Method match

packages/jest-snapshot/src/State.ts:197–314

({
    testName,
    received,
    key,
    inlineSnapshot,
    isInline,
    error,
    testFailing = false,
  }: SnapshotMatchOptions)

  }

  match({
    testName,
    received,
    key,
    inlineSnapshot,
    isInline,
    error,
    testFailing = false,
  }: SnapshotMatchOptions): SnapshotReturnOptions {
    this._counters.set(testName, (this._counters.get(testName) || 0) + 1);
    const count = Number(this._counters.get(testName));

    if (!key) {
      key = testNameToKey(testName, count);
    }

    // Do not mark the snapshot as "checked" if the snapshot is inline and
    // there's an external snapshot. This way the external snapshot can be
    // removed with `--updateSnapshot`.
    if (!(isInline && this._snapshotData[key] !== undefined)) {
      this._uncheckedKeys.delete(key);
    }

    const receivedSerialized = addExtraLineBreaks(
      serialize(received, undefined, this.snapshotFormat),
    );
    const expected = isInline ? inlineSnapshot : this._snapshotData[key];
    const pass = expected === receivedSerialized;
    const hasSnapshot = expected !== undefined;
    const snapshotIsPersisted = isInline || fs.existsSync(this._snapshotPath);

    if (pass && !isInline) {
      // Executing a snapshot file as JavaScript and writing the strings back
      // when other snapshots have changed loses the proper escaping for some
      // characters. Since we check every snapshot in every test, use the newly
      // generated formatted string.
      // Note that this is only relevant when a snapshot is added and the dirty
      // flag is set.
      this._snapshotData[key] = receivedSerialized;
    }

    // In pure matching only runs, return the match result while skipping any updates
    // reports.
    if (testFailing) {
      if (hasSnapshot && !isInline) {
        // Retain current snapshot values.
        this._addSnapshot(key, expected, {error, isInline});
      }
      return {
        actual: removeExtraLineBreaks(receivedSerialized),
        count,
        expected:
          expected === undefined ? undefined : removeExtraLineBreaks(expected),
        key,
        pass,
      };
    }