Python怎么去写单元测试用例去测试hello world呢

print('hello world')

import sys


def hi():
    print('hello world')

if __name__ == '__main__':
    old = sys.stdout

    with open('test','w') as oFile:
        sys.stdout = oFile
        hi()

    sys.stdout = old

    with open('test','r') as oFile:
        if 'hello world' + '\n' == oFile.readline():
            print('PASS')
        else:
            print('FAIL',file=sys.stderr)

C:\Users\suneee\AppData\Local\Programs\Python\Python36\python.exe E:/wangjz/PyWorkSpace/LearnPython/test.py
PASS

Process finished with exit code 0

def print(*args, sep=' ', end='\n', file=None): # known special case of print
    """
    print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
    
    Prints the values to a stream, or to sys.stdout by default.
    Optional keyword arguments:
    file:  a file-like object (stream); defaults to the current sys.stdout.
    sep:   string inserted between values, default a space.
    end:   string appended after the last value, default a newline.
    flush: whether to forcibly flush the stream.
    """
    pass