python代码playwright库 expect_file_chooser()

`expect_file_chooser()`是Playwright库中的一个函数，用于模拟文件选择器的操作。它可以等待文件选择器弹出，并模拟用户选择文件的操作。

以下是使用`expect_file_chooser()`函数的示例代码：

import asyncio
from playwright.async_api import Playwright, async_playwright

async def file_chooser_example(playwright: Playwright) -> None:
    # Launch the browser
    browser = await playwright.chromium.launch()
    page = await browser.new_page()

    # Navigate to a page with a file input element
    await page.goto("https://www.example.com")

    # Define a coroutine to handle the file chooser dialog
    async def handle_file_chooser(dialog):
        await dialog.set_files("./example.txt")
        await dialog.accept()

    # Listen for the file chooser dialog and handle it
    page.on("filechooser", handle_file_chooser)

    # Click the file input element to trigger the file chooser dialog
    await page.click("#file-input")

    # Wait for the file to be selected and uploaded
    await page.wait_for_selector("#file-uploaded")

    # Close the browser
    await browser.close()

# Run the example
with async_playwright() as playwright:
    asyncio.run(file_chooser_example(playwright))

该示例使用Playwright库启动一个Chromium浏览器实例，并在页面上找到一个文件输入元素。当用户单击该元素时，将弹出文件选择器对话框。`expect_file_chooser()`函数会等待该对话框出现并模拟用户选择文件的操作。然后，该示例会等待文件上传完成并关闭浏览器。