Support thor install <uri> to install remote thor files

The previous code suggested that this was supported, but it was not
really working as expected.

lib/thor/runner.rb

@@ -6,8 +6,6 @@
 require "pathname"
 
 class Thor::Runner < Thor #:nodoc:
-  autoload :OpenURI, "open-uri"
-
   map "-T" => :list, "-i" => :install, "-u" => :update, "-v" => :version
 
   def self.banner(command, all = false, subcommand = false)
@@ -48,22 +46,33 @@ def method_missing(meth, *args)
   def install(name) # rubocop:disable Metrics/MethodLength
     initialize_thorfiles
 
-    # If a directory name is provided as the argument, look for a 'main.thor'
-    # command in said directory.
-    begin
-      if File.directory?(File.expand_path(name))
-        base = File.join(name, "main.thor")
-        package = :directory
-        contents = open(base, &:read)
-      else
-        base = name
-        package = :file
-        contents = open(name, &:read)
+    is_uri  = name =~ %r{^https?\://}
+
+    if is_uri
+      base = name
+      package = :file
+      require "open-uri"
+      begin
+        contents = URI.send(:open, name, &:read) # Using `send` for Ruby 2.4- support
+      rescue OpenURI::HTTPError
+        raise Error, "Error opening URI '#{name}'"
+      end
+    else
+      # If a directory name is provided as the argument, look for a 'main.thor'
+      # command in said directory.
+      begin
+        if File.directory?(File.expand_path(name))
+          base = File.join(name, "main.thor")
+          package = :directory
+          contents = open(base, &:read)
+        else
+          base = name
+          package = :file
+          contents = open(name, &:read)
+        end
+      rescue Errno::ENOENT
+        raise Error, "Error opening file '#{name}'"
       end
-    rescue OpenURI::HTTPError
-      raise Error, "Error opening URI '#{name}'"
-    rescue Errno::ENOENT
-      raise Error, "Error opening file '#{name}'"
     end
 
     say "Your Thorfile contains:"
@@ -84,7 +93,7 @@ def install(name) # rubocop:disable Metrics/MethodLength
       as = basename if as.empty?
     end
 
-    location = if options[:relative] || name =~ %r{^https?://}
+    location = if options[:relative] || is_uri
       name
     else
       File.expand_path(name)

spec/runner_spec.rb

@@ -118,11 +118,11 @@ def when_no_thorfiles_exist
   end
 
   describe "commands" do
+    let(:location) { "#{File.dirname(__FILE__)}/fixtures/command.thor" }
     before do
-      @location = "#{File.dirname(__FILE__)}/fixtures/command.thor"
       @original_yaml = {
         "random" => {
-          :location  => @location,
+          :location  => location,
           :filename  => "4a33b894ffce85d7b412fc1b36f88fe0",
           :namespaces => %w(amazing)
         }
@@ -214,31 +214,53 @@ def when_no_thorfiles_exist
     end
 
     describe "install/update" do
-      before do
-        allow(FileUtils).to receive(:mkdir_p)
-        allow(FileUtils).to receive(:touch)
-        allow(Thor::LineEditor).to receive(:readline).and_return("Y")
+      context "with local thor files" do
+        before do
+          allow(FileUtils).to receive(:mkdir_p)
+          allow(FileUtils).to receive(:touch)
+          allow(Thor::LineEditor).to receive(:readline).and_return("Y")
+
+          path = File.join(Thor::Util.thor_root, Digest::MD5.hexdigest(location + "random"))
+          expect(File).to receive(:open).with(path, "w")
+        end
 
-        path = File.join(Thor::Util.thor_root, Digest::MD5.hexdigest(@location + "random"))
-        expect(File).to receive(:open).with(path, "w")
-      end
 
-      it "updates existing thor files" do
-        path = File.join(Thor::Util.thor_root, @original_yaml["random"][:filename])
-        if File.directory? path
-          expect(FileUtils).to receive(:rm_rf).with(path)
-        else
-          expect(File).to receive(:delete).with(path)
+        it "updates existing thor files" do
+          path = File.join(Thor::Util.thor_root, @original_yaml["random"][:filename])
+          if File.directory? path
+            expect(FileUtils).to receive(:rm_rf).with(path)
+          else
+            expect(File).to receive(:delete).with(path)
+          end
+          silence_warnings do
+            silence(:stdout) { Thor::Runner.start(%w(update random)) }
+          end
         end
-        silence_warnings do
-          silence(:stdout) { Thor::Runner.start(%w(update random)) }
+
+        it "installs thor files" do
+          ARGV.replace %W(install #{location})
+          silence_warnings do
+            silence(:stdout) { Thor::Runner.start }
+          end
         end
       end
 
-      it "installs thor files" do
-        ARGV.replace %W(install #{@location})
-        silence_warnings do
-          silence(:stdout) { Thor::Runner.start }
+      context "with remote thor files" do
+        let(:location) { "https://example.com/Thorfile" }
+
+        it "installs thor files" do
+          allow(Thor::LineEditor).to receive(:readline).and_return("Y", "random")
+          stub_request(:get, location).to_return(:body => "class Foo < Thor; end")
+          path = File.join(Thor::Util.thor_root, Digest::MD5.hexdigest(location + "random"))
+          expect(File).to receive(:open).with(path, "w")
+          expect { silence(:stdout) { Thor::Runner.start(%W(install #{location})) } }.not_to raise_error
+        end
+
+        it "shows proper errors" do
+          expect(Thor::Runner).to receive :exit
+          expect(URI).to receive(:open).with(location).and_raise(OpenURI::HTTPError.new("foo", StringIO.new))
+          content = capture(:stderr) { Thor::Runner.start(%W(install #{location})) }
+          expect(content).to include("Error opening URI '#{location}'")
         end
       end
     end