Gulp-diff migrated to support Gulp 4.x task to diff files in the stream against a destination.
An example jsbeautify verification task to show diffs from js-beautify
'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 }));
});