diff --git a/backend/src/controllers/submissions.ts b/backend/src/controllers/submissions.ts
index a117d7bf..012636ea 100644
--- a/backend/src/controllers/submissions.ts
+++ b/backend/src/controllers/submissions.ts
@@ -62,6 +62,11 @@ export async function getAllSubmissionsHandler(req: Request, res: Response): Pro
 
 // TODO: gerald moet nog dingen toevoegen aan de databank voor dat dit gefinaliseerd kan worden
 export async function createSubmissionHandler(req: Request, res: Response): Promise<void> {
+    const submitter = req.body.submitter;
+    const usernameSubmitter = req.body.submitter.username;
+    const group = req.body.group;
+    requireFields({ group, submitter, usernameSubmitter });
+
     const submissionDTO = req.body as SubmissionDTO;
     const submission = await createSubmission(submissionDTO);
 
diff --git a/backend/src/services/students.ts b/backend/src/services/students.ts
index 77ec6648..809b23e4 100644
--- a/backend/src/services/students.ts
+++ b/backend/src/services/students.ts
@@ -42,7 +42,7 @@ export async function fetchStudent(username: string): Promise<Student> {
     const user = await studentRepository.findByUsername(username);
 
     if (!user) {
-        throw new NotFoundException('Student with username not found');
+        throw new NotFoundException(`Student with username ${username} not found`);
     }
 
     return user;
diff --git a/backend/tests/controllers/assignments.test.ts b/backend/tests/controllers/assignments.test.ts
new file mode 100644
index 00000000..88cac366
--- /dev/null
+++ b/backend/tests/controllers/assignments.test.ts
@@ -0,0 +1,76 @@
+import { setupTestApp } from '../setup-tests.js';
+import { describe, it, expect, beforeAll, beforeEach, vi, Mock } from 'vitest';
+import { Request, Response } from 'express';
+import { getAssignmentHandler, getAllAssignmentsHandler, getAssignmentsSubmissionsHandler } from '../../src/controllers/assignments.js';
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+import { getClass01 } from '../test_assets/classes/classes.testdata';
+import { getAssignment01 } from '../test_assets/assignments/assignments.testdata';
+
+function createRequestObject(
+    classid: string,
+    assignmentid: string
+): {
+    query: { full: string };
+    params: { classid: string; id: string };
+} {
+    return {
+        params: {
+            classid: classid,
+            id: assignmentid,
+        },
+        query: {
+            full: 'true',
+        },
+    };
+}
+
+describe('Assignment controllers', () => {
+    let req: Partial<Request>;
+    let res: Partial<Response>;
+
+    let jsonMock: Mock;
+    let statusMock: Mock;
+
+    beforeAll(async () => {
+        await setupTestApp();
+    });
+
+    beforeEach(async () => {
+        jsonMock = vi.fn();
+        statusMock = vi.fn().mockReturnThis();
+
+        res = {
+            json: jsonMock,
+            status: statusMock,
+        };
+    });
+
+    it('return error non-existing assignment', async () => {
+        req = createRequestObject('doesnotexist', '43000'); // Should not exist
+
+        await expect(async () => getAssignmentHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('should return an assignment', async () => {
+        const assignment = getAssignment01();
+        req = createRequestObject(assignment.within.classId as string, (assignment.id ?? 1).toString());
+
+        await getAssignmentHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ assignment: expect.anything() }));
+    });
+
+    it('should return a list of assignments', async () => {
+        req = createRequestObject(getClass01().classId as string, 'irrelevant');
+
+        await getAllAssignmentsHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ assignments: expect.anything() }));
+    });
+
+    it('should return a list of submissions for an assignment', async () => {
+        const assignment = getAssignment01();
+        req = createRequestObject(assignment.within.classId as string, (assignment.id ?? 1).toString());
+
+        await getAssignmentsSubmissionsHandler(req as Request, res as Response);
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ submissions: expect.anything() }));
+    });
+});
diff --git a/backend/tests/controllers/classes.test.ts b/backend/tests/controllers/classes.test.ts
index ab941773..d9614a3b 100644
--- a/backend/tests/controllers/classes.test.ts
+++ b/backend/tests/controllers/classes.test.ts
@@ -1,8 +1,17 @@
 import { setupTestApp } from '../setup-tests.js';
 import { describe, it, expect, beforeAll, beforeEach, vi, Mock } from 'vitest';
+import {
+    createClassHandler,
+    deleteClassHandler,
+    getAllClassesHandler,
+    getClassHandler,
+    getClassStudentsHandler,
+    getTeacherInvitationsHandler,
+} from '../../src/controllers/classes.js';
 import { Request, Response } from 'express';
-import { createClassHandler, deleteClassHandler } from '../../src/controllers/classes';
-
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+import { BadRequestException } from '../../src/exceptions/bad-request-exception';
+import { getClass01 } from '../test_assets/classes/classes.testdata';
 describe('Class controllers', () => {
     let req: Partial<Request>;
     let res: Partial<Response>;
@@ -44,4 +53,71 @@ describe('Class controllers', () => {
 
         expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ class: expect.anything() }));
     });
+
+    it('Error class not found', async () => {
+        req = {
+            params: { id: 'doesnotexist' },
+        };
+
+        await expect(async () => getClassHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('Error create a class without name', async () => {
+        req = {
+            body: {},
+        };
+
+        await expect(async () => createClassHandler(req as Request, res as Response)).rejects.toThrow(BadRequestException);
+    });
+
+    it('return list of students', async () => {
+        req = {
+            params: { id: getClass01().classId as string },
+            query: {},
+        };
+
+        await getClassStudentsHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ students: expect.anything() }));
+    });
+
+    it('Error students on a non-existent class', async () => {
+        req = {
+            params: { id: 'doesnotexist' },
+            query: {},
+        };
+
+        await expect(async () => getClassStudentsHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('should return 200 and a list of teacher-invitations', async () => {
+        const classId = getClass01().classId as string;
+        req = {
+            params: { id: classId },
+            query: {},
+        };
+
+        await getTeacherInvitationsHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ invitations: expect.anything() }));
+    });
+
+    it('Error teacher-invitations on a non-existent class', async () => {
+        req = {
+            params: { id: 'doesnotexist' },
+            query: {},
+        };
+
+        await expect(async () => getTeacherInvitationsHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('should return a list of classes', async () => {
+        req = {
+            query: {},
+        };
+
+        await getAllClassesHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ classes: expect.anything() }));
+    });
 });
diff --git a/backend/tests/controllers/groups.test.ts b/backend/tests/controllers/groups.test.ts
new file mode 100644
index 00000000..f9e35cea
--- /dev/null
+++ b/backend/tests/controllers/groups.test.ts
@@ -0,0 +1,140 @@
+import { setupTestApp } from '../setup-tests.js';
+import { describe, it, expect, beforeAll, beforeEach, vi, Mock } from 'vitest';
+import { Request, Response } from 'express';
+import {
+    createGroupHandler,
+    deleteGroupHandler,
+    getAllGroupsHandler,
+    getGroupHandler,
+    getGroupSubmissionsHandler,
+} from '../../src/controllers/groups.js';
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+import { getClass01 } from '../test_assets/classes/classes.testdata';
+import { getAssignment01, getAssignment02 } from '../test_assets/assignments/assignments.testdata';
+import { getTestGroup01 } from '../test_assets/assignments/groups.testdata';
+
+function createRequestObject(
+    classid: string,
+    assignmentid: string,
+    groupNumber: string
+): {
+    query: { full: string };
+    params: { classid: string; groupid: string; assignmentid: string };
+} {
+    return {
+        params: {
+            classid: classid,
+            assignmentid: assignmentid,
+            groupid: groupNumber,
+        },
+        query: {
+            full: 'true',
+        },
+    };
+}
+
+describe('Group controllers', () => {
+    let req: Partial<Request>;
+    let res: Partial<Response>;
+
+    let jsonMock: Mock;
+    let statusMock: Mock;
+
+    beforeAll(async () => {
+        await setupTestApp();
+    });
+
+    beforeEach(async () => {
+        jsonMock = vi.fn();
+        statusMock = vi.fn().mockReturnThis();
+
+        res = {
+            json: jsonMock,
+            status: statusMock,
+        };
+    });
+
+    it('Error not found on a non-existing group', async () => {
+        req = {
+            params: {
+                classid: 'id01',
+                assignmentid: '1',
+                groupid: '154981', // Should not exist
+            },
+            query: {},
+        };
+
+        await expect(async () => getGroupHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('should return 404 not found on a non-existing assignment', async () => {
+        req = {
+            params: {
+                classid: 'id01',
+                assignmentid: '1000', // Should not exist
+                groupid: '42000', // Should not exist
+            },
+            query: {},
+        };
+
+        await expect(async () => getGroupHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('should return 404 not found ont a non-existing class', async () => {
+        req = {
+            params: {
+                classid: 'doesnotexist', // Should not exist
+                assignmentid: '1000', // Should not exist
+                groupid: '42000', // Should not exist
+            },
+            query: {},
+        };
+
+        await expect(async () => getGroupHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('should return an existing group', async () => {
+        const group = getTestGroup01();
+        const classId = getClass01().classId as string;
+        req = createRequestObject(classId, (group.assignment.id ?? 1).toString(), (group.groupNumber ?? 1).toString());
+
+        await getGroupHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ group: expect.anything() }));
+    });
+
+    it('Create and delete', async () => {
+        const assignment = getAssignment02();
+        const classId = assignment.within.classId as string;
+        req = createRequestObject(classId, (assignment.id ?? 1).toString(), '1');
+        req.body = {
+            members: ['Noordkaap', 'DireStraits'],
+        };
+
+        await createGroupHandler(req as Request, res as Response);
+
+        await deleteGroupHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ group: expect.anything() }));
+    });
+
+    it('should return the submissions for a group', async () => {
+        const group = getTestGroup01();
+        const classId = getClass01().classId as string;
+        req = createRequestObject(classId, (group.assignment.id ?? 1).toString(), (group.groupNumber ?? 1).toString());
+
+        await getGroupSubmissionsHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ submissions: expect.anything() }));
+    });
+
+    it('should return a list of groups for an assignment', async () => {
+        const assignment = getAssignment01();
+        const classId = assignment.within.classId as string;
+        req = createRequestObject(classId, (assignment.id ?? 1).toString(), '1');
+
+        await getAllGroupsHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ groups: expect.anything() }));
+    });
+});
diff --git a/backend/tests/controllers/submissions.test.ts b/backend/tests/controllers/submissions.test.ts
new file mode 100644
index 00000000..942b51f8
--- /dev/null
+++ b/backend/tests/controllers/submissions.test.ts
@@ -0,0 +1,61 @@
+import { setupTestApp } from '../setup-tests.js';
+import { describe, it, expect, beforeAll, beforeEach, vi, Mock } from 'vitest';
+import { getSubmissionHandler, getAllSubmissionsHandler } from '../../src/controllers/submissions.js';
+import { Request, Response } from 'express';
+import { NotFoundException } from '../../src/exceptions/not-found-exception';
+import { getClass02 } from '../test_assets/classes/classes.testdata';
+
+function createRequestObject(
+    hruid: string,
+    submissionNumber: string
+): {
+    query: { language: string; version: string };
+    params: { hruid: string; id: string };
+} {
+    return {
+        params: {
+            hruid: hruid,
+            id: submissionNumber,
+        },
+        query: {
+            language: 'en',
+            version: '1',
+        },
+    };
+}
+
+describe('Submission controllers', () => {
+    let req: Partial<Request>;
+    let res: Partial<Response>;
+
+    let jsonMock: Mock;
+    let statusMock: Mock;
+
+    beforeAll(async () => {
+        await setupTestApp();
+    });
+
+    beforeEach(async () => {
+        jsonMock = vi.fn();
+        statusMock = vi.fn().mockReturnThis();
+
+        res = {
+            json: jsonMock,
+            status: statusMock,
+        };
+    });
+
+    it('error submission is not found', async () => {
+        req = createRequestObject('id01', '1000000');
+
+        await expect(async () => getSubmissionHandler(req as Request, res as Response)).rejects.toThrow(NotFoundException);
+    });
+
+    it('should return a list of submissions for a learning object', async () => {
+        req = createRequestObject(getClass02().classId as string, 'irrelevant');
+
+        await getAllSubmissionsHandler(req as Request, res as Response);
+
+        expect(jsonMock).toHaveBeenCalledWith(expect.objectContaining({ submissions: expect.anything() }));
+    });
+});