Issue 87 - Added fs.fsync() as a no-op, and added tests. Modified documentation.

Made requested changes to tests, functionality; reverted doc changes

src/filesystem/implementation.js

@@ -1761,6 +1761,16 @@ function read(fs, context, fd, buffer, offset, length, position, callback) {
   }
 }
 
+function fsync(fs, context, fd, callback) {
+  if(validateInteger(fd, callback) !== fd) return;
+  var ofd = fs.openFiles[fd];
+  if(!ofd) {
+    callback(new Errors.EBADF());
+  } else {
+    callback();
+  }
+}
+
 function readFile(fs, context, path, options, callback) {
   callback = arguments[arguments.length - 1];
   options = validate_file_options(options, null, 'r');
@@ -2413,6 +2423,7 @@ module.exports = {
   stat: stat,
   fstat: fstat,
   link: link,
+  fsync: fsync,
   read: read,
   readFile: readFile,
   write: write,

src/filesystem/interface.js

@@ -282,6 +282,7 @@ function FileSystem(options, callback) {
     { name: 'rmdir', promises: true },
     { name: 'stat', promises: true },
     { name: 'fstat' },
+    { name: 'fsync' },
     { name: 'link', promises: true },
     { name: 'unlink', promises: true },
     { name: 'read' },

tests/index.js

@@ -24,6 +24,7 @@ require('./spec/fs.writeFile-readFile.spec');
 require('./spec/fs.appendFile.spec');
 require('./spec/fs.read.spec');
 require('./spec/fs.close.spec');
+require('./spec/fs.fsync.spec');
 require('./spec/fs.link.spec');
 require('./spec/fs.unlink.spec');
 require('./spec/fs.rename.spec');

tests/spec/fs.fsync.spec.js

@@ -0,0 +1,47 @@
+var util = require('../lib/test-utils.js');
+var expect = require('chai').expect;
+
+describe('fs.fsync', function() {
+  beforeEach(util.setup);
+  afterEach(util.cleanup);
+
+  it('should be a function', function() {
+    var fs = util.fs();
+    expect(fs.fsync).to.be.a('function');
+  });
+
+  it('should return error when fd is not a number', function(done) {
+    var fs = util.fs();
+    fs.fsync('1', function(error) {
+      expect(error).to.exist;
+      expect(error.code).to.equal('EINVAL');
+      done();
+    });
+  });
+
+  it('should return error when fd is invalid', function(done) {
+    var fs = util.fs();
+    fs.fsync(1, function(error) {
+      expect(error).to.exist;
+      expect(error.code).to.equal('EBADF');
+      done();
+    });
+  });
+
+  it('should not error if the fd is valid', function(done) {
+    var fs = util.fs();
+
+    fs.writeFile('/myfile', 'contents', function(error) {
+      if(error) throw error;
+
+      fs.open('/myfile', 'r', function(error, fd) {
+        if(error) throw error;
+
+        fs.fsync(fd, function(error) {
+          expect(error).to.not.exist;
+          fs.close(done);
+        });
+      });
+    });
+  });
+});