gulp-diff 

Gulp task to diff files in the stream against a destination.

Usage

An example jsbeautify verification task to show diffs from js-beautify

``javascript
'use strict';

var gulp = require('gulp');
var prettify = require('gulp-jsbeautifier');
var diff = require('gulp-diff');

gulp.task('js-beautify', function() {
return gulp.src([
'!node_modules/*/.js',
'*/.js'
])
.pipe(prettify({
config: '.jsbeautifyrc',
mode: 'VERIFY_AND_WRITE'
}))
.pipe(diff(/ 'target directory to diff against', defaults to diff against original source file /))
// emit an error on finding diffs
.pipe(diff.reporter({ fail: true }));
});
``