Add method readAsStream on fs model

lib/fs/node.js

@@ -36,6 +36,7 @@ module.exports = function createNodeFS(root) {
         fsReadFile: fs.readFile,
         fsStatFile: fs.stat,
         fsReadDir: fsReadDir,
-        fsLoadObject: fsLoadObject
+        fsLoadObject: fsLoadObject,
+        fsReadAsStream: fs.readStream
     });
 };

lib/models/fs.js

@@ -1,5 +1,6 @@
 var path = require('path');
 var Immutable = require('immutable');
+var stream = require('stream');
 
 var File = require('./file');
 var Promise = require('../utils/promise');
@@ -13,7 +14,9 @@ var FS = Immutable.Record({
     fsReadFile:       Function(),
     fsStatFile:       Function(),
     fsReadDir:        Function(),
-    fsLoadObject:     null
+
+    fsLoadObject:     null,
+    fsReadAsStream:   null
 });
 
 /**
@@ -111,6 +114,30 @@ FS.prototype.readAsString = function(filename, encoding) {
     });
 };
 
+/**
+    Read file as a stream
+
+    @param {String} filename
+    @return {Promise<Stream>}
+*/
+FS.prototype.readAsStream = function(filename) {
+    var that = this;
+    var filepath = that.resolve(filename);
+    var fsReadAsStream = this.get('fsReadAsStream');
+
+    if (fsReadAsStream) {
+        return Promise(fsReadAsStream(filepath));
+    }
+
+    return this.read(filename)
+    .then(function(buf) {
+        var bufferStream = new stream.PassThrough();
+        bufferStream.end(buf);
+
+        return bufferStream;
+    });
+};
+
 /**
     Read stat infos about a file
 

lib/utils/fs.js

@@ -157,6 +157,7 @@ module.exports = {
     statSync: fs.statSync,
     readdir: Promise.nfbind(fs.readdir),
     writeStream: writeStream,
+    readStream: fs.createReadStream,
     copy: Promise.nfbind(cp),
     copyDir: Promise.nfbind(cpr),
     tmpFile: genTmpFile,