Snapshot feature shows empty diff when changing order of keys on object

[raymond-h]

Description

When using the snapshot feature, if the new value is an object that is identical to the snapshot but with a different key order, the diff shown is empty.

Test Source

Before:

	...
	t.snapshot({
		coolNumber: 5 + 8,
		otherNumber: 9 + 8,
	});
	...

After altering the test so that the keys are in reversed order:

	...
	t.snapshot({
		otherNumber: 9 + 8,
		coolNumber: 5 + 8,
	});
	...

Error Message & Stack Trace

  1 failed

  banana
  test/test.js:6

   5: test('banana', async t => {
   6:   t.snapshot({             
   7:     otherNumber: 9 + 8,    

  Difference:

 
  Please check your code or --update-snapshots

  Test.<anonymous> (test/test.js:6:4)
  Test.fn (test/test.js:5:1)

Config

package.json:

{
  "ava": {
    "require": [
      "babel-register"
    ],
    "babel": "inherit"
  }
}

.babelrc:

{
    "plugins": [
        "transform-runtime"
    ],
    "presets": [
        "stage-0",
        "es2015-node4"
    ]
}

Command-Line Arguments

ava

Environment

Node.js v4.6.2
linux 4.8.0-34-generic

AVA 0.18.0

npm 3.10.9

[novemberborn]

@vadimdemedes I assume magic assert doesn't care about key order? I suppose the snapshot comparison does, which seems fair.

[novemberborn]

Please see #1275 for context.

[vadimdemedes]

@vadimdemedes I assume magic assert doesn't care about key order? I suppose the snapshot comparison does, which seems fair.

Nope, it doesn't. t.deepEqual() doesn't care about key order, so you won't simply get an error, so it won't even "get to" magic-assert.

[novemberborn]

The issue is that we're actually comparing JSON strings inside jest-snapshot, so key order suddenly matters. That's not how jest-snapshot behaves otherwise (I think because pretty-format sorts the keys).