Test empty strings arguments to path.join().

Test empty strings arguments to path.join().

BUG=https://code.google.com/p/dart/issues/detail?id=11819
R=nweiz@google.com, whesse@google.com

Committed: https://code.google.com/p/dart/source/detail?r=25033

[Bob Nystrom, 2013-07-15 15:51:30]

It looks like path is already doing what I expect here (which is what Python
does, but not what Ruby does), so the code is OK. But #11819 brought to my
attention that we don't have any tests for this.

Now we do. :)

[Bill Hesse, 2013-07-15 17:05:07]

LGTM, except that it does not test
join('a', 'b', ''), which I think should be 'a/b/'.
Or if it should be 'a/b', then what is the expected way to
add a path separator to the end of path?  Is it instead:

join('a', 'b$separator')?
or 
join('a', 'b', separator)?

Whichever what it is done, there should be tests for it.

[nweiz, 2013-07-15 19:40:00]

LGTM

On 2013/07/15 17:05:07, Bill Hesse wrote:
> LGTM, except that it does not test
> join('a', 'b', ''), which I think should be 'a/b/'.
> Or if it should be 'a/b', then what is the expected way to
> add a path separator to the end of path?  Is it instead:
> 
> join('a', 'b$separator')?
> or 
> join('a', 'b', separator)?
> 
> Whichever what it is done, there should be tests for it.

I think join('a', 'b', '') should be 'a/b'. I don't think we want to treat '' as
an entry with an empty name (which is borne out by join('a', '', 'b') not
returning 'a//b'); we should treat it as no entry at all.

I think join('a', 'b$separator') is fine for producing 'a/b/'. Since it's not
semantically distinct from 'a/b', there's not much need to make it easy to
generate.

[Bob Nystrom, 2013-07-15 19:58:19]

On 2013/07/15 19:40:00, nweiz wrote:
> LGTM
> 
> On 2013/07/15 17:05:07, Bill Hesse wrote:
> > LGTM, except that it does not test
> > join('a', 'b', ''), which I think should be 'a/b/'.
> > Or if it should be 'a/b', then what is the expected way to
> > add a path separator to the end of path?  Is it instead:
> > 
> > join('a', 'b$separator')?
> > or 
> > join('a', 'b', separator)?
> > 
> > Whichever what it is done, there should be tests for it.
> 
> I think join('a', 'b', '') should be 'a/b'. I don't think we want to treat ''
as
> an entry with an empty name (which is borne out by join('a', '', 'b') not
> returning 'a//b'); we should treat it as no entry at all.

Yeah, this feels right to me too.

Uploaded a new patch that tests that. It actually wasn't behaving that way right
now. PTAL.

[nweiz, 2013-07-15 23:28:14]

lgtm

[Bob Nystrom, 2013-07-15 23:28:56]

Committed patchset #2 manually as r25033 (presubmit successful).