Make it easier to detect unsupported formats

[nulltoken]

User story.
As a API Manager, I can easily distinguish that some of the files I'm trying to lint are unfit, so that I can refine my selection process (if I'm blindly globbing too widely) or even fix my files (would that be required).

Given the following file

nope.yaml:

%YAML 1.2
---
openapi: 30.0

nope: indeed

Running Spectral against it provides me with a less than rich experience an experience that could be greatly improved 😉

$ yarn spectral lint ./nope.yaml
No errors or warnings found!

Done in 1.30s.

Indeed, I may think that my file is perfect and that it passed all the many built-in checks Spectral comes up with.

Whereas the sad reality is that it went through NO rule at all.

Spectral cli only hints when a supported format is found.

This might become a bit more confusing now that Spectral accepts multiple paths and even globs.

Describe the solution you'd like

I'd really like to turn that into a positive visual indicator for the user. One idea would be to turn this into a "rule-like" feedback (that the user could optionally control through a ruleset (silencing it or raising its default severity error, for instance))

$ yarn spectral lint ./nope.yaml
c:/nope.yaml
  1:1   info  unrecognized-format   Provided file format doesn't match any of the built-in validator

✖ 1 problem (0 errors, 0 warnings, 1 infos)

Embedded free bonus point: Getting this feedback trough the standard pipeline would seamlessly feed the new JUnit formatter.

Additional context

An 🍎 a day keeps the 👨‍⚕️ away