Add File.rename (a primitive of FileUtils.mv). Closes #29

lib/fakefs/file.rb

@@ -148,6 +148,23 @@ module FakeFS
       read(path).split("\n")
     end
 
+    def self.rename(source, dest)
+      if directory?(source) && file?(dest)
+        raise Errno::ENOTDIR, "Not a directory - #{source} or #{dest}"
+      elsif file?(source) && directory?(dest)
+        raise Errno::EISDIR, "Is a directory - #{source} or #{dest}"
+      end
+
+      if target = FileSystem.find(source)
+        FileSystem.add(dest, target.entry.clone)
+        FileSystem.delete(source)
+      else
+        raise Errno::ENOENT,  "No such file or directory - #{source} or #{dest}"
+      end
+
+      0
+    end
+
     def self.link(source, dest)
       if directory?(source)
         raise Errno::EPERM, "Operation not permitted - #{source} or #{dest}"

test/fakefs_test.rb

@@ -1267,6 +1267,61 @@ class FakeFSTest < Test::Unit::TestCase
     assert Dir.tmpdir == "/tmp"
   end
 
+  def test_rename_renames_a_file
+    FileUtils.touch("/foo")
+    File.rename("/foo", "/bar")
+    assert File.file?("/bar")
+  end
+
+  def test_rename_returns
+    FileUtils.touch("/foo")
+    assert_equal 0, File.rename("/foo", "/bar")
+  end
+
+  def test_rename_renames_two_files
+    FileUtils.touch("/foo")
+    FileUtils.touch("/bar")
+    File.rename("/foo", "/bar")
+    assert File.file?("/bar")
+
+  end
+
+  def test_rename_renames_a_directories
+    Dir.mkdir("/foo")
+    File.rename("/foo", "/bar")
+    assert File.directory?("/bar")
+  end
+
+  def test_rename_renames_two_directories
+    Dir.mkdir("/foo")
+    Dir.mkdir("/bar")
+    File.rename("/foo", "/bar")
+    assert File.directory?("/bar")
+  end
+
+  def test_rename_file_to_directory_raises_error
+    FileUtils.touch("/foo")
+    Dir.mkdir("/bar")
+    assert_raises(Errno::EISDIR) do
+      File.rename("/foo", "/bar")
+    end
+  end
+
+  def test_rename_directory_to_file_raises_error
+    Dir.mkdir("/foo")
+    FileUtils.touch("/bar")
+    assert_raises(Errno::ENOTDIR) do
+      File.rename("/foo", "/bar")
+    end
+  end
+
+
+  def test_rename_with_missing_source_raises_error
+    assert_raises(Errno::ENOENT) do
+      File.rename("/no_such_file", "/bar")
+    end
+  end
+
   def test_hard_link_creates_file
     FileUtils.touch("/foo")