Issue 551-Add unwatchfile method

src/filesystem/interface.js

@@ -159,6 +159,23 @@ function FileSystem(options, callback) {
     return watcher;
   };
 
+  this.unwatchFile = function(filename, listener) {
+    if(isNullPath(filename)) {
+      throw new Error('Path must be a string without null bytes.');
+    }
+    listener = listener || nop;
+
+    var unwatcher = new FSWatcher();
+    unwatcher.start(filename, false, options.recursive);
+    if(listener != nop){
+      unwatcher.closeOneListener(filename);
+    }
+    else{
+      unwatcher.close();
+    }
+    return unwatcher;
+  };
+
   // Deal with various approaches to node ID creation
   function wrappedGuidFn(context) {
     return function(callback) {
@@ -347,7 +364,7 @@ function FileSystem(options, callback) {
         callback(error);
       }
     };
-    
+
     FileSystem.prototype.promises[methodName] = promisify(FileSystem.prototype[methodName].bind(fs));
   });
 

src/fs-watcher.js

@@ -1,7 +1,7 @@
 var EventEmitter = require('../lib/eventemitter.js');
 var Path = require('./path.js');
 var Intercom = require('../lib/intercom.js');
-
+var _watchers = {};
 /**
  * FSWatcher based on node.js' FSWatcher
  * see https://github.com/joyent/node/blob/master/lib/fs.js
@@ -45,11 +45,15 @@ function FSWatcher() {
     if(recursive) {
       recursivePathPrefix = filename === '/' ? '/' : filename + '/';
     }
-
+    _watchers[filename] = self;
     var intercom = Intercom.getInstance();
     intercom.on('change', onchange);
   };
 
+  self.closeOneListener = function(filename){
+    _watchers[filename].close();
+  };
+
   self.close = function() {
     var intercom = Intercom.getInstance();
     intercom.off('change', onchange);
@@ -58,5 +62,7 @@ function FSWatcher() {
 }
 FSWatcher.prototype = new EventEmitter();
 FSWatcher.prototype.constructor = FSWatcher;
-
+FSWatcher.getWatcherForFilename = function(filename) {
+  return _watchers[filename];
+};
 module.exports = FSWatcher;

tests/index.js

@@ -37,6 +37,7 @@ require('./spec/trailing-slashes.spec');
 require('./spec/times.spec');
 require('./spec/time-flags.spec');
 require('./spec/fs.watch.spec');
+require('./spec/fs.unwatchFile.spec');
 require('./spec/errors.spec');
 require('./spec/fs.shell.spec');
 require('./spec/fs.chmod.spec');

tests/spec/fs.unwatchFile.spec.js

@@ -0,0 +1,19 @@
+var util = require('../lib/test-utils.js');
+var expect = require('chai').expect;
+
+describe('fs.unwatchFile', function() {
+  beforeEach(util.setup);
+  afterEach(util.cleanup);
+
+  it('should be a function', function() {
+    var fs = util.fs();
+    expect(typeof fs.unwatchFile).to.equal('function');
+  });
+
+  it('should not throw an error when using a file not being watched', function() {
+    var fs = util.fs();
+    fs.unwatchFile('/myfile', function(error){
+      expect(error).not.to.exist;
+    });
+  });
+});