fix: reply all files and directries within the folders defined in root

[is2ei]

Fixes #203

Checklist

• run npm run test and npm run benchmark
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[Eomm]

This feature is not documented or do I overlook it?

What is going to happen when the same file name is in both directories?

[Eomm]

Suggested change

	entries = await Promise.all(dir.map(async (d) => await dirList.list(d, options)))
	entries = await Promise.all(dir.map((d) => dirList.list(d, options)))

[is2ei]

@Eomm
Thanks for your comment.
I found my change would produce an inconsistency.
I created some examples.

Let's say we have some directories like this:

$ tree test/static3/
test/static3/
├── dir1
│   ├── hello.html
│   └── inner
│       └── index.html
└── dir2
    ├── hello.html
    ├── index.html
    ├── inner
    └── world.html

4 directories, 5 files

Then, the test below will pass.

t.test('dir list adopts first found dir when the root is an array', t => {
  t.plan(2)

  const options = {
    root: [path.join(__dirname, '/static3/dir1'), path.join(__dirname, '/static3/dir2')],
    prefix: '/public',
    index: false,
    list: true
  }

  const route = '/public/'
  const content = { dirs: ['inner'], files: ['hello.html'] }

  helper.arrange(t, options, (url) => {
    t.test(route, t => {
      t.plan(3)
      simple.concat({
        method: 'GET',
        url: url + route
      }, (err, response, body) => {
        t.error(err)
        t.equal(response.statusCode, 200)
        t.equal(body.toString(), JSON.stringify(content))
      })
    })
  })
})

Also, the test below also passes.

t.test('reply all files and directories when root is an array', t => {
  t.plan(2)
  const options = {
    root: [path.join(__dirname, '/static3/dir1'), path.join(__dirname, '/static3/dir2')],
    prefix: '/public',
    list: {
      format: 'json',
      names: ['index.json']
    }
  }
  const route = '/public/index.json'
  const content = { dirs: ['inner', 'inner'], files: ['hello.html', 'hello.html', 'world.html'] }

  helper.arrange(t, options, (url) => {
    t.test(route, t => {
      t.plan(3)
      simple.concat({
        method: 'GET',
        url: url + route
      }, (err, response, body) => {
        t.error(err)
        t.equal(response.statusCode, 200)
        t.equal(body.toString(), JSON.stringify(content))
      })
    })
  })
})

The root options are the same, but the results are different. So I'd like to update my change.

[is2ei]

@Eomm
Sorry for the late reply. I updated the change. Could you review it again?

[Eomm]

This statement does not apply to the least astonishment principale.

The user would expect that the array should be processed, but it is not

I think we have two options:

1. manage the array
2. throw an error as multi-root is not supported

[is2ei]

@Eomm

Thanks.

I guess option No. 2 would be nice because the directory listing feature would be confusing if it supports multiple root. So, I'd like to add validation to the validateOptions function.

[is2ei]

@Eomm

I updated it. Could you review it again?

[mcollina]

lgtm