Added unit tests for GroupService

src/test/java/ntnu/idatt2016/v233/SmartMat/service/group/GroupServiceTest.java

+package ntnu.idatt2016.v233.SmartMat.service.group;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.util.Collections;
+import java.util.Optional;
+
+import ntnu.idatt2016.v233.SmartMat.entity.group.Group;
+import ntnu.idatt2016.v233.SmartMat.repository.group.GroupRepository;
+import ntnu.idatt2016.v233.SmartMat.util.GroupUtil;
+
+import static org.mockito.Mockito.*;
+import static org.junit.jupiter.api.Assertions.*;
+
+class GroupServiceTest {
+
+    @InjectMocks
+    private GroupService groupService;
+
+    @Mock
+    private GroupRepository groupRepository;
+
+    @BeforeEach
+    void setUp() {
+        MockitoAnnotations.openMocks(this);
+    }
+
+    @Test
+    void testGetGroupByName() {
+        String groupName = "Test Group";
+        Group group = new Group();
+        group.setGroupName(groupName);
+
+        when(groupRepository.findByGroupName(groupName)).thenReturn(Optional.of(group));
+
+        Optional<Group> result = groupService.getGroupByName(groupName);
+
+        assertTrue(result.isPresent());
+        assertEquals(groupName, result.get().getGroupName());
+    }
+
+    @Test
+    void testGetGroupById() {
+        long groupId = 1L;
+        Group group = new Group();
+        group.setGroupId(groupId);
+
+        when(groupRepository.findById(groupId)).thenReturn(Optional.of(group));
+
+        Optional<Group> result = groupService.getGroupById(groupId);
+
+        assertTrue(result.isPresent());
+        assertEquals(groupId, result.get().getGroupId());
+    }
+
+    @Test
+    void testCreateGroup() {
+        String groupName = "New Group";
+        Group group = new Group();
+        group.setGroupName(groupName);
+
+        when(groupRepository.findByGroupName(groupName)).thenReturn(Optional.empty());
+        when(groupRepository.findAllLinkCode()).thenReturn(Collections.emptyList());
+        when(groupRepository.save(any(Group.class))).thenAnswer(invocation -> invocation.getArgument(0));
+
+        Group createdGroup = groupService.createGroup(group);
+
+        assertEquals(groupName, createdGroup.getGroupName());
+        assertNotNull(createdGroup.getLinkCode());
+    }
+
+    @Test
+    void testGetLevelByGroupId() {
+        long groupId = 1L;
+        long level = 3L;
+        Group group = new Group();
+        group.setGroupId(groupId);
+        group.setLevel(level);
+
+        when(groupRepository.findById(groupId)).thenReturn(Optional.of(group));
+        when(groupRepository.getLevelByGroupId(groupId)).thenReturn(Optional.of(level));
+
+        Optional<Long> result = groupService.getLevelByGroupId(groupId);
+
+        assertTrue(result.isPresent());
+        assertEquals(level, result.get());
+    }
+}