The `unittest` `-b` command line option hides the output of `pdb`.

Bug report

Bug description:

import unittest

class Test(unittest.TestCase):
    def test(self):
        print("hello")
        breakpoint()
        print("goodbye")

If I invoke this like:

$ python3 -m unittest -b repo.py

Nothing is printed and the process sits waiting on input.

Whereas without the -b option we get the Pdb prompt:

$ python3 -m unittest repo.py 
hello
> /home/matthew/code/coveragepy_issue_1963/repo.py(7)test()
-> print("goodbye")
(Pdb) 

I would expect that the debugger prompt would not be swallowed up by the "-b" option, or that some error message would pop up saying that the "-b" option and the debugger were incompatible.

CPython versions tested on:

3.12

Operating systems tested on:

Linux

首先运行报告中的复现命令 python3 -m unittest -b repo.py，并将其与不使用缓冲的命令进行比较。跟踪 unittest 的 -b 输出缓冲如何与 breakpoint() 和 pdb 交互，然后为这种交互添加覆盖；当调试器提示符可用，或产生明确的不兼容错误时，即表示完成。