snap-shot-compare

Picks best comparison / diff for snapshot value

Why

Use this comparator function with snap-shot-core

Install

Requires Node version 6 or above.

npm install --save snap-shot-compare

Use

Compare returns a Folktale.Result object.

const compare = require('snap-shot-compare')
let result
// if values are equal
compare({
  expected: 42,
  value: 100
}).map(console.log)
// prints undefined
 
// if objects are different
compare({
  expected: {foo: 'foo'},
  value: {bar: 'bar'}
}).orElse(console.log)
// result has ANSI characters
// use "strip-ansi" to remove if desired
/*
snapshot difference
{
- foo: "foo"
+ bar: "bar"
}
*/

When showing the diff, - is for the lines removed, + means a line has been added.

Other options

There are a few secondary options that might not be consistent across all comparison modes (open a GitHub issue if an unexpected behavior is found)

compare({
  expected,
  value,
  noColor,  // strips ASCII color from diff message
  json      // returns error result as JSON object
            // with the following properties
            // {message, expected, value}
})

Note: json = true option means noColor = true automatically.

Uses

• Folktale.Result
• variable-diff to show diff between two objects
• disparity to show diff between multi line text

For longer text fragments, prints "expected" and "actual" values when showing the difference.

Debug

To see verbose logs run with environment variable

DEBUG=snap-shot-compare

Small print

Author: Gleb Bahmutov <[e-mail]> © 2017

• @bahmutov
• glebbahmutov.com
• blog

License: MIT - do anything with the code, but don't blame me if it does not work.

Support: if you find any problems with this module, email / tweet / open issue on Github

MIT License

Copyright (c) 2017 Gleb Bahmutov <[e-mail]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.