Adding the basics for Pathname support (ref #13)

lib/memfs.rb

@@ -22,10 +22,16 @@ module MemFs
   # Keeps track of the original Ruby File class.
   OriginalFile = ::File
 
+  if defined?(::Pathname)
+    # Keeps track of the original Ruby Pathname class.
+    OriginalPathname = ::Pathname
+  end
+
   require 'memfs/file_system'
   require 'memfs/dir'
   require 'memfs/file'
   require 'memfs/file/stat'
+  require 'memfs/pathname'
 
   # Calls the given block with MemFs activated.
   #
@@ -77,6 +83,11 @@ def activate!
 
       const_set :Dir, MemFs::Dir
       const_set :File, MemFs::File
+
+      if defined?(::Pathname)
+        remove_const :Pathname
+        const_set :Pathname, MemFs::Pathname
+      end
     end
 
     MemFs::FileSystem.instance.clear!
@@ -96,6 +107,11 @@ def deactivate!
 
       const_set :Dir, MemFs::OriginalDir
       const_set :File, MemFs::OriginalFile
+
+      if defined?(::Pathname)
+        remove_const :Pathname
+        const_set :Pathname, MemFs::OriginalPathname
+      end
     end
   end
   module_function :deactivate!

lib/memfs/pathname.rb

@@ -0,0 +1,20 @@
+require 'memfs/filesystem_access'
+
+module MemFs
+  class Pathname
+    extend FilesystemAccess
+
+    def initialize(path)
+      @path = '' + path
+    end
+
+    def to_s
+      path
+    end
+    alias_method :to_str, :to_s
+
+    private
+
+    attr_reader :path
+  end
+end

spec/memfs/file_spec.rb

@@ -944,6 +944,12 @@ module MemFs
           expect(path).to eq '/some/path'
         end
       end
+
+      context 'when the path cannot be converted to a string' do
+        it 'raises an exception' do
+          expect { subject.path(42) }.to raise_error(ArgumentError)
+        end
+      end
     end
 
     describe '.pipe?' do

spec/memfs/pathname_spec.rb

@@ -0,0 +1,40 @@
+require 'spec_helper'
+
+module MemFs
+  describe Pathname do
+    describe 'Class Methods' do
+      subject { MemFs::Pathname }
+
+      describe '.new' do
+        it 'creates a Pathname object from the given path' do
+          pathname = subject.new('some/path')
+          expect(pathname.to_s).to eq 'some/path'
+        end
+
+        context 'when the given path is not a string' do
+          it 'creates a Pathname object from the string representation of the path' do
+            path = MemFs::Pathname.new('some/path')
+            pathname = MemFs::Pathname.new(path)
+            expect(pathname.to_s).to eq 'some/path'
+          end
+        end
+      end
+    end
+
+    describe "Instance Methods" do
+      subject(:pathname) { MemFs::Pathname.new('some/path') }
+
+      describe '#to_str' do
+        it 'can be converted to a string object' do
+          expect('test ' + pathname).to eq 'test some/path'
+        end
+      end
+
+      describe '#to_s' do
+        it "returns the path as a String" do
+          expect(pathname.to_s).to eq 'some/path'
+        end
+      end
+    end
+  end
+end

spec/memfs_spec.rb

@@ -23,31 +23,67 @@
   end
 
   describe '.activate!' do
-    before(:each) { described_class.activate! }
-    after(:each)  { described_class.deactivate! }
-
     it 'replaces Ruby Dir class with a fake one' do
+      subject.activate!
       expect(::Dir).to be(described_class::Dir)
+      subject.deactivate!
     end
 
     it 'replaces Ruby File class with a fake one' do
+      subject.activate!
       expect(::File).to be(described_class::File)
+      subject.deactivate!
     end
-  end
 
-  describe '.deactivate!' do
-    before :each do
-      described_class.activate!
-      described_class.deactivate!
+    context 'when Pathname is defined' do
+      it 'replaces Ruby Pathname class with a fake one' do
+        class ::Pathname; end
+        subject.activate!
+        expect(::Pathname).to be(described_class::Pathname)
+        subject.deactivate!
+        Object.send(:remove_const, :Pathname)
+      end
     end
 
+    context 'when Pathname is not defined' do
+      it 'does not replace Ruby Pathname class with a fake one' do
+        subject.activate!
+        expect { Object.const_get(:Pathname) }.to raise_error(NameError)
+        subject.deactivate!
+      end
+    end
+  end
+
+  describe '.deactivate!' do
     it 'sets back the Ruby Dir class to the original one' do
+      subject.activate!
+      subject.deactivate!
       expect(::Dir).to be(described_class::OriginalDir)
     end
 
     it 'sets back the Ruby File class to the original one' do
+      subject.activate!
+      subject.deactivate!
       expect(::File).to be(described_class::OriginalFile)
     end
+
+    context 'when Pathname is defined' do
+      it 'sets back the Ruby Pathname class to the original one' do
+        class ::Pathname; end
+        subject.activate!
+        subject.deactivate!
+        expect(::Pathname).to be(described_class::OriginalPathname)
+        Object.send(:remove_const, :Pathname)
+      end
+    end
+
+    context 'when Pathname is not defined' do
+      it 'does not set the Pathname constant' do
+        subject.activate!
+        subject.deactivate!
+        expect { Object.const_get(:Pathname) }.to raise_error(NameError)
+      end
+    end
   end
 
   describe '.touch' do