Correct root path representation.

Assisted-By: devx/cbdeae41-9308-4071-ad53-58cd92db2946

Author: samuel-williams-shopify

lib/utopia/path.rb

@@ -15,7 +15,12 @@ class Path
 		# Initialize a path from its individual components.
 		# @parameter components [Array(String)] The path components, including empty components that denote leading or trailing separators.
 		def initialize(components = [])
-			@components = components
+			# An absolute root includes both its leading and trailing separators:
+			if components == [""]
+				@components = ["", ""]
+			else
+				@components = components
+			end
 		end
 
 		attr_accessor :components
@@ -39,7 +44,7 @@ def empty?
 		# Construct the root path.
 		# @returns [Path] The root path.
 		def self.root
-			self.new([""])
+			self.new(["", ""])
 		end
 
 		# Compute the number of leading components shared by two sequences.
@@ -63,8 +68,14 @@ def self.shortest_path(path, root)
 
 			# The difference between the root path and the required path, taking into account the common prefix:
 			up = root.components.size - i
+			down = path.components[i..-1]
 
-			return self.create([".."] * up + path.components[i..-1])
+			# A parent component already denotes the destination directory, so a trailing directory separator is redundant:
+			if up > 0 && down == [""]
+				down = []
+			end
+			
+			return self.create([".."] * up + down)
 		end
 
 		# Compute the shortest relative path from the containing directory of `root` to this path.
@@ -212,23 +223,14 @@ def to_relative!
 		# Convert this object to a string.
 		# @returns [String] The resulting string.
 		def to_str
-			if @components == [""]
-				SEPARATOR
-			else
-				@components.join(SEPARATOR)
-			end
+			@components.join(SEPARATOR)
 		end
 
 		alias to_s to_str
 
 		# Encode this application path as a URL path.
 		# @returns [Protocol::URL::Path] The encoded URL path.
 		def to_url_path
-			# Preserve Utopia's compact representation of the absolute root:
-			if @components == [""]
-				return Protocol::URL::Path[SEPARATOR]
-			end
-			
 			return Protocol::URL::Path.for(
 				@components,
 				encoding: Protocol::URL::Encoding::System,
@@ -348,20 +350,27 @@ def first
 		# Return the last path component, excluding the root marker.
 		# @returns [String | Nil] The last component.
 		def last
-			if @components != [""]
-				@components.last
-			end
+			@components.last
 		end
 
 		alias last? file?
 
 		# Remove the last path component without converting the root path to a relative path.
 		# @returns [String | Nil] The removed component.
 		def pop
-			# We don't want to convert an absolute path to a relative path.
-			if @components != [""]
-				@components.pop
+			# The absolute root has no path component to remove:
+			if @components == ["", ""]
+				return nil
 			end
+			
+			component = @components.pop
+			
+			# Preserve the canonical absolute root after removing its final component:
+			if @components == [""]
+				@components << ""
+			end
+			
+			return component
 		end
 
 		# @returns [String] The last path component without its file extension.
@@ -482,6 +491,11 @@ def == other
 		# @parameter other [Path] The possible prefix.
 		# @returns [Boolean] Whether this path starts with all components of `other`.
 		def start_with? other
+			# The root directory contains every absolute path:
+			if other.components == ["", ""]
+				return absolute?
+			end
+			
 			other.components.each_with_index do |part, index|
 				return false if @components[index] != part
 			end

test/utopia/path.rb

@@ -23,10 +23,12 @@
 		let(:path) {subject.root}
 
 		it "is a root path" do
-			expect(path).to be == [""]
+			expect(path).to be == ["", ""]
+			expect(path).to be == subject.create("/")
+			expect(path).not.to be == subject.create("")
 			expect(path).not.to be(:relative?)
 			expect(path).to be(:absolute?)
-			expect(path).to have_attributes(local_path: be == "")
+			expect(path).to have_attributes(local_path: be == "/")
 		end
 	end
 
@@ -120,7 +122,7 @@
 			let(:path) {subject.root}
 
 			it "can extract the last path component from a a root path" do
-				expect(path.last).to be == nil
+				expect(path.last).to be == ""
 			end
 		end
 
@@ -131,6 +133,22 @@
 		end
 	end
 
+	with "#pop" do
+		it "does not remove the absolute root" do
+			path = Utopia::Path.root
+			
+			expect(path.pop).to be_nil
+			expect(path).to be == Utopia::Path.root
+		end
+		
+		it "preserves the absolute root after removing the final component" do
+			path = Utopia::Path["/foo"]
+			
+			expect(path.pop).to be == "foo"
+			expect(path).to be == Utopia::Path.root
+		end
+	end
+	
 	with "#+" do
 		it "can add root path as string" do
 			root = Utopia::Path["/invoices/_template"]
@@ -173,7 +191,7 @@
 
 		descendants = root.descend.to_a
 
-		expect(descendants[0].components).to be == [""]
+		expect(descendants[0].components).to be == ["", ""]
 		expect(descendants[1].components).to be == ["", "foo"]
 		expect(descendants[2].components).to be == ["", "foo", "bar"]
 
@@ -224,6 +242,18 @@
 		expect(path.start_with?(path.dirname)).to be == true
 	end
 
+	it "should start with the absolute root" do
+		path = Utopia::Path["/a/b/c/d/e"]
+		
+		expect(path.start_with?(Utopia::Path.root)).to be == true
+	end
+	
+	it "should preserve the absolute root when taking the directory name" do
+		path = Utopia::Path["/foo"]
+		
+		expect(path.dirname).to be == Utopia::Path.root
+	end
+	
 	it "should split at the specified point" do
 		path = Utopia::Path["/a/b/c/d/e"]
 
@@ -287,6 +317,13 @@
 		expect((output + short).simplify).to be == input
 	end
 
+	it "should omit a redundant root separator when ascending to a parent directory" do
+		input = Utopia::Path.root
+		output = Utopia::Path["/nested/index"]
+		
+		expect(input.shortest_path(output)).to be == Utopia::Path[".."]
+	end
+	
 	with "#simplify" do
 		it "doesn't remove leading .. from relative paths" do
 			path = Utopia::Path["../foo/bar"]