feat(api): write register course user implement slice (#328) (#366)

* command

* command handler

* register course user function

* module

* env.example semicolon removal

Author: kacper-cyra

packages/api/.env.example

@@ -12,5 +12,5 @@ COOKIE_SECRET="89YHGASP9DYFHWEOIH098yasd8rtwepuddrw902"
 
 PROCESS_ST_CHECKLIST_URL="https://app.process.st/workflows/CodersCamp-Test-Checklist-kTrxJoZgP-9IabhRbohIrw/run-link"
 EVENT_REPOSITORY="prisma"
-SUBSCRIPTION_QUEUE_MAX_RETRY_COUNT=10;
-SUBSCRIPTION_QUEUE_WAITING_TIME_ON_RETRY_MS=100;
+SUBSCRIPTION_QUEUE_MAX_RETRY_COUNT=10
+SUBSCRIPTION_QUEUE_WAITING_TIME_ON_RETRY_MS=100

packages/api/src/app.module.ts

@@ -13,6 +13,7 @@ import { env } from '@/shared/env';
 import { EmailConfirmationWriteModule } from '@/write/email-confirmation/email-confirmation.write-module';
 import { LearningMaterialsTasksModule } from '@/write/learning-materials-tasks/learning-materials-tasks.write-module';
 import { LearningMaterialsUrlWriteModule } from '@/write/learning-materials-url/learning-materials-url.write-module';
+import { RegisterCourseUserWriteModule } from '@/write/register-course-user/register-course-user.write-module';
 import { UserRegistrationWriteModule } from '@/write/user-registration/user-registration.write-module';
 
 import { AuthModule } from './crud/auth/auth.module';
@@ -26,6 +27,7 @@ const writeModules = [
   UserRegistrationWriteModule,
   LearningMaterialsTasksModule,
   EmailConfirmationWriteModule,
+  RegisterCourseUserWriteModule,
 ];
 const readModules = [LearningMaterialsReadModule, CourseProgressReadModule];
 const automationModules = [

packages/api/src/module/shared/commands/register-course-user.ts

@@ -0,0 +1,12 @@
+import { AbstractApplicationCommand } from '@/module/application-command-events';
+
+export type RegisterCourseUser = {
+  type: 'RegisterCourseUser';
+  data: {
+    userId: string;
+    courseUserId: string;
+    courseId: string;
+  };
+};
+
+export class RegisterCourseUserApplicationCommand extends AbstractApplicationCommand<RegisterCourseUser> {}

packages/api/src/module/write/register-course-user/application/register-course-user.command-handler.ts

@@ -0,0 +1,29 @@
+import { Inject } from '@nestjs/common';
+import { CommandHandler, ICommandHandler } from '@nestjs/cqrs';
+
+import { RegisterCourseUserApplicationCommand } from '@/module/commands/register-course-user';
+import { CourseUserWasRegistered } from '@/module/events/course-user-was-registered.domain-event';
+import { APPLICATION_SERVICE, ApplicationService } from '@/write/shared/application/application-service';
+import { EventStreamName } from '@/write/shared/application/event-stream-name.value-object';
+
+import { registerCourseUser } from '../domain/register-course-user';
+
+@CommandHandler(RegisterCourseUserApplicationCommand)
+export class RegisterCourseUserApplicationCommandHandler
+  implements ICommandHandler<RegisterCourseUserApplicationCommand>
+{
+  constructor(
+    @Inject(APPLICATION_SERVICE)
+    private readonly applicationService: ApplicationService,
+  ) {}
+
+  async execute(command: RegisterCourseUserApplicationCommand): Promise<void> {
+    const eventStreamName = EventStreamName.from('CourseUser', `${command.data.courseId}_${command.data.userId}`);
+
+    await this.applicationService.execute<CourseUserWasRegistered>(
+      eventStreamName,
+      { causationId: command.id, correlationId: command.metadata.correlationId },
+      (pastEvents) => registerCourseUser(pastEvents, command),
+    );
+  }
+}

packages/api/src/module/write/register-course-user/domain/register-course-user.spec.ts

@@ -0,0 +1,37 @@
+import { RegisterCourseUser } from '@/module/commands/register-course-user';
+import { CourseUserWasRegistered } from '@/module/events/course-user-was-registered.domain-event';
+
+import { registerCourseUser } from './register-course-user';
+
+describe('register course user', () => {
+  const command: RegisterCourseUser = {
+    type: 'RegisterCourseUser',
+    data: {
+      userId: 'vvcwfOgoTHVrVLf4Ky5e6',
+      courseUserId: 'F7IXr5vnCVWfe1oD9u7tz',
+      courseId: 'iyt46Z6Mjifxmb_cZqwmb',
+    },
+  };
+
+  it('should return CourseUserWasRegistered if user is not registered', () => {
+    // Given
+    const pastEvents: CourseUserWasRegistered[] = [];
+
+    // When
+    const events = registerCourseUser(pastEvents, command);
+
+    // Then
+    expect(events).toStrictEqual([{ type: 'CourseUserWasRegistered', data: command.data }]);
+  });
+
+  it('should throw error if user have been already registered', () => {
+    // Given
+    const pastEvents: CourseUserWasRegistered[] = [{ type: 'CourseUserWasRegistered', data: command.data }];
+
+    // When
+    const events = () => registerCourseUser(pastEvents, command);
+
+    // Then
+    expect(events).toThrow();
+  });
+});

packages/api/src/module/write/register-course-user/domain/register-course-user.ts

@@ -0,0 +1,32 @@
+import { RegisterCourseUser } from '@/module/commands/register-course-user';
+import { CourseUserWasRegistered } from '@/module/events/course-user-was-registered.domain-event';
+
+export function registerCourseUser(
+  pastEvents: CourseUserWasRegistered[],
+  { data }: RegisterCourseUser,
+): CourseUserWasRegistered[] {
+  const state = pastEvents.reduce<{ registered: boolean }>(
+    (acc, event) => {
+      switch (event.type) {
+        case 'CourseUserWasRegistered': {
+          return { registered: true };
+        }
+        default: {
+          return acc;
+        }
+      }
+    },
+    { registered: false },
+  );
+
+  if (state.registered) {
+    throw new Error('Course user already registered');
+  }
+
+  const newEvent: CourseUserWasRegistered = {
+    type: 'CourseUserWasRegistered',
+    data,
+  };
+
+  return [newEvent];
+}

packages/api/src/module/write/register-course-user/register-course-user.test-module.ts

@@ -0,0 +1,5 @@
+import { initWriteTestModule } from '@/shared/test-utils';
+
+export async function registerCourseUserTestModule() {
+  return initWriteTestModule();
+}

packages/api/src/module/write/register-course-user/register-course-user.write-module.spec.ts

@@ -0,0 +1,46 @@
+import { AsyncReturnType } from 'type-fest';
+
+import { RegisterCourseUserApplicationCommand } from '@/module/commands/register-course-user';
+import { CourseUserWasRegistered } from '@/module/events/course-user-was-registered.domain-event';
+
+import { EventStreamName } from '../shared/application/event-stream-name.value-object';
+import { registerCourseUserTestModule } from './register-course-user.test-module';
+
+describe('registerCourseUserModule', () => {
+  let module: AsyncReturnType<typeof registerCourseUserTestModule>;
+  const commandBuilder = (userId = '', courseUserId = '', courseId = '') => ({
+    class: RegisterCourseUserApplicationCommand,
+    type: 'RegisterCourseUser',
+    data: { userId, courseUserId, courseId },
+  });
+
+  it('should register new course user', async () => {
+    // Given
+    const command = commandBuilder();
+
+    // When
+    await module.executeCommand(() => command);
+
+    // Then
+    module.expectEventPublishedLastly<CourseUserWasRegistered>({
+      type: 'CourseUserWasRegistered',
+      data: { userId: command.data.userId, courseUserId: command.data.courseUserId, courseId: command.data.courseId },
+      streamName: EventStreamName.from('CourseUser', `${command.data.courseId}_${command.data.userId}`),
+    });
+  });
+
+  it('should not register new user if one already exists', async () => {
+    // Given
+    const command = commandBuilder();
+
+    // When
+    await module.executeCommand(() => command);
+
+    // Then
+    await expect(() => module.executeCommand(() => command)).rejects.toThrow();
+  });
+
+  beforeEach(async () => {
+    module = await registerCourseUserTestModule();
+  });
+});

packages/api/src/module/write/register-course-user/register-course-user.write-module.ts

@@ -0,0 +1,11 @@
+import { Module } from '@nestjs/common';
+
+import { SharedModule } from '../shared/shared.module';
+import { RegisterCourseUserApplicationCommandHandler } from './application/register-course-user.command-handler';
+
+@Module({
+  imports: [SharedModule],
+  providers: [RegisterCourseUserApplicationCommandHandler],
+  exports: [],
+})
+export class RegisterCourseUserWriteModule {}