Mock DocumentClient

[pjarts]

Is it possible to use this package to mock a DocumentClient instance?

[damonmaria]

I use the dynamodb-local script in this package and run a real DocumentClient against that (as per the README) which is a more accurate test of the code. I find it performant enough even for unit tests.

I haven't tried mocking DocumentClient using mockService. I'm not sure if there would be issues with it because it's not a top level server like DynamoDB is. Have you tried and it doesn't work?

[pjarts]

mockService(AWS.DynamoDB.DocumentClient, ['query'])

TypeError {
  message: 'Cannot read property \'undefined\' of undefined',
}

Testing agains a local DynamoDB might be a better choice. It would require a bit of setup with out deployment pipeline though as I assume it requires Java?

I found one workaround is to use the DynamoDB client instead of the DocumentClient and import the marshall and unmarshall methods from 'aws-sdk/lib/dynamodb/converter' to convert JS objects into DynamoDB objects and vice versa.

[damonmaria]

I've done some more investigation on DocumnetClient and underneath it's not treated as an 'service' by AWS. Which makes sense, since it's basically a wrapper around DynamoDB. As such there isn't a service API to load which would validate the requests you make while testing. And therefore you're basically back to just a plain sinon.spy().

So while it would be nice, I don't think there's a way to achieve anything of value. And especially when you can test against a local DynamoDB instance. But yes, this does require Java.