Lambda Test Tool: LambdaAnnotations | Proper use of HttpResults and [FromBody] attribute.

[ashishdhingra]

Discussed in https://github.com/aws/aws-lambda-dotnet/discussions/1569

^{Originally posted by **sergio-asenjo** August 20, 2023} Hello! I've been trying to figure out how to properly use HttpResults returning statement in the "Mock Lambda Test Tool". As a short example, I've tried this: ```C# [LambdaFunction()] [HttpApi(LambdaHttpMethod.Get, "/")] public IHttpResult Test(ILambdaContext context) { return HttpResults.Ok("Ok"); } ``` Doing so, and returning any type of HttpResults, from the UI of Mock Lambda Test Tool I'm getting a base64 return in response. As for this case, I'm getting: `"eyJzdGF0dXNDb2RlIjoyMDAsImhlYWRlcnMiOnsiY29udGVudC10eXBlIjoidGV4dC9wbGFpbiJ9LCJDb29raWVzIjpudWxsLCJib2R5IjoiT2siLCJpc0Jhc2U2NEVuY29kZWQiOmZhbHNlfQ=="` Which translate to: ```json { "statusCode": 200, "headers": { "content-type": "text/plain" }, "Cookies": null, "body": "Ok", "isBase64Encoded": false } ``` That's correct overall, but for testing purposes, having to decode the base64 to see what I got it's not what I would want to do recurrently. Is this intended or am I missing something? If I deploy it, through browsers I can get instantly a decoded response. ─── A second thing is that I'm trying to use a [FromBody] attribute to get some data passed in the body, like this: ```C# [LambdaFunction()] [HttpApi(LambdaHttpMethod.Post, "/")] public IHttpResult Test([FromBody] Request request, ILambdaContext context) { return HttpResults.Ok("Ok"); } public class Request { public string Name { get; set; } } ``` If through the UI Mock Lambda Test Tool I try to send `{ "name": "test" }`, I get a ValidationException, so it doesn't even enter the Test Function completely. This is the response (which is also base64 encoded in the UI). ```C# { "statusCode": 400, "headers": { "Content-Type": "application/json", "x-amzn-ErrorType": "ValidationException" }, "cookies": null, "body": "{\u0022message\u0022: \u00221 validation error(s) detected: Value at \u0027body\u0027 failed to satisfy constraint: Value cannot be null. (Parameter \u0027json\u0027)\u0022}", "isBase64Encoded": false } ``` Am I using this correctly for this case? Before trying annotations, I was using the template that comes with Powertools, there I'd just pass the type (in this case would be Request) and I wouldn't get this error. For both cases, I'm using the base template Serverless Annotation, and deleted what's inside the main Class, everything else is untouched.

[ashishdhingra]

As mentioned by @normj in https://github.com/aws/aws-lambda-dotnet/discussions/1569#discussioncomment-6881199, this is a test tool bug.