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Rudi Starcevic
Rudi Starcevic

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Serverless Framework API End-to-End Testing using Jest and Typescript

#Serverless #Typescript #integrationtesting

Overview

Test your AWS Typescript Serverless API's using Jest

Sample code is here

If you find any typo's or cut-n-paste errors or mistakes please let me know.

Please also comment if you have any improvement suggestions.

The follow steps and examples were created on April 15th 2020 using:

  • Node v12.16.1
  • and Serverless Framework versions: 
Framework Core: 1.67.3 Plugin: 3.6.6 SDK: 2.3.0 Components: 2.29.1

Setup from scratch

The following steps are all command line on a Unix platorm, please adjust for your platorm where required.

Create a new directory and chnage to it (for example):

mkdir serverless-e2e-typescript-example

cd serverless-e2e-typescript-example

Create an AWS Lambda serverless API:

npx serverless create --template aws-nodejs-typescript --name api

Here's an example of the output:

❯ npx serverless create --template aws-nodejs-typescript --name api Serverless: Generating boilerplate... _______ __ | _ .-----.----.--.--.-----.----| .-----.-----.-----. | |___| -__| _| | | -__| _| | -__|__ --|__ --| |____ |_____|__| \___/|_____|__| |__|_____|_____|_____| | | | The Serverless Application Framework | | serverless.com, v1.67.3 -------' Serverless: Successfully generated boilerplate for template: "aws-nodejs-typescript"

Install the node dependencies

npm install

Edit the serverless.yml file so that we can set a default stage and region.

Under the provider section add:

stage: ${opt:stage, 'dev'} region: ${opt:region, 'us-east-1'}

Lets make our API endpoint output only a message and not echo the Lambda input

Edit handler.ts, comment out line 9

// input: event

Deploy the API to the 'dev' stage.

Example deployment command and output:

> npx serverless --stage dev deploy Serverless: Bundling with Webpack... Time: 394ms Built at: 04/15/2020 1:38:22 PM Asset Size Chunks Chunk Names handler.js 1.28 KiB 0 [emitted] handler handler.js.map 5.27 KiB 0 [emitted] [dev] handler Entrypoint handler = handler.js handler.js.map [0] ./handler.ts 316 bytes {0} [built] [1] external "source-map-support/register" 42 bytes {0} [built] Serverless: Package lock found - Using locked versions Serverless: Packing external modules: source-map-support@^0.5.10 Serverless: Packaging service... Serverless: Creating Stack... Serverless: Checking Stack create progress... ........ Serverless: Stack create finished... Serverless: Uploading CloudFormation file to S3... Serverless: Uploading artifacts... Serverless: Uploading service api.zip file to S3 (289.14 KB)... Serverless: Validating template... Serverless: Updating Stack... Serverless: Checking Stack update progress... .............................. Serverless: Stack update finished... Service Information service: api stage: dev region: us-east-1 stack: api-dev resources: 11 api keys: None endpoints: GET - https://driyuairb6.execute-api.us-east-1.amazonaws.com/dev/hello functions: hello: api-dev-hello layers: None Serverless: Run the "serverless" command to setup monitoring, troubleshooting and testing.

Lets call the new API endpoint, copy the hello endpoint from your deployment:

❯ curl https://driyuairb6.execute-api.us-east-1.amazonaws.com/dev/hello { "message": "Go Serverless Webpack (Typescript) v1.0! Your function executed successfully!" } ``

Great! Our new typescript API endpoint is working, lets setup the end-to-end testing.

Install test dependencies:

npm i -D jest ts-jest @types/jest axios

Create a testing directory and Jest config file

mkdir e2e touch e2e/jest.config.js

This is how your jest.config.js file should be:

module.exports = { testEnvironment: "node", transform: { "^.+\\.tsx?$": "ts-jest", }, }

You can create any testing file structure you prefer but for this example we'll be creating files of the test functions then importing them into a single test file describing all the tests in order and assigning them with the imported functions.

Create a test file for the hello API endpoint, I prefer to prefix with a number as it's common to test API endpoints in sequence:

Create the file 100_hello.ts with the code content:

import axios from "axios" const url = process.env.URL export const helloTest = () => { test("should reply success", async () => { const res = await axios.get(`${url}/hello`) expect(res.status).toEqual(200) expect(res.data.message).toMatch(/Your function executed successfully!/) }) }

Create the test suite runner file index.test.js with the code content:

import { helloTest } from "./100_hello" describe("hello", helloTest)

Lets run the end-to-end test manually first, then we'll create an npm script to simplify it:

 URL=https://driyuairb6.execute-api.us-east-1.amazonaws.com/dev ./node_modules/.bin/jest -c e2e/jest.config.js --runInBand --bail ts-jest[config] (WARN) message TS151001: If you have issues related to imports, you should consider setting `esModuleInterop` to `true` in your TypeScript configuration file (usually `tsconfig.json`). See https://blogs.msdn.microsoft.com/typescript/2018/01/31/announcing-typescript-2-7/#easier-ecmascript-module-interoperability for more information. PASS e2e/index.test.ts hello ✓ should reply success (474ms) Test Suites: 1 passed, 1 total Tests: 1 passed, 1 total Snapshots: 0 total Time: 1.059s, estimated 2s Ran all test suites.

Yay! Our end-to-end test passes.

Let's fix that ts-jest warning by adding "esModuleInterop": true in the tsconfig.json file

"esModuleInterop": true

Run the tests manually again:

URL=https://driyuairb6.execute-api.us-east-1.amazonaws.com/dev ./node_modules/.bin/jest -c e2e/jest.config.js --runInBand --bail PASS e2e/index.test.ts hello ✓ should reply success (489ms) Test Suites: 1 passed, 1 total Tests: 1 passed, 1 total Snapshots: 0 total Time: 0.96s, estimated 2s Ran all test suites.

Next lets create an npm script in package.json:

"scripts": { "test": "echo \"Error: no test specified\" && exit 1", "e2e": "jest -c e2e/jest.config.js --runInBand --bail e2e" },

Now we can run our tests with:

URL=https://driyuairb6.execute-api.us-east-1.amazonaws.com/dev npm run e2e > api@1.0.0 e2e /home/rudi/projects/serverless-e2e-typescript-example > jest -c e2e/jest.config.js --runInBand e2e PASS e2e/index.test.ts hello ✓ should reply success (474ms) Test Suites: 1 passed, 1 total Tests: 1 passed, 1 total Snapshots: 0 total Time: 1.001s Ran all test suites matching /e2e/i.

Finally lets clean up with:

npx serverless --stage dev remove

npx serverless --stage dev remove Serverless: Getting all objects in S3 bucket... Serverless: Removing objects in S3 bucket... Serverless: Removing Stack... Serverless: Checking Stack removal progress... ............. Serverless: Stack removal finished...

Credits

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