previousElement
選択されたDOM要素の前の兄弟要素を返します。
使い方
$(selector).previousElement()
例
index.html
<div class="parent">
    <p>Sibling One</p>
    <p>Sibling Two</p>
    <p>Sibling Three</p>
</div>
previousElement.js
it('should get text from previous sibling element', async () => {
    const elem = await $$('p');
    const previousElem = await elem[1].previousElement()
    console.log(await previousElem.getText()); // outputs: "Sibling One"
});