This pull request adds a packages resource so that we can check for pattern matches against all the packages on a system. This initially implements only dpkg support for debian-based platforms so we can cover this use case:
```ruby
describe packages(/^xserver-xorg.*/) do
its("list") { should be_empty }
end
```
This uses FilterTable so we can supply additional queries, too.
```ruby
describe packages(/vi.+/).where { status != 'installed' } do
its('statuses') { should be_empty }
end
```
Users can specify the name as a string or a regular expression. If it is a string, we will escape it and convert it to a regular expression to use in matching against the full returned list of packages. If it is a regular expression, we take that as is and use it to filter the results.
While some package management systems such as `dpkg` can take a shell glob argument to filter their results, we eschew this and require a regular expression to match multiple package names because we will need this to work across other platforms in the future. This means that the following:
```ruby
packages("vim")
```
Will return *all* the "vim" packages on the system. The `packages` resource will take `"vim"`, turn it into `/vim/`, and greedily match anything with "vim" in the name. To match only a single package named `vim`, it needs to be an anchored regular expression.
```ruby
packages(/^vim$/)
```
Signed-off-by: Joshua Timberman <joshua@chef.io>
Use entries instead of list
Added a few more tests and non installed package in output
Signed-off-by: Alex Pop <apop@chef.io>
fix lint
Signed-off-by: Alex Pop <apop@chef.io>
Signed-off-by: Joshua Timberman <joshua@chef.io>
