A small CLI wrapper + Go test wrapper for @serverless/event-mocks

example.go

func TestHandler(t *testing.T) {
    	req := api.Req{}
	reqBody, _ := json.Marshal(map[string]interface{}{
		"requestContext": map[string]interface{}{
			"Authorizer": map[string]interface{}{
				"claims": map[string]interface{}{
					"cognito:username": "my user",
				},
			},
		},
	})
	assert.MockEvent(t, "apiGateway", string(reqBody), &req)
	claims := req.RequestContext.Authorizer["claims"].(map[string]interface{})
	assert.Equals(t, claims["cognito:username"], "my user")
	res, err := Handler(request)
	// assert the response from your lambda
}

genevent

#!/usr/bin/env node
const createEvent = require("@serverless/event-mocks").default;

const type = process.argv[2];

process.stdin.resume();
process.stdin.setEncoding("utf8");
process.stdin.on("data", function(data) {
  try {
    data = JSON.parse(data);
    process.stdout.write(JSON.stringify(createEvent(`aws:${type}`, data)));
    process.exit(0);
  } catch (e) {
    console.log("Invalid input: " + e.message);
    process.exit(1);
  }
});
setTimeout(() => {
  process.stdin.emit("data", "{}");
}, 50);

/* vim :set ft=js */

mock-events.go

package assert

import (
	"bytes"
	"encoding/json"
	"os/exec"
	"path/filepath"
	"runtime"
	"testing"
)

// MockEvent creates a mock event of one of the following types:
// alexaSkill, alexaSmartphone, apiGateway, cloudWatch, cloudWatchLog,
// cognitoUserPool, dynamo, iot, kinesis, s3, scheduled, ses, sns, websocket
func MockEvent(t *testing.T, eventType string, body string, event interface{}) error {
	t.Helper()
	echo := exec.Command("echo", body)
	gen := exec.Command(getGenPath(), eventType)
	gen.Stdin, _ = echo.StdoutPipe()
	var outBuffer bytes.Buffer
	gen.Stdout = &outBuffer
	_ = gen.Start()
	_ = echo.Run()
	_ = gen.Wait()
	return json.Unmarshal(outBuffer.Bytes(), &event)
}

func getGenPath() string {
	_, filename, _, _ := runtime.Caller(1)
	genPath, _ := filepath.Abs(filepath.Join(filepath.Dir(filename), "../../genevent"))
	return genPath
}

Example command-line usage:

echo "{\"pathParameters\":{\"proxy\": \"world\"}}" | ./genevent apiGateway

output:

{
  "body": "",
  "path": "/test/hello",
  "headers": {
    "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8",
    "Accept-Encoding": "gzip, deflate, lzma, sdch, br",
    "Accept-Language": "en-US,en;q=0.8",
    "CloudFront-Forwarded-Proto": "https",
    "CloudFront-Is-Desktop-Viewer": "true",
    "CloudFront-Is-Mobile-Viewer": "false",
    "CloudFront-Is-SmartTV-Viewer": "false",
    "CloudFront-Is-Tablet-Viewer": "false",
    "CloudFront-Viewer-Country": "US",
    "Host": "wt6mne2s9k.execute-api.us-west-2.amazonaws.com",
    "Upgrade-Insecure-Requests": "1",
    "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36 OPR/39.0.2256.48",
    "Via": "1.1 fb7cca60f0ecd82ce07790c9c5eef16c.cloudfront.net (CloudFront)",
    "X-Amz-Cf-Id": "nBsWBOrSHMgnaROZJK1wGCZ9PcRcSpq_oSXZNQwQ10OTZL4cimZo3g==",
    "X-Forwarded-For": "192.168.100.1, 192.168.1.1",
    "X-Forwarded-Port": "443",
    "X-Forwarded-Proto": "https"
  },
  "pathParameters": {
    "proxy": "world"
  },
  "multiValueHeaders": {},
  "isBase64Encoded": false,
  "multiValueQueryStringParameters": {},
  "requestContext": {
    "accountId": "123456789012",
    "resourceId": "us4z18",
    "stage": "test",
    "requestId": "41b45ea3-70b5-11e6-b7bd-69b5aaebc7d9",
    "identity": {
      "accessKey": "",
      "apiKeyId": "",
      "cognitoIdentityPoolId": "",
      "accountId": "",
      "cognitoIdentityId": "",
      "caller": "",
      "apiKey": "",
      "sourceIp": "192.168.100.1",
      "cognitoAuthenticationType": "",
      "cognitoAuthenticationProvider": "",
      "userArn": "",
      "userAgent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/52.0.2743.82 Safari/537.36 OPR/39.0.2256.48",
      "user": ""
    },
    "path": "",
    "requestTimeEpoch": 0,
    "resourcePath": "/{proxy+}",
    "httpMethod": "GET",
    "apiId": "wt6mne2s9k"
  },
  "resource": "/{proxy+}",
  "httpMethod": "GET",
  "queryStringParameters": {
    "name": "me"
  },
  "stageVariables": {
    "stageVarName": "stageVarValue"
  }
}