[CO-417] Add more friendly 415 Unsupported Media Type error

[paweljakubas]

Description

Implement more friendly 415 Unsupported Media Type error.

BEFORE

$ curl -X POST -vk -H "Content-Type: patate" http://localhost:8090/api/v1/wallets 

> POST /api/v1/wallets HTTP/1.1
> Host: localhost:8090
> User-Agent: curl/7.60.0
> Accept: */*
> Content-Type: patate
> 
< HTTP/1.1 415 Unsupported Media Type
< Transfer-Encoding: chunked
< Date: Fri, 05 Oct 2018 08:57:20 GMT
< Server: Warp/3.2.22
< 
* Connection #0 to host localhost left intact

AFTER

$ curl -X POST -vk -H "Content-Type: patate" http://localhost:8090/api/v1/wallets

> POST /api/v1/wallets HTTP/1.1
> Host: localhost:8090
> User-Agent: curl/7.60.0
> Accept: */*
> Content-Type: patate
> 
< HTTP/1.1 415 Unsupported Media Type
< Transfer-Encoding: chunked
< Date: Mon, 08 Oct 2018 13:14:42 GMT
< Server: Warp/3.2.22
< Content-Type: application/json
< 
* Connection #0 to host localhost left intact
{"status":"error","diagnostic":{"mimeContentTypeError":"The API expects the Content-Type's main MIME-type to be 'application/json'"},"message":"UnsupportedMimeTypePresent"}

Linked issue

https://iohk.myjetbrains.com/youtrack/issue/CO-417

Type of change

• 🐞 Bug fix (non-breaking change which fixes an issue)
• 🛠 New feature (non-breaking change which adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)
• 🏭 Refactoring that does not change existing functionality but does improve things like code readability, structure etc
• 🔨 New or improved tests for existing code
• ⛑ git-flow chore (backport, hotfix, etc)

Developer checklist

• I have read the style guide document, and my code follows the code style of this project.
• If my code deals with exceptions, it follows the guidelines.
• I have updated any documentation accordingly, if needed. Documentation changes can be reflected in opening a PR on cardanodocs.com, amending the inline Haddock comments, any relevant README file or one of the document listed in the docs directory.
• CHANGELOG entry has been added and is linked to the correct PR on GitHub.

Testing checklist

• I have added tests to cover my changes.
• All new and existing tests passed.

QA Steps

1. Run cluster and

curl -X POST -vk -H "Content-Type: patate" http://localhost:8090/api/v1/wallets

Screenshots (if available)

[paweljakubas]

continuous-integration/appveyor/pr — AppVeyor build failed because of timeout

[KtorZ]

Sorry for the late review!

[KtorZ]

Let's have it as a middleware instead, don't you think? And, let's re-use code actually serializing jsend errors toJSON

unsupportedMimeTypeMiddleware :: Middleware
unsupportedMimeTypeMiddleware = ifResponse ((== status415) . responseStatus) $ responseBuilder status415
    [ ("Content-Type", "application/json") ]
    (fromByteString . toStrict . encode UnsupportedMimeTypeError

Something along those lines, with UnsupportedMimeTypeError defined somewhere as a plain type, like other errors, not forgetting the example documentation in Swagger.hs ❤️

[paweljakubas]

Made changes as requested:

1. Introduced UnsupportedMimeTypeError
2. Encapsulated the stuff inside middleware
3. Added golden test, swagger entry and corresponding aesonRoundtripProp

Now it outputs:

{"status":"error","diagnostic":{"mimeContentTypeError":"The API expects the Content-Type's main MIME-type to be 'application/json'"},"message":"UnsupportedMimeTypePresent"}

Code rebased, and squashed

[paweljakubas]

Both AppVeyor failures are due to timeouts

[KtorZ]

A minor comment, but looks good now 👍

[KtorZ]

Since responseModifier is solely related to the above function, it would make sense to have it under a where clause. It doesn't make sense to use responseModifier as it is in any other context 👍

[KtorZ]

May you add an entry in the CHANGELOG, explaining that we now have more developer-friendly errors for wrong content-type ?

Incidentally, that is a breaking change 🙃 ...

[KtorZ]

I think this should display what get passed as Text to the UnsupportedMimeTypePresent constructor ? Don't you think?

[KtorZ]

❤️

[paweljakubas]

Changes:

1. Added entry to CHANGELOG.md
2. Refactored instance Buildable UnsupportedMimeTypeError
3. Moved responseModifier into where

Commits squashed, was up to date against develop

[KtorZ]

LGTM 👍