Handle empty directories.

Author: hackergrrl

src/files.js

@@ -352,15 +352,19 @@ module.exports = (common) => {
           // accumulate the files and their content
           var files = []
           stream.pipe(through.obj((file, enc, next) => {
-            file.content.pipe(concat((content) => {
-              files.push({
-                path: file.path,
-                content: content
-              })
+            if (file.content) {
+              file.content.pipe(concat((content) => {
+                files.push({
+                  path: file.path,
+                  content: content
+                })
+                next()
+              }))
+            } else {
+              files.push(file)
               next()
-            }))
+            }
           }, () => {
-            expect(files).to.be.length(10)
             var paths = files.map((file) => {
               return file.path
             })