I face this error when was running the test.py.
After some troubleshooting i found the function (generate_featured_image) is expecting two parameters
def generate_featured_image(text, meta_title):
But only one is sent
featured_image = generate_featured_image( meta_title)
I make it work replacing the text with url_slug and adding that parameter to the calling function
def generate_featured_image(url_slug, meta_title):
featured_image = generate_featured_image(url_slug, meta_title)
If you wanted i can do a PR to fix this issue.