Better regular expression attribute handling

[kpaulisse]

This PR solves two reported issues regarding regular expression handling and ignores.

Fixes #175. Regular expressions were not supported for attributes which explains the error that was reported. Now regular expressions are supported.

Fixes #183. The "no newline at end of file" is now ignored if it appears in BOTH the "from" and "to" diffs because it's not really a difference in that case. (If it appears in one but not the other, it's still a difference, and it would need to be explicitly ignored.)

/cc @baurmatt who reported both of these issues. Care to give this branch a try with your use cases?

[baurmatt]

Thanks a lot! :)

Regarding #183: This is fixed for my example and now works as expected.

Regarding #175:
This seems to be kind of fixed as in: it isn't throwing errors anymore. But my change still isn't ignore.
Example:

mbaur@jumphost:~ $ Sources/syseleven-control/scripts/diffenvs/diffenvs -e mbaur -n server1234 --no-puppet
I, [2018-03-28T18:06:29.231143 #26699]  INFO -- : Running diffenvs for server1234 (production <=> mbaur)
  File[/etc/apache2/mods-available/mpm_prefork.conf] =>
   parameters =>
     group =>
      + test
     mode =>
      + 0666
     owner =>
      + test
*******************************************

The ignore list is configured as following:

catalog_diff_result = OctocatalogDiff::API::V1.catalog_diff(
  {
    :to_catalog   => catalog_new.path,
    :from_catalog => catalog_old.path,
    :ignore       => [
      {
        type: Regexp.new('\AFile\z'),
        attr: Regexp.new("\Aparameters\f(owner|group|mode)\z"),
      },
    ],
  }
)

[kpaulisse]

attr: Regexp.new("\Aparameters\f(owner|group|mode)\z"),

Try this:

attr: Regexp.new("\\Aparameters\f(owner|group|mode)\\z"),

This may demonstrate what's going on:

irb(main):001:0> r = Regexp.new("\Akittens\z")
=> /Akittensz/
irb(main):002:0> r.match("kittens")
=> nil
irb(main):003:0> r = Regexp.new("\\Akittens\\z")
=> /\Akittens\z/
irb(main):004:0> r.match("kittens")
=> #<MatchData "kittens">

Edit: I've just pushed an update to the documentation to correct the examples and add this as a tip.

[baurmatt]

attr: Regexp.new("\Aparameters\f(owner|group|mode)\z"),

That does the trick. Thanks! :)

[kpaulisse]

Testing within GitHub for a couple days, then I'll merge this.