Use windows paths without case-sensitivity.ksubrama/path_space

Fixes #1684
Add tests for path manipulation in chef-fs.
Clean up the handling of paths in chef-fs.

6 files changed, 247 insertions, 91 deletions

diff --git a/lib/chef/chef_fs/config.rb b/lib/chef/chef_fs/config.rb
index 6666a3deee..40cbb36530 100644
--- a/lib/chef/chef_fs/config.rb
+++ b/lib/chef/chef_fs/config.rb
@@ -111,7 +111,7 @@ class Chef
       #
       def initialize(chef_config = Chef::Config, cwd = Dir.pwd, options = {}, ui = nil)
         @chef_config = chef_config
-        @cwd = cwd
+        @cwd = File.expand_path(cwd)
         @cookbook_version = options[:cookbook_version]
 
         if @chef_config[:repo_mode] == 'everything' && is_hosted? && !ui.nil?
@@ -166,34 +166,37 @@ class Chef
       # server_path('/home/jkeiser/chef_repo/cookbooks/blah') == '/cookbooks/blah'
       # server_path('/home/*/chef_repo/cookbooks/blah') == nil
       #
-      # If there are multiple paths (cookbooks, roles, data bags, etc. can all
-      # have separate paths), and cwd+the path reaches into one of them, we will
-      # return a path relative to that.  Otherwise we will return a path to
-      # chef_repo.
+      # If there are multiple different, manually specified paths to object locations
+      # (cookbooks, roles, data bags, etc. can all have separate paths), and cwd+the
+      # path reaches into one of them, we will return a path relative to the first
+      # one to match it.  Otherwise we expect the path provided to be to the chef
+      # repo path itself.  Paths that are not available on the server are not supported.
       #
       # Globs are allowed as well, but globs outside server paths are NOT
       # (presently) supported.  See above examples.  TODO support that.
       #
       # If the path does not reach into ANY specified directory, nil is returned.
       def server_path(file_path)
-        pwd = File.expand_path(Dir.pwd)
-        absolute_pwd = Chef::ChefFS::PathUtils.realest_path(File.expand_path(file_path, pwd))
+        target_path = Chef::ChefFS::PathUtils.realest_path(file_path, @cwd)
 
         # Check all object paths (cookbooks_dir, data_bags_dir, etc.)
+        # These are either manually specified by the user or autogenerated relative
+        # to chef_repo_path.
         object_paths.each_pair do |name, paths|
           paths.each do |path|
-            realest_path = Chef::ChefFS::PathUtils.realest_path(path)
-            if PathUtils.descendant_of?(absolute_pwd, realest_path)
-              relative_path = Chef::ChefFS::PathUtils::relative_to(absolute_pwd, realest_path)
-              return relative_path == '.' ? "/#{name}" : "/#{name}/#{relative_path}"
+            object_abs_path = Chef::ChefFS::PathUtils.realest_path(path, @cwd)
+            if relative_path = PathUtils.descendant_path(target_path, object_abs_path)
+              return Chef::ChefFS::PathUtils.join("/#{name}", relative_path)
             end
           end
         end
 
         # Check chef_repo_path
         Array(@chef_config[:chef_repo_path]).flatten.each do |chef_repo_path|
-          realest_chef_repo_path = Chef::ChefFS::PathUtils.realest_path(chef_repo_path)
-          if absolute_pwd == realest_chef_repo_path
+          # We're using realest_path here but we really don't need to - we can just expand the
+          # path and use realpath because a repo_path if provided *must* exist.
+          realest_chef_repo_path = Chef::ChefFS::PathUtils.realest_path(chef_repo_path, @cwd)
+          if Chef::ChefFS::PathUtils.os_path_eq?(target_path, realest_chef_repo_path)
             return '/'
           end
         end
@@ -201,15 +204,10 @@ class Chef
         nil
       end
 
-      # The current directory, relative to server root
+      # The current directory, relative to server root.  This is a case-sensitive server path.
+      # It only exists if the current directory is a child of one of the recognized object_paths below.
       def base_path
-        @base_path ||= begin
-          if @chef_config[:chef_repo_path]
-            server_path(File.expand_path(@cwd))
-          else
-            nil
-          end
-        end
+        @base_path ||= server_path(@cwd)
       end
 
       # Print the given server path, relative to the current directory
@@ -217,10 +215,10 @@ class Chef
         server_path = entry.path
         if base_path && server_path[0,base_path.length] == base_path
           if server_path == base_path
-            return "."
-          elsif server_path[base_path.length,1] == "/"
+            return '.'
+          elsif server_path[base_path.length,1] == '/'
             return server_path[base_path.length + 1, server_path.length - base_path.length - 1]
-          elsif base_path == "/" && server_path[0,1] == "/"
+          elsif base_path == '/' && server_path[0,1] == '/'
             return server_path[1, server_path.length - 1]
           end
         end
diff --git a/lib/chef/chef_fs/file_pattern.rb b/lib/chef/chef_fs/file_pattern.rb
index 134d22cbd5..b2351dac68 100644
--- a/lib/chef/chef_fs/file_pattern.rb
+++ b/lib/chef/chef_fs/file_pattern.rb
@@ -72,7 +72,7 @@ class Chef
       def could_match_children?(path)
         return false if path == '' # Empty string is not a path
 
-        argument_is_absolute = !!(path =~ /^#{Chef::ChefFS::PathUtils::regexp_path_separator}/)
+        argument_is_absolute = Chef::ChefFS::PathUtils::is_absolute?(path)
         return false if is_absolute != argument_is_absolute
         path = path[1,path.length-1] if argument_is_absolute
 
@@ -111,7 +111,7 @@ class Chef
       #
       # This method assumes +could_match_children?(path)+ is +true+.
       def exact_child_name_under(path)
-        path = path[1,path.length-1] if !!(path =~ /^#{Chef::ChefFS::PathUtils::regexp_path_separator}/)
+        path = path[1,path.length-1] if Chef::ChefFS::PathUtils::is_absolute?(path)
         dirs_in_path = Chef::ChefFS::PathUtils::split(path).length
         return nil if exact_parts.length <= dirs_in_path
         return exact_parts[dirs_in_path]
@@ -149,7 +149,7 @@ class Chef
       #   abc/*/def.match?('abc/foo/def') == true
       #   abc/*/def.match?('abc/foo') == false
       def match?(path)
-        argument_is_absolute = !!(path =~ /^#{Chef::ChefFS::PathUtils::regexp_path_separator}/)
+        argument_is_absolute = Chef::ChefFS::PathUtils::is_absolute?(path)
         return false if is_absolute != argument_is_absolute
         path = path[1,path.length-1] if argument_is_absolute
         !!regexp.match(path)
@@ -160,17 +160,6 @@ class Chef
         pattern
       end
 
-      # Given a relative file pattern and a directory, makes a new file pattern
-      # starting with the directory.
-      #
-      #   FilePattern.relative_to('/usr/local', 'bin/*grok') == FilePattern.new('/usr/local/bin/*grok')
-      #
-      # BUG: this does not support patterns starting with <tt>..</tt>
-      def self.relative_to(dir, pattern)
-        return FilePattern.new(pattern) if pattern =~ /^#{Chef::ChefFS::PathUtils::regexp_path_separator}/
-        FilePattern.new(Chef::ChefFS::PathUtils::join(dir, pattern))
-      end
-
     private
 
       def regexp
@@ -195,7 +184,7 @@ class Chef
 
       def calculate
         if !@regexp
-          @is_absolute = !!(@pattern =~ /^#{Chef::ChefFS::PathUtils::regexp_path_separator}/)
+          @is_absolute = Chef::ChefFS::PathUtils::is_absolute?(@pattern)
 
           full_regexp_parts = []
           normalized_parts = []
diff --git a/lib/chef/chef_fs/knife.rb b/lib/chef/chef_fs/knife.rb
index 86872dab71..9101e455f8 100644
--- a/lib/chef/chef_fs/knife.rb
+++ b/lib/chef/chef_fs/knife.rb
@@ -17,6 +17,7 @@
 #
 
 require 'chef/knife'
+require 'pathname'
 
 class Chef
   module ChefFS
@@ -63,7 +64,7 @@ class Chef
         # --chef-repo-path forcibly overrides all other paths
         if config[:chef_repo_path]
           Chef::Config[:chef_repo_path] = config[:chef_repo_path]
-          %w(acl client cookbook container data_bag environment group node role user).each do |variable_name|
+          Chef::ChefFS::Config::INFLECTIONS.each_value do |variable_name|
             Chef::Config.delete("#{variable_name}_path".to_sym)
           end
         end
@@ -98,14 +99,41 @@ class Chef
       end
 
       def pattern_arg_from(arg)
-        # TODO support absolute file paths and not just patterns?  Too much?
-        # Could be super useful in a world with multiple repo paths
-        if !@chef_fs_config.base_path && !Chef::ChefFS::PathUtils.is_absolute?(arg)
-          # Check if chef repo path is specified to give a better error message
-          ui.error("Attempt to use relative path '#{arg}' when current directory is outside the repository path")
+        inferred_path = nil
+        if Chef::ChefFS::PathUtils.is_absolute?(arg)
+          # We should be able to use this as-is - but the user might have incorrectly provided
+          # us with a path that is based off of the OS root path instead of the Chef-FS root.
+          # Do a quick and dirty sanity check.
+          if possible_server_path = @chef_fs_config.server_path(arg)
+            ui.warn("The absolute path provided is suspicious: #{arg}")
+            ui.warn("If you wish to refer to a file location, please provide a path that is rooted at the chef-repo.")
+            ui.warn("Consider writing '#{possible_server_path}' instead of '#{arg}'")
+          end
+          # Use the original path because we can't be sure.
+          inferred_path = arg
+        elsif arg[0,1] == '~'
+          # Let's be nice and fix it if possible - but warn the user.
+          ui.warn("A path relative to a user home directory has been provided: #{arg}")
+          ui.warn("Paths provided need to be rooted at the chef-repo being considered or be relative paths.")
+          inferred_path = @chef_fs_config.server_path(arg)
+          ui.warn("Using '#{inferred_path}' as the path instead of '#{arg}'.")
+        elsif Pathname.new(arg).absolute?
+          # It is definitely a system absolute path (such as C:\ or \\foo\bar) but it cannot be
+          # interpreted as a Chef-FS absolute path.  Again attempt to be nice but warn the user.
+          ui.warn("An absolute file system path that isn't a server path was provided: #{arg}")
+          ui.warn("Paths provided need to be rooted at the chef-repo being considered or be relative paths.")
+          inferred_path = @chef_fs_config.server_path(arg)
+          ui.warn("Using '#{inferred_path}' as the path instead of '#{arg}'.")
+        elsif @chef_fs_config.base_path.nil?
+          # These are all relative paths.  We can't resolve and root paths unless we are in the
+          # chef repo.
+          ui.error("Attempt to use relative path '#{arg}' when current directory is outside the repository path.")
+          ui.error("Current working directory is '#{@chef_fs_config.cwd}'.")
           exit(1)
+        else
+          inferred_path = Chef::ChefFS::PathUtils::join(@chef_fs_config.base_path, arg)
         end
-        Chef::ChefFS::FilePattern.relative_to(@chef_fs_config.base_path, arg)
+        Chef::ChefFS::FilePattern.new(inferred_path)
       end
 
       def format_path(entry)
diff --git a/lib/chef/chef_fs/path_utils.rb b/lib/chef/chef_fs/path_utils.rb
index 9ef75ce2e5..595f966378 100644
--- a/lib/chef/chef_fs/path_utils.rb
+++ b/lib/chef/chef_fs/path_utils.rb
@@ -23,31 +23,31 @@ class Chef
   module ChefFS
     class PathUtils
 
-      # If you are in 'source', this is what you would have to type to reach 'dest'
-      # relative_to('/a/b/c/d/e', '/a/b/x/y') == '../../c/d/e'
-      # relative_to('/a/b', '/a/b') == '.'
-      def self.relative_to(dest, source)
-        # Skip past the common parts
-        source_parts = Chef::ChefFS::PathUtils.split(source)
-        dest_parts = Chef::ChefFS::PathUtils.split(dest)
-        i = 0
-        until i >= source_parts.length || i >= dest_parts.length || source_parts[i] != dest_parts[i]
-          i+=1
-        end
-        # dot-dot up from 'source' to the common ancestor, then
-        # descend to 'dest' from the common ancestor
-        result = Chef::ChefFS::PathUtils.join(*(['..']*(source_parts.length-i) + dest_parts[i,dest.length-i]))
-        result == '' ? '.' : result
-      end
+      # A Chef-FS path is a path in a chef-repository that can be used to address
+      # both files on a local file-system as well as objects on a chef server.
+      # These paths are stricter than file-system paths allowed on various OSes.
+      # Absolute Chef-FS paths begin with "/" (on windows, "\" is acceptable as well).
+      # "/" is used as the path element separator (on windows, "\" is acceptable as well).
+      # No directory/path element may contain a literal "\" character.  Any such characters
+      # encountered are either dealt with as separators (on windows) or as escape
+      # characters (on POSIX systems).  Relative Chef-FS paths may use ".." or "." but
+      # may never use these to back-out of the root of a Chef-FS path.  Any such extraneous
+      # ".."s are ignored.
+      # Chef-FS paths are case sensitive (since the paths on the server are).
+      # On OSes with case insensitive paths, you may be unable to locally deal with two
+      # objects whose server paths only differ by case.  OTOH, the case of path segments
+      # that are outside the Chef-FS root (such as when looking at a file-system absolute
+      # path to discover the Chef-FS root path) are handled in accordance to the rules
+      # of the local file-system and OS.
 
       def self.join(*parts)
         return "" if parts.length == 0
         # Determine if it started with a slash
         absolute = parts[0].length == 0 || parts[0].length > 0 && parts[0] =~ /^#{regexp_path_separator}/
         # Remove leading and trailing slashes from each part so that the join will work (and the slash at the end will go away)
-        parts = parts.map { |part| part.gsub(/^\/|\/$/, "") }
+        parts = parts.map { |part| part.gsub(/^#{regexp_path_separator}+|#{regexp_path_separator}+$/, '') }
         # Don't join empty bits
-        result = parts.select { |part| part != "" }.join("/")
+        result = parts.select { |part| part != '' }.join('/')
         # Put the / back on
         absolute ? "/#{result}" : result
       end
@@ -60,36 +60,67 @@ class Chef
         Chef::ChefFS::windows? ? '[\/\\\\]' : '/'
       end
 
+      # Given a server path, determines if it is absolute.
+      def self.is_absolute?(path)
+        !!(path =~ /^#{regexp_path_separator}/)
+      end
       # Given a path which may only be partly real (i.e. /x/y/z when only /x exists,
       # or /x/y/*/blah when /x/y/z/blah exists), call File.realpath on the biggest
-      # part that actually exists.
+      # part that actually exists.  The paths operated on here are not Chef-FS paths.
+      # These are OS paths that may contain symlinks but may not also fully exist.
       #
       # If /x is a symlink to /blarghle, and has no subdirectories, then:
       # PathUtils.realest_path('/x/y/z') == '/blarghle/y/z'
       # PathUtils.realest_path('/x/*/z') == '/blarghle/*/z'
       # PathUtils.realest_path('/*/y/z') == '/*/y/z'
-      def self.realest_path(path)
-        path = Pathname.new(path)
-        begin
-          path.realpath.to_s
-        rescue Errno::ENOENT
-          dirname = path.dirname
-          if dirname
-            PathUtils.join(realest_path(dirname), path.basename.to_s)
-          else
-            path.to_s
+      #
+      # TODO: Move this to wherever util/path_helper is these days.
+      def self.realest_path(path, cwd = Dir.pwd)
+        path = File.expand_path(path, cwd)
+        parent_path = File.dirname(path)
+        suffix = []
+
+        # File.dirname happens to return the path as its own dirname if you're
+        # at the root (such as at \\foo\bar, C:\ or /)
+        until parent_path == path do
+          # This can occur if a path such as "C:" is given.  Ruby gives the parent as "C:."
+          # for reasons only it knows.
+          raise ArgumentError "Invalid path segment #{path}" if parent_path.length > path.length
+          begin
+            path = File.realpath(path)
+            break
+          rescue Errno::ENOENT
+            suffix << File.basename(path)
+            path = parent_path
+            parent_path = File.dirname(path)
           end
         end
+        File.join(path, *suffix.reverse)
       end
 
-      def self.descendant_of?(path, ancestor)
-        path[0,ancestor.length] == ancestor &&
-          (ancestor.length == path.length || path[ancestor.length,1] =~ /#{PathUtils.regexp_path_separator}/)
+      # Compares two path fragments according to the case-sentitivity of the host platform.
+      def self.os_path_eq?(left, right)
+        Chef::ChefFS::windows? ? left.casecmp(right) == 0 : left == right
       end
 
-      def self.is_absolute?(path)
-        path =~ /^#{regexp_path_separator}/
+      # Given two general OS-dependent file paths, determines the relative path of the
+      # child with respect to the ancestor.  Both child and ancestor must exist and be
+      # fully resolved - this is strictly a lexical comparison.  No trailing slashes
+      # and other shenanigans are allowed.
+      #
+      # TODO: Move this to util/path_helper.
+      def self.descendant_path(path, ancestor)
+        candidate_fragment = path[0, ancestor.length]
+        return nil unless PathUtils.os_path_eq?(candidate_fragment, ancestor)
+        if ancestor.length == path.length
+          ''
+        elsif path[ancestor.length,1] =~ /#{PathUtils.regexp_path_separator}/
+          path[ancestor.length+1..-1]
+        else
+          nil
+        end
       end
+
     end
   end
 end
diff --git a/spec/integration/knife/chef_repo_path_spec.rb b/spec/integration/knife/chef_repo_path_spec.rb
index 874b33901f..908657e5f7 100644
--- a/spec/integration/knife/chef_repo_path_spec.rb
+++ b/spec/integration/knife/chef_repo_path_spec.rb
@@ -24,6 +24,8 @@ describe 'chef_repo_path tests', :workstation do
   include IntegrationSupport
   include KnifeSupport
 
+  let(:error_rel_path_outside_repo) { /^ERROR: Attempt to use relative path '' when current directory is outside the repository path/ }
+
   # TODO alternate repo_path / *_path
   context 'alternate *_path' do
     when_the_repository 'has clients and clients2, cookbooks and cookbooks2, etc.' do
@@ -109,14 +111,14 @@ EOM
         context 'when cwd is at the top level' do
           before { cwd '.' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
         context 'when cwd is inside the data_bags directory' do
           before { cwd 'data_bags' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
@@ -192,14 +194,14 @@ EOM
         context 'when cwd is inside the data_bags directory' do
           before { cwd 'data_bags' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
         context 'when cwd is inside chef_repo2' do
           before { cwd 'chef_repo2' }
           it 'knife list -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
@@ -225,14 +227,14 @@ EOM
         context 'when cwd is at the top level' do
           before { cwd '.' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
         context 'when cwd is inside the data_bags directory' do
           before { cwd 'data_bags' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
@@ -445,7 +447,7 @@ EOM
         context 'when cwd is at the top level' do
           before { cwd '.' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
@@ -621,14 +623,14 @@ EOM
         context 'when cwd is at the top level' do
           before { cwd '.' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
         context 'when cwd is inside the data_bags directory' do
           before { cwd 'data_bags' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
@@ -782,7 +784,7 @@ EOM
         context 'when cwd is at the top level' do
           before { cwd '.' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
 
@@ -823,7 +825,7 @@ EOM
         context 'when cwd is inside chef_repo2/data_bags' do
           before { cwd 'chef_repo2/data_bags' }
           it 'knife list --local -Rfp fails' do
-            knife('list --local -Rfp').should_fail("ERROR: Attempt to use relative path '' when current directory is outside the repository path\n")
+            knife('list --local -Rfp').should_fail(error_rel_path_outside_repo)
           end
         end
       end
diff --git a/spec/unit/chef_fs/path_util_spec.rb b/spec/unit/chef_fs/path_util_spec.rb
new file mode 100644
index 0000000000..42eb126dfb
--- /dev/null
+++ b/spec/unit/chef_fs/path_util_spec.rb
@@ -0,0 +1,108 @@
+#
+# Author:: Kartik Null Cating-Subramanian (<ksubramanian@chef.io>)
+# Copyright:: Copyright (c) 2015 Opscode, Inc.
+# License:: Apache License, Version 2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+require 'spec_helper'
+require 'chef/chef_fs/path_utils'
+
+describe Chef::ChefFS::PathUtils do
+  context 'invoking join' do
+    it 'joins well-behaved distinct path elements' do
+      expect(Chef::ChefFS::PathUtils.join('a', 'b', 'c')).to eq('a/b/c')
+    end
+
+    it 'strips extraneous slashes in the middle of paths' do
+      expect(Chef::ChefFS::PathUtils.join('a/', '/b', '/c/')).to eq('a/b/c')
+      expect(Chef::ChefFS::PathUtils.join('a/', '/b', '///c/')).to eq('a/b/c')
+    end
+
+    it 'preserves the whether the first element was absolute or not' do
+      expect(Chef::ChefFS::PathUtils.join('/a/', '/b', 'c/')).to eq('/a/b/c')
+      expect(Chef::ChefFS::PathUtils.join('///a/', '/b', 'c/')).to eq('/a/b/c')
+    end
+  end
+
+  context 'invoking is_absolute?' do
+    it 'confirms that paths starting with / are absolute' do
+      expect(Chef::ChefFS::PathUtils.is_absolute?('/foo/bar/baz')).to be true
+      expect(Chef::ChefFS::PathUtils.is_absolute?('/foo')).to be true
+    end
+
+    it 'confirms that paths starting with // are absolute even though that looks like some windows network path' do
+      expect(Chef::ChefFS::PathUtils.is_absolute?('//foo/bar/baz')).to be true
+    end
+
+    it 'confirms that root is indeed absolute' do
+      expect(Chef::ChefFS::PathUtils.is_absolute?('/')).to be true
+    end
+
+    it 'confirms that paths starting without / are relative' do
+      expect(Chef::ChefFS::PathUtils.is_absolute?('foo/bar/baz')).to be false
+      expect(Chef::ChefFS::PathUtils.is_absolute?('a')).to be false
+    end
+
+    it 'returns false for an empty path.' do
+      expect(Chef::ChefFS::PathUtils.is_absolute?('')).to be false
+    end
+  end
+
+  context 'invoking realest_path' do
+    let(:good_path) { File.dirname(__FILE__) }
+    let(:parent_path) { File.dirname(good_path) }
+
+    it 'handles paths with no wildcards or globs' do
+      expect(Chef::ChefFS::PathUtils.realest_path(good_path)).to eq(File.expand_path(good_path))
+    end
+
+    it 'handles paths with .. and .' do
+      expect(Chef::ChefFS::PathUtils.realest_path(good_path+'/../.')).to eq(File.expand_path(parent_path))
+    end
+
+    it 'handles paths with *' do
+      expect(Chef::ChefFS::PathUtils.realest_path(good_path + '/*/foo')).to eq(File.expand_path(good_path + '/*/foo'))
+    end
+
+    it 'handles directories that do not exist' do
+      expect(Chef::ChefFS::PathUtils.realest_path(good_path + '/something/or/other')).to eq(File.expand_path(good_path + '/something/or/other'))
+    end
+
+    it 'handles root correctly' do
+      if Chef::Platform.windows?
+        expect(Chef::ChefFS::PathUtils.realest_path('C:/')).to eq('C:/')
+      else
+        expect(Chef::ChefFS::PathUtils.realest_path('/')).to eq('/')
+      end
+    end
+  end
+
+  context 'invoking descendant_path' do
+    it 'handles paths with various casing on windows' do
+      allow(Chef::ChefFS).to receive(:windows?) { true }
+      expect(Chef::ChefFS::PathUtils.descendant_path('C:/ab/b/c', 'C:/AB/B')).to eq('c')
+      expect(Chef::ChefFS::PathUtils.descendant_path('C:/ab/b/c', 'c:/ab/B')).to eq('c')
+    end
+
+    it 'returns nil if the path does not have the given ancestor' do
+      expect(Chef::ChefFS::PathUtils.descendant_path('/D/E/F', '/A/B/C')).to be_nil
+      expect(Chef::ChefFS::PathUtils.descendant_path('/A/B/D', '/A/B/C')).to be_nil
+    end
+
+    it 'returns blank if the ancestor equals the path' do
+      expect(Chef::ChefFS::PathUtils.descendant_path('/A/B/D', '/A/B/D')).to eq('')
+    end
+  end
+end