Inline snapshots with line breaks are unstable

[AriPerkkio]

Describe the bug

Test below keeps failing when run. It passes right after the snapshot is updated but fails immediately on the next run. Snapshot update doesn't actually change any content. I think vitest doesn't handle line changes properly when comparing inline snapshots.

import { expect, test } from 'vitest';

/*
 * - npm run test
 * - Error -> Snapshot has changed. Press u
 * - Snapshot is updated, test passes. Press enter to re-run
 * - Error -> Snapshot has changed. Repeat previous steps...
 */

test('unstable snapshot', () => {
  expect(() => {
    throw new Error(['First line', 'Second line'].join('\n'));
  }).toThrowErrorMatchingInlineSnapshot(`
    "First line
    Second line"
  `);
});

vitest-unstable-snapshot.mp4

Reproduction

https://stackblitz.com/edit/vitest-dev-vitest-kxavky?file=test/basic.test.ts

System Info

Default Stackblitz environment.

Used Package Manager

npm

Validations

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• Read the Contributing Guidelines.
• Read the docs.
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• The provided reproduction is a minimal reproducible example of the bug.

[AriPerkkio]

vitest/packages/vitest/src/integrations/snapshot/port/state.ts

Lines 182 to 186 in 0c9137d

	match({
	testName,
	received,
	key,
	inlineSnapshot,

┌────────────────┬───────────────────────────────────────────┐
│ inlineSnapshot │ '\n    "First line\n    Second line"\n  ' │
│    received    │         'First line\nSecond line'         │
└────────────────┴───────────────────────────────────────────┘

vitest/packages/vitest/src/integrations/snapshot/port/state.ts

Line 205 in 0c9137d

const pass = expectedTrimmed === prepareExpected(receivedSerialized)

const pass
  = expectedTrimmed //                       "First line\n    Second line"
  === prepareExpected(receivedSerialized) // "First line\nSecond line"

Before comparing the receivedSerialized, all newlines inside the quotes should be indented with required amount of spaces, 4 in this case.

'First line\nSecond line'
to 
'First line\n    Second line'

This padding would ensure that intentional indention would work, e.g.

expect('Hello \n    world').toMatchInlineSnapshot...