Function fnNameFor

packages/pretty-format/src/__tests__/AsymmetricMatcher.test.ts:14–21

(func: (...any: Array<any>) => unknown)

let options: OptionsReceived;

function fnNameFor(func: (...any: Array<any>) => unknown) {
  if (func.name) {
    return func.name;
  }

  const matches = func.toString().match(/^\s*function\s*(\w*)\s*\(/);
  return matches ? matches[1] : '<anonymous>';
}

beforeEach(() => {
  options = {plugins: [AsymmetricMatcher]};