Function serialize

packages/test-utils/src/index.ts:196–199

(val)

expect.addSnapshotSerializer({
  serialize(val) {
    const bitmap = "bitmap" in val ? val.bitmap : val;
    return `Visualization:\n\n${testImgToStr(bitmap)}\n\nData:\n\n${testImageReadableMatrix(bitmap)}`;
  },
  test(val) {
    if ("bitmap" in val) {
      return true;