DOM Node Transformer

Write a function transformElement(element, newText, classToAdd, classToRemove) that takes a mock DOM element and updates its properties:

1. Sets element.textContent to newText.
2. Adds classToAdd using element.classList.add(...).
3. Removes classToRemove using element.classList.remove(...).
4. Returns the element.

Also write a helper function testDOM(textContent, classes, newText, classToAdd, classToRemove) that:

1. Creates a mock element:

const element = {
  textContent,
  classList: {
    classes: [...classes],
    add(c) { if (!this.classes.includes(c)) this.classes.push(c); },
    remove(c) { this.classes = this.classes.filter(x => x !== c); }
  }
};

1. Calls transformElement(...) and returns a plain object: { text: element.textContent, classes: element.classList.classes }.