Add a validator that checks that the lib directory is not empty.

Add a validator that checks that the lib directory is not empty.

BUG=7045
Committed: https://code.google.com/p/dart/source/detail?r=16010

[Bob Nystrom, 2012-12-12 00:11:51]

One suggestion. Otherwise LGTM.

https://codereview.chromium.org/11543006/diff/1/utils/pub/validator/lib.dart
File utils/pub/validator/lib.dart (right):

https://codereview.chromium.org/11543006/diff/1/utils/pub/validator/lib.dart#...
utils/pub/validator/lib.dart:26: errors.add('Your package must have a "lib/"
directory so users have '
In pub install, it's only a warning if you depend on a package with no lib
directory. Can it be a warning here too?

[nweiz, 2012-12-12 00:53:34]

https://codereview.chromium.org/11543006/diff/1/utils/pub/validator/lib.dart
File utils/pub/validator/lib.dart (right):

https://codereview.chromium.org/11543006/diff/1/utils/pub/validator/lib.dart#...
utils/pub/validator/lib.dart:26: errors.add('Your package must have a "lib/"
directory so users have '
On 2012/12/12 00:11:51, Bob Nystrom wrote:
> In pub install, it's only a warning if you depend on a package with no lib
> directory. Can it be a warning here too?

We decided to make this an error because there's no utility at all in publishing
a package that contains no resources and is un-importable, other than squatting
on a package name, which I don't think we want to encourage.

I thought the warning from depending on a package without a lib directory was
just a holdover from when we supported both package layouts. There's no reason
that shouldn't be an error, either.

[Bob Nystrom, 2012-12-12 01:03:56]

On 2012/12/12 00:53:34, nweiz wrote:
> https://codereview.chromium.org/11543006/diff/1/utils/pub/validator/lib.dart
> File utils/pub/validator/lib.dart (right):
> 
>
https://codereview.chromium.org/11543006/diff/1/utils/pub/validator/lib.dart#...
> utils/pub/validator/lib.dart:26: errors.add('Your package must have a "lib/"
> directory so users have '
> On 2012/12/12 00:11:51, Bob Nystrom wrote:
> > In pub install, it's only a warning if you depend on a package with no lib
> > directory. Can it be a warning here too?
> 
> We decided to make this an error because there's no utility at all in
publishing
> a package that contains no resources and is un-importable, other than
squatting
> on a package name, which I don't think we want to encourage.

OK.

> 
> I thought the warning from depending on a package without a lib directory was
> just a holdover from when we supported both package layouts. There's no reason
> that shouldn't be an error, either.

That definitely shouldn't be an error. Imagine your app uses foo which uses bar.
The latest version of bar lacks a lib dir but apparently foo isn't using it
anyway. It would be cruel for pub to not allow you to run your app just because
of that.