aws-lambda-test-utils

Testing your AWS Lambda Functions does not need to be difficult or complex.



If you are new to Amazon WebServices Lambda
(or need a refresher),
please checkout our our
Beginners Guide to AWS Lambda:
https://github.com/dwyl/learn-aws-lambda

## Why?

Testing your code is essential everywhere you need reliability.

AWS Lambda has a Testing _Console_ which is a web-based
way of invoking your function(s) with a given input and
monitoring the result. But this quite slow and cannot be automated (yet).

What?

The simplest possilbe way we could think of for Testing
our AWS Lambda functions.

How? (Usage)

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``sh
npm install aws-lambda-test-utils --save-dev
`

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An example of using the mockContextCreator in an example test.

`js
'use strict';
var test = require('tape');
var utils = require('aws-lambda-test-utils')
var mockContextCreator = utils.mockContextCreator;
var index = require('./index.js'); // lambda function

var ctxOpts = {
functionName: 'LambdaTest',
functionVersion: '1',
invokedFunctionArn: 'arn:aws:lambda:eu-west-1:655240711487:function:LambdaTest:ci'
};
var testEvent = { key1: 'value1' };

test('LambdaTest', function(t){
t.test("LambdaTest: returns value when given event with key1 property", function(st) {
function test(result){
st.equals(result, "value1")
st.end();
};
var context = mockContextCreator({}, test); // no options and test as the callback
index.handler(testEvent, context);
});
t.test("LambdaTest: returns value when given event with key1 property", function(st) {
function test(result){
st.equals(result, "value1")
st.end();
};
var context = mockContextCreator(ctxOpts, test); // context options specified and test as the callback
index.handler(testEvent, context);
});
t.end();
});
`

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`js
var utils = require('aws-lambda-test-utils');

// has 3 methods on it: createDynamoDBEvent, createSNSEvent, createS3Event
var mockEventCreator = utils.mockEventCreator;
`

#### createDynamoDBEvent(options)

Creates a mock DynamoDB event.
`js
var utils = require('aws-lambda-test-utils');
var dynamoEvent = utils.mockEventCreator.createDynamoDBEvent();

// Default options (which can be overridden):
{
awsRegion: "eu-west-1",
eventSourceARN: "arn:aws:dynamodb:us-west-2:account-id:table/ExampleTableWithStream/stream/2015-06-27T00:48:05.899",
events: [{type: "INSERT", number: 1}]
};

`

#### createSNSEvent(options)

`js
var utils = require('aws-lambda-test-utils');
var dynamoEvent = utils.mockEventCreator.createSNSEvent();

// Default options (which can be overridden):
{
message: "default test message"
};

`

#### createS3Event()

`js
var utils = require('aws-lambda-test-utils');
var dynamoEvent = utils.mockEventCreator.createS3Event();

`
#### createAPIGatewayEvent(options)

`js
var utils = require('aws-lambda-test-utils');
var APIGatewayEvent = utils.mockEventCreator.createAPIGatewayEvent();

// Default options (which can be overridden):
{
path: "default/path",
method: "GET",
headers: {
"default-header": 'default'
},
queryStringParameters: {
query: "default"
},
pathParameters: {
uuid: '1234'
},
stageVariables: {
ENV: "test"
},
body: "default body"
}

`

Documentation

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Every AWS Lambda function take two parameters event & context

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The 'context' object has the following form:

`js
{
//methods
success,
done,
fail,
getRemainingTimeInMillis,

//properties
functionName,
functionVersion,
invokedFunctionArn,
memoryLimitInMB,
awsRequestId,
logGroupName,
logStreamName,
identity: {
cognito_identity_id,
cognito_identity_pool_id
},
clientContext: {
client: {
installation_id,
app_title,
app_version_name,
app_version_code,
app_package_name,
Custom,
},
env: {
platform_version
platform,
make,
model,
locale,
}
}
}
`

The properties of the context object can be specified in an options parameter to the mockContextCreator` function.

Background Reading

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TODO

* Add stubs for AWS SDK methods