Move the directory maker into RSpec::Support

lib/rspec/support/directory_maker.rb

@@ -0,0 +1,32 @@
+module RSpec::Support
+  # @api private
+  #
+  # Replacement for fileutils#mkdir_p because we don't want to require parts
+  # of stdlib in RSpec.
+  class DirectoryMaker
+    # @api private
+    #
+    # Implements nested directory construction
+    def self.mkdir_p(path)
+      stack = path.start_with?(File::SEPARATOR) ? File::SEPARATOR : "."
+      path.split(File::SEPARATOR).each do |part|
+        stack = File.join(stack, part)
+
+        begin
+          unless directory_exists?(stack)
+            Dir.mkdir(stack)
+          end
+        rescue Errno::ENOTDIR
+          raise Errno::EEXIST.new($!.message)
+        end
+
+      end
+    end
+
+    private
+
+    def self.directory_exists?(dirname)
+      File.exist?(dirname) && File.directory?(dirname)
+    end
+  end
+end

lib/rspec/support/spec.rb

@@ -3,6 +3,7 @@
 RSpec::Support.require_rspec_support "spec/with_isolated_stderr"
 RSpec::Support.require_rspec_support "spec/stderr_splitter"
 RSpec::Support.require_rspec_support "spec/formatting_support"
+RSpec::Support.require_rspec_support "spec/with_isolated_directory"
 
 warning_preventer = $stderr = RSpec::Support::StdErrSplitter.new($stderr)
 

lib/rspec/support/spec/with_isolated_directory.rb

@@ -0,0 +1,9 @@
+require 'tmpdir'
+
+RSpec.shared_context "isolated directory", :isolated_directory => true do
+  around do |ex|
+    Dir.mktmpdir do |tmp_dir|
+      Dir.chdir(tmp_dir, &ex)
+    end
+  end
+end

spec/rspec/support/directory_maker_spec.rb

@@ -0,0 +1,58 @@
+require "spec_helper"
+require "fileutils"
+
+RSpec::Support.require_rspec_support("directory_maker")
+
+module RSpec::Support
+  describe DirectoryMaker do
+    shared_examples_for "an mkdir_p implementation" do
+      include_context "isolated directory"
+
+      let(:dirname) { File.join(%w[tmp a recursive structure]) }
+
+      def directory_exists?(dirname)
+        File.exist?(dirname) && File.directory?(dirname)
+      end
+
+      it "makes directories recursively" do
+        mkdir_p.call(dirname)
+        expect(directory_exists?(dirname)).to be true
+      end
+
+      it "does not raise if the directory already exists" do
+        Dir.mkdir("tmp")
+        mkdir_p.call(dirname)
+        expect(directory_exists?(dirname)).to be true
+      end
+
+      context "when a file already exists" do
+        before { File.open("tmp", "w") }
+
+        it "raises, as it can't make the directory" do
+          expect {
+            mkdir_p.call(dirname)
+          }.to raise_error(Errno::EEXIST)
+        end
+      end
+
+      context "when the path specified is absolute" do
+        let(:dirname) { "bees/ponies" }
+
+        it "makes directories recursively" do
+          mkdir_p.call(File.expand_path(dirname))
+          expect(directory_exists?(dirname)).to be true
+        end
+      end
+    end
+
+    describe ".mkdir_p" do
+      subject(:mkdir_p) { DirectoryMaker.method(:mkdir_p) }
+      it_behaves_like "an mkdir_p implementation"
+    end
+
+    describe "FileUtils.mkdir_p" do
+      subject(:mkdir_p) { FileUtils.method(:mkdir_p) }
+      it_behaves_like "an mkdir_p implementation"
+    end
+  end
+end