Add rewind method to file operations.

Author: joshuamcginnis

lib/net/sftp/operations/file.rb

@@ -131,11 +131,14 @@ def print(*items)
       nil
     end
 
-    # Returns the size of the file from stats
     def size
       stat.size
     end
 
+    def rewind
+      self.pos = 0
+    end
+
     # Writes each argument to the stream, appending a newline to any item
     # that does not already end in a newline. Array arguments are flattened.
     def puts(*items)

test/test_file.rb

@@ -162,4 +162,14 @@ def test_size_should_return_size_from_stat
     @sftp.expects(:fstat!).with("handle").returns(stat)
     assert_equal 1024, @file.size
   end
+
+  def test_rewind
+    @sftp.expects(:write!).with("handle", 0, "hello world\n")
+    @sftp.expects(:read!).with("handle", 12, 8192).returns("hello world\n")
+    @sftp.expects(:read!).with("handle", 0, 8192).returns("hello world\n")
+    @file.puts "hello world\n"
+    assert_equal "hello", @file.read(5)
+    @file.rewind
+    assert_equal "hello world", @file.read(11)
+  end
 end