SDK Error types (ResourceNotFoundError etc) should be exposed as constructable values to allow for unit test mocks

[dmeehan1968]

Errors are exposed only as types, which means that its not easy to create mocks for the AWS services. Example for jest/jest-mock-extended:

    this.scheduler = mock<Context.Tag.Service<SchedulerService>>()

    this.scheduler.updateSchedule.mockReturnValue(
      Effect.fail({
        ...new ResourceNotFoundException({
          message: 'not found',
          Message: 'Not Found',
          $metadata: {},
        }),
        _tag: 'ResourceNotFoundException',
      }),
    )

Usability could be vastly improved by providing a constructor for the error, with some possible optimisation to provide sensible defaults, eg.:

this.scheduler.updateSchedule.mockReturnValue(
  Effect.fail(new ResourceNotFoundError({ Message: 'Not Found' }))
)

One could apply a kludge such as:

this.scheduler.updateSchedule.mockReturnValue(
      Effect.fail({
        _tag: 'ResourceNotFoundException',
      } as ResourceNotFoundError),
)

although possibly ugly and error prone should the effect-aws library change the constants.

Different mock frameworks will have their own behaviours, but at a fundamental level, the ability to more readily construct error types would be useful.

As an aside, the service type could be exported within the service namespace, so we can avoid the Context.Tag.Service<xxx> and have something like Service.Type. I think that effect-aws could improve the exports, to better mirror those used within effect as a whole (Effect.Service exports Default as the primary layer for example).

[floydspace]

@dmeehan1968 good observations..

Example for jest/jest-mock-extended:

You can use a little more elegant mocking:

import { SchedulerService, ResourceNotFoundError } from "@effect-aws/client-scheduler";

// ...

    this.scheduler = mock<Context.Tag.Service<SchedulerService>>()

    this.scheduler.updateSchedule.mockReturnValue(
      Effect.fail(
        mock<ResourceNotFoundError>({
          _tag: "ResourceNotFoundException",
          message: "not found",
          Message: "Not Found",
        })
      ),
    )

the ResourceNotFoundError is a copy of ResourceNotFoundException (I know it is a bit wierd that it is renamed, but I though initially it would be better to make namings consistent, inspite what aws-sdk provides. But now I think it was a mistake...)

currently effect-aws copies the error and adds the _tag to it, I know it is not perfect, I'd rather keep the error instances original and add _tag in prototype: this gives benefit of using instanceof on errors as they stay native..

we can avoid the Context.Tag.Service and have something like Service.Type.

I also noticed inconviniece with that, agree, it is good to improve

I think that effect-aws could improve the exports, to better mirror those used within effect

Also agree, effect-aws was written before this service Default was introduced. in fact it is not using the Service data structure. Can be improved too..