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Jest Specific Snapshot

Jest matcher for multiple snapshot files per test

You can read about the implementation here

Installation

1npm i -D jest-specific-snapshot

Example

1const path = require('path');
2// extend jest to have 'toMatchSpecificSnapshot' matcher
3require('jest-specific-snapshot');
4
5test('test', () => {
6  // provides snapshot file with absolute file
7  const pathToSnap = path.resolve(process.cwd(), './example/specific/dir/my.shot');
8  expect(100).toMatchSpecificSnapshot(pathToSnap);
9
10  //same snapshot but with relative file
11  expect(14).toMatchSpecificSnapshot('./specific/dir/my.shot');
12
13  // another snapshot file in the same test
14  expect(19).toMatchSpecificSnapshot('./specific/another_dir/another.shot');
15});

With Custom Serializer

1// extend jest to have 'toMatchSpecificSnapshot' matcher
2const addSerializer = require('jest-specific-snapshot').addSerializer;
3
4addSerializer(/* Add custom serializer here */);
5
6test('test', () => {
7  expect(/* thing that matches the custom serializer */).toMatchSpecificSnapshot(
8    './specific/custom_serializer/test.shot'
9  );
10});

Extend toMatchSpecificSnapshot

1const toMatchSpecificSnapshot = require('jest-specific-snapshot').toMatchSpecificSnapshot;
2
3expect.extend({
4  toMatchDecoratedSpecificSnapshot(received, snapshotFile) {
5    // You can modify received data or create dynamic snapshot path
6    const data = doSomeThing(received);
7    return toMatchSpecificSnapshot.call(this, data, snapshotFile);
8  },
9});

Limitations

1. Snapshot files should have an extension other than .snap, since it conflicts with jest.
2. In order to handle the --updateSnapshot (-u) parameter provided from CLI, there is an abuse of the SnapshotState._updateSnapshot private field. TBD - try to use the globalConfig to get this state.
3. .toMatchSpecificSnapshot does ignore a custom serializers strategy. In order to support custom serializers, you should use the addSerializer method explicitly.