refactor: optimize DbLoadAnswersBySurvey

src/data/protocols/db/survey/index.ts

@@ -1,4 +1,5 @@
 export * from './add-survey-repository'
 export * from './load-survey-by-id-repository'
+export * from './load-answers-by-survey-repository'
 export * from './check-survey-by-id-repository'
 export * from './load-surveys-repository'

src/data/protocols/db/survey/load-answers-by-survey-repository.ts

@@ -0,0 +1,7 @@
+export interface LoadAnswersBySurveyRepository {
+  loadAnswers: (id: string) => Promise<LoadAnswersBySurveyRepository.Result>
+}
+
+export namespace LoadAnswersBySurveyRepository {
+  export type Result = string[]
+}

src/data/usecases/db-load-answers-by-survey.ts

@@ -1,11 +1,10 @@
 import { LoadAnswersBySurvey } from '@/domain/usecases'
-import { LoadSurveyByIdRepository } from '@/data/protocols'
+import { LoadAnswersBySurveyRepository } from '@/data/protocols'
 
 export class DbLoadAnswersBySurvey implements LoadAnswersBySurvey {
-  constructor (private readonly loadSurveyByIdRepository: LoadSurveyByIdRepository) {}
+  constructor (private readonly loadAnswersBySurveyRepository: LoadAnswersBySurveyRepository) {}
 
   async loadAnswers (id: string): Promise<LoadAnswersBySurvey.Result> {
-    const survey = await this.loadSurveyByIdRepository.loadById(id)
-    return survey?.answers.map(a => a.answer) || []
+    return this.loadAnswersBySurveyRepository.loadAnswers(id)
   }
 }

src/infra/db/mongodb/survey-mongo-repository.ts

@@ -1,10 +1,10 @@
 import { MongoHelper, QueryBuilder } from '@/infra/db'
 import { SurveyModel } from '@/domain/models'
-import { AddSurveyRepository, LoadSurveysRepository, LoadSurveyByIdRepository, CheckSurveyByIdRepository } from '@/data/protocols/db'
+import { AddSurveyRepository, LoadSurveysRepository, LoadSurveyByIdRepository, CheckSurveyByIdRepository, LoadAnswersBySurveyRepository } from '@/data/protocols/db'
 
 import { ObjectId } from 'mongodb'
 
-export class SurveyMongoRepository implements AddSurveyRepository, LoadSurveysRepository, LoadSurveyByIdRepository, CheckSurveyByIdRepository {
+export class SurveyMongoRepository implements AddSurveyRepository, LoadSurveysRepository, LoadSurveyByIdRepository, CheckSurveyByIdRepository, LoadAnswersBySurveyRepository {
   async add (data: AddSurveyRepository.Params): Promise<void> {
     const surveyCollection = await MongoHelper.getCollection('surveys')
     await surveyCollection.insertOne(data)
@@ -49,6 +49,21 @@ export class SurveyMongoRepository implements AddSurveyRepository, LoadSurveysRe
     return survey && MongoHelper.map(survey)
   }
 
+  async loadAnswers (id: string): Promise<LoadAnswersBySurveyRepository.Result> {
+    const surveyCollection = await MongoHelper.getCollection('surveys')
+    const query = new QueryBuilder()
+      .match({
+        _id: new ObjectId(id)
+      })
+      .project({
+        _id: 0,
+        answers: '$answers.answer'
+      })
+      .build()
+    const surveys = await surveyCollection.aggregate(query).toArray()
+    return surveys[0]?.answers || []
+  }
+
   async checkById (id: string): Promise<CheckSurveyByIdRepository.Result> {
     const surveyCollection = await MongoHelper.getCollection('surveys')
     const survey = await surveyCollection.findOne({

tests/data/mocks/mock-db-survey.ts

@@ -1,7 +1,9 @@
-import { AddSurveyRepository, LoadSurveyByIdRepository, LoadSurveysRepository, CheckSurveyByIdRepository } from '@/data/protocols'
+import { AddSurveyRepository, LoadSurveyByIdRepository, LoadSurveysRepository, CheckSurveyByIdRepository, LoadAnswersBySurveyRepository } from '@/data/protocols'
 import { SurveyModel } from '@/domain/models'
 import { mockSurveyModel, mockSurveyModels } from '@/tests/domain/mocks'
 
+import faker from 'faker'
+
 export class AddSurveyRepositorySpy implements AddSurveyRepository {
   addSurveyParams: AddSurveyRepository.Params
 
@@ -20,6 +22,16 @@ export class LoadSurveyByIdRepositorySpy implements LoadSurveyByIdRepository {
   }
 }
 
+export class LoadAnswersBySurveyRepositorySpy implements LoadAnswersBySurveyRepository {
+  result = [faker.random.word(), faker.random.word()]
+  id: string
+
+  async loadAnswers (id: string): Promise<LoadAnswersBySurveyRepository.Result> {
+    this.id = id
+    return this.result
+  }
+}
+
 export class CheckSurveyByIdRepositorySpy implements CheckSurveyByIdRepository {
   result = true
   id: string

tests/data/usecases/db-load-answers-by-survey.spec.ts

@@ -1,20 +1,20 @@
 import { DbLoadAnswersBySurvey } from '@/data/usecases'
-import { LoadSurveyByIdRepositorySpy } from '@/tests/data/mocks'
+import { LoadAnswersBySurveyRepositorySpy } from '@/tests/data/mocks'
 import { throwError } from '@/tests/domain/mocks'
 
 import faker from 'faker'
 
 type SutTypes = {
   sut: DbLoadAnswersBySurvey
-  loadSurveyByIdRepositorySpy: LoadSurveyByIdRepositorySpy
+  loadAnswersBySurveyRepositorySpy: LoadAnswersBySurveyRepositorySpy
 }
 
 const makeSut = (): SutTypes => {
-  const loadSurveyByIdRepositorySpy = new LoadSurveyByIdRepositorySpy()
-  const sut = new DbLoadAnswersBySurvey(loadSurveyByIdRepositorySpy)
+  const loadAnswersBySurveyRepositorySpy = new LoadAnswersBySurveyRepositorySpy()
+  const sut = new DbLoadAnswersBySurvey(loadAnswersBySurveyRepositorySpy)
   return {
     sut,
-    loadSurveyByIdRepositorySpy
+    loadAnswersBySurveyRepositorySpy
   }
 }
 
@@ -25,31 +25,31 @@ describe('DbLoadAnswersBySurvey', () => {
     surveyId = faker.random.uuid()
   })
 
-  test('Should call LoadSurveyByIdRepository', async () => {
-    const { sut, loadSurveyByIdRepositorySpy } = makeSut()
+  test('Should call LoadAnswersBySurveyRepository', async () => {
+    const { sut, loadAnswersBySurveyRepositorySpy } = makeSut()
     await sut.loadAnswers(surveyId)
-    expect(loadSurveyByIdRepositorySpy.id).toBe(surveyId)
+    expect(loadAnswersBySurveyRepositorySpy.id).toBe(surveyId)
   })
 
   test('Should return answers on success', async () => {
-    const { sut, loadSurveyByIdRepositorySpy } = makeSut()
+    const { sut, loadAnswersBySurveyRepositorySpy } = makeSut()
     const answers = await sut.loadAnswers(surveyId)
     expect(answers).toEqual([
-      loadSurveyByIdRepositorySpy.result.answers[0].answer,
-      loadSurveyByIdRepositorySpy.result.answers[1].answer
+      loadAnswersBySurveyRepositorySpy.result[0],
+      loadAnswersBySurveyRepositorySpy.result[1]
     ])
   })
 
-  test('Should return empty array if LoadSurveyByIdRepository returns null', async () => {
-    const { sut, loadSurveyByIdRepositorySpy } = makeSut()
-    loadSurveyByIdRepositorySpy.result = null
+  test('Should return empty array if LoadAnswersBySurveyRepository returns []', async () => {
+    const { sut, loadAnswersBySurveyRepositorySpy } = makeSut()
+    loadAnswersBySurveyRepositorySpy.result = []
     const answers = await sut.loadAnswers(surveyId)
     expect(answers).toEqual([])
   })
 
-  test('Should throw if LoadSurveyByIdRepository throws', async () => {
-    const { sut, loadSurveyByIdRepositorySpy } = makeSut()
-    jest.spyOn(loadSurveyByIdRepositorySpy, 'loadById').mockImplementationOnce(throwError)
+  test('Should throw if LoadAnswersBySurveyRepository throws', async () => {
+    const { sut, loadAnswersBySurveyRepositorySpy } = makeSut()
+    jest.spyOn(loadAnswersBySurveyRepositorySpy, 'loadAnswers').mockImplementationOnce(throwError)
     const promise = sut.loadAnswers(surveyId)
     await expect(promise).rejects.toThrow()
   })

tests/infra/db/mongodb/survey-mongo-repository.spec.ts

@@ -82,6 +82,28 @@ describe('SurveyMongoRepository', () => {
       expect(survey).toBeTruthy()
       expect(survey.id).toBeTruthy()
     })
+
+    test('Should return null if survey does not exists', async () => {
+      const sut = makeSut()
+      const survey = await sut.loadById(FakeObjectId.generate())
+      expect(survey).toBeFalsy()
+    })
+  })
+
+  describe('loadAnswers()', () => {
+    test('Should load answers on success', async () => {
+      const res = await surveyCollection.insertOne(mockAddSurveyParams())
+      const survey = res.ops[0]
+      const sut = makeSut()
+      const answers = await sut.loadAnswers(survey._id)
+      expect(answers).toEqual([survey.answers[0].answer, survey.answers[1].answer])
+    })
+
+    test('Should return empty array if survey does not exists', async () => {
+      const sut = makeSut()
+      const answers = await sut.loadAnswers(FakeObjectId.generate())
+      expect(answers).toEqual([])
+    })
   })
 
   describe('checkById()', () => {