Allow but filter out empty strings in build_dn

[ehelms]

There exists the possibility a parameter passed to build_dn could be an empty string which breaks the previous requirement on a string of length at least one, String[1]. Change to accept any length string but if the string happens to be empty, filter it out of the calculation.

[ekohl]

I'm fine either way, let me know if you think my suggestion may be better.

[ekohl]

I think this is more expressive in what it tries to achieve:

Suggested change

	options_with_values = options.filter { |_key, value| !value.nil? && value != '' }
	options_with_values = options.delete_if { |_key, value| value.nil? || value == '' }

I admit Ruby is always a bit weird since there's multiple ways of doing things. For example filter is an alias for select.

[ehelms]

I think if we use delete_if it becomes:

  options.delete_if { |_key, value| value.nil? || value == '' }

My understanding reading the docs on it is that it's an in place modifier.

[ehelms]

And testing, this actually leads to an error:

        expected katello::build_dn([["a", nil], ["b", "2"]]) to have returned "b=2" instead of raising FrozenError(can't modify frozen Array: [["a", nil], ["b", "2"]])
        /home/ehelms/workspace/upstream/installer/puppet-katello/spec/fixtures/modules/katello/lib/puppet/functions/katello/build_dn.rb:17:in `delete_if'

So based on that I'll keep it as is.

[ekohl]

That makes sense, thanks.

Though I think you should use select instead of filter for Ruby 2.5 support:

  Evaluation Error: Error while evaluating a Function Call, undefined method `filter' for #<Array:0x0000561f726d9560> (file: /home/runner/work/puppet-katello/puppet-katello/spec/fixtures/modules/katello/manifests/application.pp, line: 40, column: 24) on node fv-az572-767.xfljd2mj00zetb5gvhv1u2zrtd.dx.internal.cloudapp.net