Add support for parent directories in `StringPath`

This support is not completed though, as parent directory that is first
in collection returned by `directories!` is not iterable yet.

app/views/projects/artifacts/_tree_directory.html.haml

 %tr{ class: 'tree-item' }
   %td.tree-item-file-name
-    = tree_icon('folder', '755', directory.basename)
+    = tree_icon('folder', '755', directory.name)
     %span.str-truncated
-      = link_to directory.basename, browse_namespace_project_build_artifacts_path(@project.namespace, @project, @build, path: directory.path)  
+      = link_to directory.name, browse_namespace_project_build_artifacts_path(@project.namespace, @project, @build, path: directory.path)
   %td

app/views/projects/artifacts/browse.html.haml

@@ -16,5 +16,5 @@
         %tr
           %th Name
           %th Download
-      = render partial: 'tree_directory', collection: @path.directories, as: :directory
+      = render partial: 'tree_directory', collection: @path.directories!, as: :directory
       = render partial: 'tree_file', collection: @path.files, as: :file

lib/gitlab/string_path.rb

@@ -5,6 +5,7 @@ module Gitlab
   # This is IO-operations safe class, that does similar job to 
   # Ruby's Pathname but without the risk of accessing filesystem.
   #
+  # TODO: better support for './' and '../'
   #
   class StringPath
     attr_reader :path, :universe
@@ -45,10 +46,13 @@ module Gitlab
     end
 
     def basename
-      name = @path.split(::File::SEPARATOR).last
       directory? ? name + ::File::SEPARATOR : name
     end
 
+    def name
+      @path.split(::File::SEPARATOR).last
+    end
+
     def has_descendants?
       descendants.any?
     end
@@ -68,6 +72,10 @@ module Gitlab
       children.select { |child| child.directory? }
     end
 
+    def directories!
+      has_parent? ? directories.prepend(new(@path + '../')) : directories
+    end
+
     def files
       return [] unless directory?
       children.select { |child| child.file? }

spec/lib/gitlab/string_path_spec.rb

@@ -50,18 +50,20 @@ describe Gitlab::StringPath do
 
   describe 'path/dir_1/', path: 'path/dir_1/' do
     subject { |example| path(example) }
-
     it { is_expected.to have_parent }
 
     describe '#basename' do
       subject { |example| path(example).basename }
-
       it { is_expected.to eq 'dir_1/' }
     end
 
+    describe '#name' do
+      subject { |example| path(example).name }
+      it { is_expected.to eq 'dir_1' }
+    end
+
     describe '#parent' do
       subject { |example| path(example).parent }
-
       it { is_expected.to eq string_path('path/') }
     end
 
@@ -101,6 +103,15 @@ describe Gitlab::StringPath do
       it { is_expected.to all(be_an_instance_of described_class) }
       it { is_expected.to contain_exactly string_path('path/dir_1/subdir/') }
     end
+
+    describe '#directories!' do
+      subject { |example| path(example).directories! }
+
+      it { is_expected.to all(be_directory) }
+      it { is_expected.to all(be_an_instance_of described_class) }
+      it { is_expected.to contain_exactly string_path('path/dir_1/subdir/'),
+                                          string_path('path/dir_1/../') }
+    end
   end
 
   describe './', path: './' do
@@ -118,7 +129,6 @@ describe Gitlab::StringPath do
 
     describe '#children' do
       subject { |example| path(example).children }
-
       it { expect(subject.count).to eq 3 }
     end
   end