servo/tests/wpt/web-platform-tests/console/console-label-conversion.any.js

"use strict";
// https://console.spec.whatwg/org/#counting
// https://console.spec.whatwg/org/#timing

const methods = ['count', 'countReset', 'time', 'timeLog', 'timeEnd'];

for (const method of methods) {
  test(() => {
    let labelToStringCalled = false;

    console[method]({
      toString() {
        labelToStringCalled = true;
      }
    });

    assert_true(labelToStringCalled, `${method}() must call toString() on label when label is an object`);
  }, `console.${method}()'s label gets converted to string via label.toString() when label is an object`);

  test(() => {
    assert_throws_js(Error, () => {
      console[method]({
        toString() {
          throw new Error('conversion error');
        }
      });
    }, `${method} must re-throw any exceptions thrown by label.toString() conversion`);
  }, `console.${method}() throws exceptions generated by erroneous label.toString() conversion`);
}