test: harden business boundary conditions

apps/server/src/classes/classes.service.ts

@@ -286,6 +286,7 @@ export class ClassesService {
   async archive(id: number) {
     const cls = await this.classRepo.findOne({ where: { id } });
     if (!cls) throw new NotFoundException('班级不存在');
+    if (cls.isArchived) throw new BadRequestException('班级已归档');
     await this.classRepo.update(id, { isArchived: true });
     return { success: true };
   }
@@ -294,6 +295,7 @@ export class ClassesService {
   async restore(id: number) {
     const cls = await this.classRepo.findOne({ where: { id } });
     if (!cls) throw new NotFoundException('班级不存在');
+    if (!cls.isArchived) throw new BadRequestException('班级未归档');
     await this.classRepo.update(id, { isArchived: false });
     return { success: true };
   }
@@ -392,6 +394,9 @@ export class ClassesService {
   }
 
   async addTeacher(classId: number, dto: AddTeacherDto) {
+    const cls = await this.classRepo.findOne({ where: { id: classId } });
+    if (!cls) throw new NotFoundException('班级不存在');
+
     const existing = await this.classTeacherRepo.findOne({
       where: { classId, userId: dto.userId, roleType: dto.roleType },
     });
@@ -410,12 +415,18 @@ export class ClassesService {
   }
 
   async removeTeacher(classId: number, userId: number) {
+    const assignments = await this.classTeacherRepo.find({ where: { classId, userId } });
+    if (assignments.length === 0) throw new NotFoundException('教师未分配到该班级');
     await this.classTeacherRepo.delete({ classId, userId });
     await this.syncClassTeacherIds(classId);
     return { success: true };
   }
 
   async removeTeacherAssignment(classId: number, assignmentId: number) {
+    const assignment = await this.classTeacherRepo.findOne({
+      where: { id: assignmentId, classId },
+    });
+    if (!assignment) throw new NotFoundException('教师角色分配不存在');
     await this.classTeacherRepo.delete({ id: assignmentId, classId });
     await this.syncClassTeacherIds(classId);
     return { success: true };