Web Components Conformance Tests

custom-element-conformance.js

const NativeHTMLElement = window.HTMLElement;
const documentWrite = document.write;
const documentOpen = document.open;


window.HTMLElement = class extends NativeHTMLElement {
  constructor(...args) {
    console.assert(args.length === 0);
    super();
  }
}

export const createConformanceWrapper = (testSubject) =>
  class extends testSubject {
    constructor(...args) {
      document.write = function() { throw new Error(); };
      document.open = function() { throw new Error(); };
      this.getAttribute = function () { throw new Error(); };
      Object.defineProperty(this, 'attributes', {
        get() { throw new Error(); }
      });
      // Guards for children, childNodes, firstChild, etc.
      // Guard for innerHTML?

      super(args);

      // It's possible these tests should go in the microtask queue
      console.assert(this instanceof testSubject, 'Element has wrong prototype');
      console.assert(this.hasAttributes() === false, 'Element has attributes');
      console.assert(this.hasChildNodes() === false, 'Element has children');
      document.write = documentWrite;
      document.open = documentOpen;
      delete this.getAttribute;
      delete this.attributes, 
      // Remove other guards
    }
  };

export const runTests(testSubject) {
  const wrapper = createConformanceWrapper(testSubject);
  // Create iframe to test parser creation
  // Create with innerHTML
  // Create with createElement();
  // Adopt into another document
  // append, remove, append to test multiple connectedCallbacks
}