GroupsService: Create new GroupsService

This service is necessary as we plan to have functions to create and manipulate groups in the future.
The GroupInfoDto was moved from the file note-permissions.dto.ts to mimic the UserInfoDto.

Signed-off-by: Philip Molares <philip.molares@udo.edu>

src/groups/groups.service.spec.ts

@@ -0,0 +1,75 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Test, TestingModule } from '@nestjs/testing';
+import { GroupsService } from './groups.service';
+import { getRepositoryToken } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import { Group } from './group.entity';
+import { NotInDBError } from '../errors/errors';
+import { LoggerModule } from '../logger/logger.module';
+
+describe('GroupsService', () => {
+  let service: GroupsService;
+  let groupRepo: Repository<Group>;
+  let group: Group;
+
+  beforeAll(async () => {
+    const module: TestingModule = await Test.createTestingModule({
+      providers: [
+        GroupsService,
+        {
+          provide: getRepositoryToken(Group),
+          useClass: Repository,
+        },
+      ],
+      imports: [LoggerModule],
+    }).compile();
+
+    service = module.get<GroupsService>(GroupsService);
+    groupRepo = module.get<Repository<Group>>(getRepositoryToken(Group));
+    group = Group.create('testGroup', 'Superheros') as Group;
+  });
+
+  it('should be defined', () => {
+    expect(service).toBeDefined();
+  });
+
+  describe('getGroupByName', () => {
+    it('works', async () => {
+      jest.spyOn(groupRepo, 'findOne').mockResolvedValueOnce(group);
+      const foundGroup = await service.getGroupByName(group.name);
+      expect(foundGroup.name).toEqual(group.name);
+      expect(foundGroup.displayName).toEqual(group.displayName);
+      expect(foundGroup.special).toEqual(group.special);
+    });
+    it('fails with non-existing group', async () => {
+      jest.spyOn(groupRepo, 'findOne').mockResolvedValueOnce(undefined);
+      try {
+        await service.getGroupByName('i_dont_exist');
+      } catch (e) {
+        expect(e).toBeInstanceOf(NotInDBError);
+      }
+    });
+  });
+
+  describe('toGroupDto', () => {
+    it('works', () => {
+      const groupDto = service.toGroupDto(group);
+      expect(groupDto.displayName).toEqual(group.displayName);
+      expect(groupDto.name).toEqual(group.name);
+      expect(groupDto.special).toBeFalsy();
+    });
+    it('fails with null parameter', () => {
+      const groupDto = service.toGroupDto(null);
+      expect(groupDto).toBeNull();
+    });
+    it('fails with undefined parameter', () => {
+      const groupDto = service.toGroupDto(undefined);
+      expect(groupDto).toBeNull();
+    });
+  });
+});