Add dependency container

Author: francisco-videira-nhs

lambdas/api-handler/src/config/__tests__/deps.test.ts

@@ -1,7 +1,7 @@
 
 import type { Deps } from '../deps';
 
-describe('getDeps()', () => {
+describe('createDependenciesContainer', () => {
   beforeEach(() => {
     jest.clearAllMocks();
     jest.resetModules();
@@ -28,12 +28,12 @@ describe('getDeps()', () => {
 
     // Env
     jest.mock('../env', () => ({
-      lambdaEnv: {
+      envVars: {
         LETTERS_TABLE_NAME: 'LettersTable',
-        LETTER_TTL_HOURS: '24',
+        LETTER_TTL_HOURS: 24,
         SUPPLIER_ID_HEADER: 'nhsd-supplier-id',
         APIM_CORRELATION_HEADER: 'nhsd-correlation-id',
-        DOWNLOAD_URL_TTL_SECONDS: '3600'
+        DOWNLOAD_URL_TTL_SECONDS: 3600
       },
     }));
   });
@@ -44,8 +44,8 @@ describe('getDeps()', () => {
     const pinoMock = jest.requireMock('pino') as { default: jest.Mock };
     const { LetterRepository } = jest.requireMock('../../../../../internal/datastore') as { LetterRepository: jest.Mock };
 
-    const { getDeps } = require('../deps');
-    const deps: Deps = getDeps();
+    const { createDependenciesContainer } = require('../deps');
+    const deps: Deps = createDependenciesContainer();
 
     expect(S3Client).toHaveBeenCalledTimes(1);
     expect(pinoMock.default).toHaveBeenCalledTimes(1);
@@ -59,27 +59,10 @@ describe('getDeps()', () => {
 
     expect(deps.env).toEqual({
       LETTERS_TABLE_NAME: 'LettersTable',
-      LETTER_TTL_HOURS: '24',
+      LETTER_TTL_HOURS: 24,
       SUPPLIER_ID_HEADER: 'nhsd-supplier-id',
       APIM_CORRELATION_HEADER: 'nhsd-correlation-id',
-      DOWNLOAD_URL_TTL_SECONDS: '3600'
+      DOWNLOAD_URL_TTL_SECONDS: 3600
     });
   });
-
-  test('is a singleton (second call returns the same object; constructors not re-run)', async () => {
-    // get current mock instances
-    const { S3Client } = jest.requireMock('@aws-sdk/client-s3') as { S3Client: jest.Mock };
-    const pinoMock = jest.requireMock('pino') as { default: jest.Mock };
-    const { LetterRepository } = jest.requireMock('../../../../../internal/datastore') as { LetterRepository: jest.Mock };
-
-    const { getDeps } = require('../deps');
-
-    const first = getDeps();
-    const second = getDeps();
-
-    expect(first).toBe(second);
-    expect(S3Client).toHaveBeenCalledTimes(1);
-    expect(LetterRepository).toHaveBeenCalledTimes(1);
-    expect(pinoMock.default).toHaveBeenCalledTimes(1);
-  });
 });

lambdas/api-handler/src/config/__tests__/env.test.ts

@@ -1,3 +1,5 @@
+import { ZodError } from 'zod';
+
 describe('lambdaEnv', () => {
   const OLD_ENV = process.env;
 
@@ -17,14 +19,14 @@ describe('lambdaEnv', () => {
     process.env.LETTER_TTL_HOURS = '24';
     process.env.DOWNLOAD_URL_TTL_SECONDS = '3600';
 
-    const { lambdaEnv } = require('../env');
+    const { envVars } = require('../env');
 
-    expect(lambdaEnv).toEqual({
+    expect(envVars).toEqual({
       SUPPLIER_ID_HEADER: 'x-supplier-id',
       APIM_CORRELATION_HEADER: 'x-correlation-id',
       LETTERS_TABLE_NAME: 'letters-table',
-      LETTER_TTL_HOURS: '24',
-      DOWNLOAD_URL_TTL_SECONDS: '3600'
+      LETTER_TTL_HOURS: 24,
+      DOWNLOAD_URL_TTL_SECONDS: 3600
     });
   });
 
@@ -35,8 +37,6 @@ describe('lambdaEnv', () => {
     process.env.LETTER_TTL_HOURS = '24';
     process.env.DOWNLOAD_URL_TTL_SECONDS = '3600';
 
-    expect(() => require('../env')).toThrow(
-      'Missing required env var: LETTERS_TABLE_NAME'
-    );
+    expect(() => require('../env')).toThrow(ZodError);
   });
 });

lambdas/api-handler/src/config/deps.ts

@@ -3,40 +3,34 @@ import { DynamoDBClient } from '@aws-sdk/client-dynamodb';
 import { DynamoDBDocumentClient } from '@aws-sdk/lib-dynamodb';
 import pino from 'pino';
 import { LetterRepository } from '../../../../internal/datastore';
-import { lambdaEnv, LambdaEnv } from "../config/env";
-
-let singletonDeps: Deps | null = null;
+import { envVars, EnvVars } from "../config/env";
 
 export type Deps = {
   s3Client: S3Client;
   letterRepo: LetterRepository;
   logger: pino.Logger,
-  env: LambdaEnv
+  env: EnvVars
 };
 
-function createLetterRepository(log: pino.Logger, lambdaEnv: LambdaEnv): LetterRepository {
+function createLetterRepository(log: pino.Logger, envVars: EnvVars): LetterRepository {
   const ddbClient = new DynamoDBClient({});
   const docClient = DynamoDBDocumentClient.from(ddbClient);
   const config = {
-    lettersTableName: lambdaEnv.LETTERS_TABLE_NAME,
-    ttlHours: Number.parseInt(lambdaEnv.LETTER_TTL_HOURS)
+    lettersTableName: envVars.LETTERS_TABLE_NAME,
+    ttlHours: envVars.LETTER_TTL_HOURS
   };
 
   return new LetterRepository(docClient, log, config);
 }
 
-export function getDeps(): Deps {
-
-  if (singletonDeps) return singletonDeps;
+export function createDependenciesContainer(): Deps {
 
   const log = pino();
 
-  singletonDeps = {
+  return {
     s3Client: new S3Client(),
-    letterRepo: createLetterRepository(log, lambdaEnv),
+    letterRepo: createLetterRepository(log, envVars),
     logger: log,
-    env: lambdaEnv
+    env: envVars
   };
-
-  return singletonDeps;
 }

lambdas/api-handler/src/config/env.ts

@@ -1,23 +1,13 @@
-export interface LambdaEnv {
-  SUPPLIER_ID_HEADER: string;
-  APIM_CORRELATION_HEADER: string;
-  LETTERS_TABLE_NAME: string;
-  LETTER_TTL_HOURS: string;
-  DOWNLOAD_URL_TTL_SECONDS: string;
-}
+import {z} from 'zod';
 
-export const lambdaEnv: LambdaEnv = {
-  SUPPLIER_ID_HEADER: getEnv('SUPPLIER_ID_HEADER'),
-  APIM_CORRELATION_HEADER: getEnv('APIM_CORRELATION_HEADER'),
-  LETTERS_TABLE_NAME: getEnv('LETTERS_TABLE_NAME'),
-  LETTER_TTL_HOURS: getEnv('LETTER_TTL_HOURS'),
-  DOWNLOAD_URL_TTL_SECONDS: getEnv('DOWNLOAD_URL_TTL_SECONDS')
-};
+const EnvVarsSchema = z.object({
+  SUPPLIER_ID_HEADER: z.string(),
+  APIM_CORRELATION_HEADER: z.string(),
+  LETTERS_TABLE_NAME: z.string(),
+  LETTER_TTL_HOURS: z.coerce.number().int(),
+  DOWNLOAD_URL_TTL_SECONDS: z.coerce.number().int()
+});
 
-function getEnv(name: string): string {
-  const value = process.env[name];
-  if (!value) {
-    throw new Error(`Missing required env var: ${name}`);
-  }
-  return value;
-}
+export type EnvVars = z.infer<typeof EnvVarsSchema>;
+
+export const envVars = EnvVarsSchema.parse(process.env);

lambdas/api-handler/src/handlers/__tests__/get-letter-data.test.ts

@@ -12,37 +12,33 @@ mockedMapErrorToResponse.mockReturnValue(expectedErrorResponse);
 jest.mock('../../services/letter-operations');
 import * as letterService from '../../services/letter-operations';
 
-// mock dependencies
-jest.mock("../../config/deps", () => ({ getDeps: jest.fn() }));
-import { Deps, getDeps } from "../../config/deps";
-const mockedGetDeps = getDeps as jest.Mock<Deps>;
-const fakeDeps: jest.Mocked<Deps> = {
-  s3Client: {} as unknown as S3Client,
-  letterRepo: {} as unknown as LetterRepository,
-  logger: { info: jest.fn(), error: jest.fn() } as unknown as pino.Logger,
-  env: {
-    SUPPLIER_ID_HEADER: 'nhsd-supplier-id',
-    APIM_CORRELATION_HEADER: 'nhsd-correlation-id',
-    LETTERS_TABLE_NAME: 'LETTERS_TABLE_NAME',
-    LETTER_TTL_HOURS: 'LETTER_TTL_HOURS',
-    DOWNLOAD_URL_TTL_SECONDS: 'DOWNLOAD_URL_TTL_SECONDS'
-  } as unknown as LambdaEnv
-}
-mockedGetDeps.mockReturnValue(fakeDeps);
-
 import type { APIGatewayProxyResult, Context } from 'aws-lambda';
 import { mockDeep } from 'jest-mock-extended';
 import { makeApiGwEvent } from './utils/test-utils';
 import { ValidationError } from '../../errors';
 import * as errors from '../../contracts/errors';
-import { getLetterData } from '../get-letter-data';
+import { createGetLetterDataHandler } from '../get-letter-data';
 import { S3Client } from '@aws-sdk/client-s3';
 import pino from 'pino';
 import { LetterRepository } from '../../../../../internal/datastore/src';
-import { LambdaEnv } from '../../config/env';
+import { EnvVars } from '../../config/env';
+import { Deps } from "../../config/deps";
 
 describe('API Lambda handler', () => {
 
+  const mockedDeps: jest.Mocked<Deps> = {
+    s3Client: {} as unknown as S3Client,
+    letterRepo: {} as unknown as LetterRepository,
+    logger: { info: jest.fn(), error: jest.fn() } as unknown as pino.Logger,
+    env: {
+      SUPPLIER_ID_HEADER: 'nhsd-supplier-id',
+      APIM_CORRELATION_HEADER: 'nhsd-correlation-id',
+      LETTERS_TABLE_NAME: 'LETTERS_TABLE_NAME',
+      LETTER_TTL_HOURS: 1,
+      DOWNLOAD_URL_TTL_SECONDS: 1
+    } as unknown as EnvVars
+  }
+
   beforeEach(() => {
     jest.clearAllMocks();
   });
@@ -59,7 +55,8 @@ describe('API Lambda handler', () => {
     const context = mockDeep<Context>();
     const callback = jest.fn();
 
-    const result = await getLetterData(event, context, callback);
+    const getLetterDataHandler = createGetLetterDataHandler(mockedDeps);
+    const result = await getLetterDataHandler(event, context, callback);
 
     expect(result).toEqual({
       statusCode: 303,
@@ -77,9 +74,10 @@ describe('API Lambda handler', () => {
     const context = mockDeep<Context>();
     const callback = jest.fn();
 
-    const result = await getLetterData(event, context, callback);
+    const getLetterDataHandler = createGetLetterDataHandler(mockedDeps);
+    const result = await getLetterDataHandler(event, context, callback);
 
-    expect(mockedMapErrorToResponse).toHaveBeenCalledWith(new Error('The request headers are empty'), undefined, mockedGetDeps().logger);
+    expect(mockedMapErrorToResponse).toHaveBeenCalledWith(new Error('The request headers are empty'), undefined, mockedDeps.logger);
     expect(result).toEqual(expectedErrorResponse);
   });
 
@@ -93,9 +91,10 @@ describe('API Lambda handler', () => {
     const context = mockDeep<Context>();
     const callback = jest.fn();
 
-    const result = await getLetterData(event, context, callback);
+    const getLetterDataHandler = createGetLetterDataHandler(mockedDeps);
+    const result = await getLetterDataHandler(event, context, callback);
 
-    expect(mockedMapErrorToResponse).toHaveBeenCalledWith(new Error("The request headers don't contain the APIM correlation id"), undefined, mockedGetDeps().logger);
+    expect(mockedMapErrorToResponse).toHaveBeenCalledWith(new Error("The request headers don't contain the APIM correlation id"), undefined, mockedDeps.logger);
     expect(result).toEqual(expectedErrorResponse);
   });
 
@@ -107,9 +106,10 @@ describe('API Lambda handler', () => {
     const context = mockDeep<Context>();
     const callback = jest.fn();
 
-    const result = await getLetterData(event, context, callback);
+    const getLetterDataHandler = createGetLetterDataHandler(mockedDeps);
+    const result = await getLetterDataHandler(event, context, callback);
 
-    expect(mockedMapErrorToResponse).toHaveBeenCalledWith(new ValidationError(errors.ApiErrorDetail.InvalidRequestMissingLetterIdPathParameter), 'correlationId', mockedGetDeps().logger);
+    expect(mockedMapErrorToResponse).toHaveBeenCalledWith(new ValidationError(errors.ApiErrorDetail.InvalidRequestMissingLetterIdPathParameter), 'correlationId', mockedDeps.logger);
     expect(result).toEqual(expectedErrorResponse);
   });
 });