toMatchSnapshot.js

import { SnapshotState, toMatchSnapshot } from ‘jest-snapshot’;

export function toMatchSnapshot(actual, testFile, testTitle) {
 // Intilize the SnapshotState, it’s responsible for actually matching
 // actual snapshot with expected one and storing results to `__snapshots__` folder
 const snapshotState = new SnapshotState(testFile, {
  updateSnapshot: process.env.SNAPSHOT_UPDATE ? ‘all’ : ‘new’,
 });
 
 // Bind the `toMatchSnapshot` to the object with snapshotState and
 // currentTest name, as `toMatchSnapshot` expects it as it’s `this`
 // object members
 const matcher = toMatchSnapshot.bind({
  snapshotState,
  currentTestName: testTitle,
 });
  
 // Execute the matcher
 const result = matcher(actual);
 
 // Store the state of snapshot, depending on updateSnapshot value
 snapshotState.save();
  
 // Return results outside
 return result;
}