Validate Command for Piral Instance

[FlorianRappl]

Description

Right now the Piral instance is checked in a shallow way to obey to the requirements / spec, e.g., if an app key is present (and valid) in the package.json.

This should go a bit further and the validation should also be exposed in form of a Piral CLI command, such as piral validate.

Background

If the information, e.g., in files is invalid it should be pointed out before scaffolding / running pilet debug or similar is tried. It should complain as soon as possible.

Discussion

What should be verified? Initial guess:

• package.json content w.r.t. Piral, such as the app field, pilets section etc.
• All related files, e.g., if the files in pilets.files are valid paths and in case of app have a valid content
• Potentially some consistency checks (which ones?)

[SantoJambit]

• If a pilets.files directory entry contains subdirectories, issue a warning that it will be shallowly copied?
• If a pilet.files entry contains a .gitignore file (or other file that is not published to npm), issue an error?
• If a pilet.files entry exists, that is not specified in files or maybe specified in .npmignore (i.e. doesn't get published), issue an error?
• Ensure that exported/external dependencies are listed in "dependencies", i.e. not in "devDependencies".
• Maybe a simple schema validation for the pilets part of package.json?

[FlorianRappl]

If a pilets.files directory entry contains subdirectories, issue a warning that it will be shallowly copied?

But that would be rather hostile, right? I mean its the default behavior to leave this out / make a shallow copy (which may be totally desirable). We can make an info output (leaving out "x" files from the subdirectories of) to hint in that direction.

Yep, rest sounds very good - thanks a lot for the fruitful input @SantoJambit !

[FlorianRappl]

Landed in develop.