chromium/src/third_party/blink/web_tests/inspector-protocol/runtime/runtime-console-log-node-custom.js

(async function testRemoteObjects(testRunner) {
  const {dp} = await testRunner.startBlank('Test description generation for custom elements.');
  dp.Runtime.enable();

  const result0 = await dp.Runtime.evaluate({ expression:
    `class WordCount extends HTMLParagraphElement {
      constructor() { super(); }
    };
    customElements.define('word-count', WordCount, { extends: 'p' });`
  });

  const result1 = await dp.Runtime.evaluate({ expression:
    `x = document.createElement("word-count"); x`
  });
  const result2 = await dp.Runtime.evaluate({ expression:
    `x.id = "x_id"; x`
  });
  const result3 = await dp.Runtime.evaluate({ expression:
    `x.className = "x_class"; x`
  });
  const result4 = await dp.Runtime.evaluate({ expression:
    `x.className = "x_class1 x_class2"; x`
  });

  testRunner.log(result1.result.result);
  testRunner.log(result2.result.result);
  testRunner.log(result3.result.result);
  testRunner.log(result4.result.result);
  testRunner.completeTest();
});