test: student repository is getest

backend/tests/data/students.test.ts

@@ -0,0 +1,51 @@
+import { setupTestApp } from '../setup-tests.js';
+import { Student } from '../../src/entities/users/student.entity.js';
+import { describe, it, expect, beforeAll } from 'vitest';
+import { StudentRepository } from '../../src/data/users/student-repository.js';
+import { getStudentRepository } from '../../src/data/repositories.js';
+
+const username = 'teststudent';
+const firstName = 'John';
+const lastName = 'Doe';
+describe('StudentRepository', () => {
+    let studentRepository: StudentRepository;
+
+    beforeAll(async () => {
+        await setupTestApp();
+        studentRepository = getStudentRepository();
+    });
+
+    it('should not return a student because username does not exist', async() => {
+        const student = await studentRepository.findByUsername('test');
+
+        expect(student).toBeNull();
+    });
+
+    it('should return student from the datbase', async() => {
+        const student = await studentRepository.findByUsername('DireStraits');
+
+        expect(student).toBeTruthy();
+        expect(student?.firstName).toBe('Mark');
+        expect(student?.lastName).toBe('Knopfler');
+    })
+
+    it('should return the queried student after he was added', async () => {
+        await studentRepository.insert(
+            new Student(username, firstName, lastName)
+        );
+
+        const retrievedStudent =
+            await studentRepository.findByUsername(username);
+        expect(retrievedStudent).toBeTruthy();
+        expect(retrievedStudent?.firstName).toBe(firstName);
+        expect(retrievedStudent?.lastName).toBe(lastName);
+    });
+
+    it('should no longer return the queried student after he was removed again', async () => {
+        await studentRepository.deleteByUsername(username);
+
+        const retrievedStudent =
+            await studentRepository.findByUsername(username);
+        expect(retrievedStudent).toBeNull();
+    });
+});