feat: warn users about missing LICENSE

[Andrewnt219]

Motivation

Fixes #603

When the code fails to automatically detect a LICENSE file, it now warns the users if they want to continue.

Test Plan

Run vsce package without a LICENSE should generate a warning message.

# No LICENSE. 
# No 'SEE LICENSE IN term.md'

PS C:\helloworld> vsce package
Executing prepublish script 'npm run vscode:prepublish'...

> helloworld@0.0.1 vscode:prepublish
> npm run compile


> helloworld@0.0.1 compile
> tsc -p ./

 WARNING LICENSE.md or LICENSE.txt not found
Do you want to continue? [Y/N]

# No LICENSE. 
# Has 'SEE LICENSE IN term.md'

PS C:\helloworld> vsce package
Executing prepublish script 'npm run vscode:prepublish'...

> helloworld@0.0.1 vscode:prepublish
> npm run compile


> helloworld@0.0.1 compile
> tsc -p ./

 WARNING  term.md not found
Do you want to continue? [Y/N]

# Has LICENSE. 
# Has 'SEE LICENSE IN term.md'

PS C:\helloworld> vsce package
Executing prepublish script 'npm run vscode:prepublish'...

> helloworld@0.0.1 vscode:prepublish
> npm run compile


> helloworld@0.0.1 compile
> tsc -p ./

 WARNING  term.md not found
Do you want to continue? [Y/N]

[joaomoreno]

I have read through the README, but I don't know how I can set up dev environment to reporuce the case.

Yeah, the current steps seems to be broken. I've fixed those in main.

[Andrewnt219]

@joaomoreno I have resolved those issues you mentioned.

Just a bit uncertain about the LICENSE name. Do you want me to extract that matching logic into a private method of LicenseProcessor, and use that in both the construct and onEnd? Or just keep it that way?

[joaomoreno]

Yeah I would store that into a private expectedLicenseName: string property, in the ctor, so we don't have to compute it again.

[Andrewnt219]

Done. You can refer to the Test Plan for sample console output.

[Andrewnt219]

Somehow, the last commit removed some brackets from the method onFile above it, which made some tests failed. I fixed it.

[Andrewnt219]

ah, it is because of the dot in LICENSE.md or LICENSE.txt. I'll revert the regex of default back to the original.

[joaomoreno]

Added a few more commits on top.

[joaomoreno]

Thanks!

[Andrewnt219]

@joaomoreno No problem. I'd also be really happy if you can label this PR as hacktoberfest-accepted 😀.

[lnicola]

I'm not sure how this is supposed to work, but if the license is already defined as a SPDX string in package.json, the (previous) code still looked for a file on disk. Is that intentional?

[joaomoreno]

@lnicola The SPDX string only changes the licence file name to look for. It will always look for a license file.