test for REPL .save and .load and documentation updates

doc/api/repl.markdown

@@ -79,6 +79,7 @@ connect to a long-running node process without restarting it.
 ### REPL Features
 
 Inside the REPL, Control+D will exit.  Multi-line expressions can be input.
+Tab completion is supported for both global and local variables.
 
 The special variable `_` (underscore) contains the result of the last expression.
 
@@ -113,6 +114,10 @@ There are a few special REPL commands:
     multi-line expression.
   - `.exit` - Close the I/O stream, which will cause the REPL to exit.
   - `.help` - Show this list of special commands.
+  - `.save` - Save the current REPL session to a file
+    >.save ./file/to/save.js
+  - `.load` - Load a file into the current REPL session.
+    >.load ./file/to/load.js
 
 The following key combinations in the REPL have these special effects:
 

test/simple/test-repl-.save.load.js

@@ -0,0 +1,101 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+var assert = require('assert');
+var util = require('util');
+var join = require('path').join;
+var fs = require('fs');
+var common = require('../common');
+
+var repl = require('repl');
+
+// A stream to push an array into a REPL
+function ArrayStream() {
+  this.run = function (data) {
+    var self = this;
+    data.forEach(function (line) {
+      self.emit('data', line);
+    });
+  }
+}
+util.inherits(ArrayStream, require('stream').Stream);
+ArrayStream.prototype.readable = true;
+ArrayStream.prototype.writable = true;
+ArrayStream.prototype.resume = function () {};
+ArrayStream.prototype.write = function () {};
+
+var works = [ [ 'inner.one' ], 'inner.o' ];
+
+var putIn = new ArrayStream();
+var testMe = repl.start('', putIn);
+
+
+var testFile = [
+  'var top = function () {',
+  'var inner = {one:1};'
+];
+var saveFileName = join(common.tmpDir, 'test.save.js');
+
+// input some data
+putIn.run(testFile);
+
+// save it to a file
+putIn.run(['.save ' + saveFileName]);
+
+// the file should have what I wrote
+assert.equal(
+  fs.readFileSync(saveFileName, 'utf8'),
+  testFile.join('\n') + '\n');
+
+// make sure that the REPL data is "correct"
+// so when I load it back I know I'm good
+testMe.complete('inner.o', function (error, data) {
+  assert.deepEqual(data, works);
+});
+
+// clear the REPL
+putIn.run(['.clear']);
+
+// Load the file back in
+putIn.run(['.load ' + saveFileName]);
+
+// make sure that the REPL data is "correct"
+testMe.complete('inner.o', function (error, data) {
+  assert.deepEqual(data, works);
+});
+
+// clear the REPL
+putIn.run(['.clear']);
+
+var loadFile = join(common.tmpDir, 'file.does.not.exist');
+
+// shold not break
+putIn.write = function(data) {
+  // make sure I get a failed to load message and not some crazy error
+  assert.equal(data,
+  'Failed to load:' + loadFile + '\n');
+  // eat me to avoid work
+  putIn.write = function() {};
+};
+putIn.run(['.load ' +loadFile]);
+
+
+//TODO how do I do a failed .save test?