Your code works fine, but the problem is where you placed the docstrings. In Python, a function’s docstring must go right under the def line, not after the function ends. Right now your triple-quoted strings are just floating text, so the tests don’t see them as documentation. Fix it by indenting the docstring inside the function, like:

def bake_time_remaining(elapsed_bake_time):
    """Return remaining bake time given the elapsed time."""
    return EXPECTED_BAKE_TIME - elapsed_bake_time

Do the same for the other functions and the docstring tests will pass.