 	@GetMapping("/by-person-and-module/{personId}/{moduleId}")
 	@PreAuthorize("hasAuthority('STUDENT_GROUP_READ')")
-	public List<StudentGroupSummaryDTO> getGroupsForPersonAndModule(@PathVariable Long personId,
+	public StudentGroupDetailsDTO getGroupsForPersonAndModule(@PathVariable Long personId,
 			@PathVariable Long moduleId) {
-		return View.convert(sgr.findAllByModuleAndPersonIn(personId, moduleId),
-				StudentGroupSummaryDTO.class);
+		return View.convert(sgr.findByModuleAndPersonIn(personId, moduleId),
+				StudentGroupDetailsDTO.class);
 	}
 
 }

src/main/java/nl/tudelft/labracore/repository/StudentGroupRepository.java

@@ -98,12 +98,14 @@ public interface StudentGroupRepository
 	/**
 	 * @param  personId The id of the person to lookup.
 	 * @param  moduleId The id of the module to lookup.
-	 * @return          All groups that contain the given person in the given module.
+	 * @return          The group that contains the given person in the given module.
 	 */
-	default List<StudentGroup> findAllByModuleAndPersonIn(Long personId, Long moduleId) {
+	default StudentGroup findByModuleAndPersonIn(Long personId, Long moduleId) {
 		BooleanExpression q = studentGroup.module.id.eq(moduleId).and(
 				studentGroup.members.any().id.personId.eq(personId));
-		return findAll(q);
+		return findOne(q)
+				.orElseThrow(() -> new ResourceNotFoundException(
+						"StudentGroup was not found for person, module: " + personId + ", " + moduleId));
 	}
 
 }

src/test/java/nl/tudelft/labracore/controller/StudentGroupControllerIntegrationTest.java

@@ -33,6 +33,7 @@ import nl.tudelft.labracore.dto.create.StudentGroupCreateDTO;
 import nl.tudelft.labracore.dto.helper.GroupGenerateDTO;
 import nl.tudelft.labracore.dto.patch.StudentGroupPatchDTO;
 import nl.tudelft.labracore.dto.view.other.StudentGroupSummaryDTO;
+import nl.tudelft.labracore.dto.view.structured.details.StudentGroupDetailsDTO;
 import nl.tudelft.labracore.model.Course;
 import nl.tudelft.labracore.model.Person;
 import nl.tudelft.labracore.model.StudentGroup;
@@ -173,13 +174,12 @@ class StudentGroupControllerIntegrationTest extends RestControllerTest {
 
 	@Test
 	@WithUserDetails("All-access Key")
-	void getGroupsForPersonAndModuleWorks() throws Exception {
+	void getGroupForPersonAndModuleWorks() throws Exception {
 		mockMvc.perform(
 				get("/api/studentGroup/by-person-and-module/{p}/{m}", p.getId(), sg1.getModule().getId()))
 				.andExpect(status().isOk())
-				.andExpect(jsonContent(StudentGroupSummaryList.class)
-						.test(l -> assertThat(l).containsExactlyInAnyOrder(
-								View.convert(sg1, StudentGroupSummaryDTO.class))));
+				.andExpect(jsonContent(StudentGroupDetailsDTO.class)
+						.isEqualTo(View.convert(sg1, StudentGroupDetailsDTO.class)));
 	}
 
 	@WithUserDetails("No-access Key")