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

[mscheifer]

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

[StanFromIreland]

IMO there should be no output, the output should still be buffered.

That is what currently happens:

/tmp$ python3.15 -m unittest -b test.py
E
Stdout:
hello
> /tmp/test.py(6)test()
-> breakpoint()
(Pdb) 
Quitting pdb will kill the process. Quit anyway? [y/n] 

======================================================================
ERROR: test (test.Test.test)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/test.py", line 6, in test
    breakpoint()
    ~~~~~~~~~~^^
  File "/usr/local/lib/python3.15/bdb.py", line 94, in wrapper
    ret = func(frame, *args)
  File "/usr/local/lib/python3.15/bdb.py", line 154, in opcode_callback
    frame.f_trace(frame, 'opcode', None)
    ~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.15/bdb.py", line 298, in trace_dispatch
    return self.dispatch_opcode(frame, arg)
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/usr/local/lib/python3.15/bdb.py", line 415, in dispatch_opcode
    self.user_opcode(frame)
    ~~~~~~~~~~~~~~~~^^^^^^^
  File "/usr/local/lib/python3.15/pdb.py", line 546, in user_line
    self.interaction(frame, None)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  File "/usr/local/lib/python3.15/pdb.py", line 735, in interaction
    self._cmdloop()
    ~~~~~~~~~~~~~^^
  File "/usr/local/lib/python3.15/pdb.py", line 600, in _cmdloop
    self.cmdloop()
    ~~~~~~~~~~~~^^
  File "/usr/local/lib/python3.15/cmd.py", line 149, in cmdloop
    stop = self.onecmd(line)
  File "/usr/local/lib/python3.15/pdb.py", line 1037, in onecmd
    return cmd.Cmd.onecmd(self, line)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^
  File "/usr/local/lib/python3.15/cmd.py", line 227, in onecmd
    return func(arg)
  File "/usr/local/lib/python3.15/pdb.py", line 1998, in do_EOF
    return self.do_quit(arg)
           ~~~~~~~~~~~~^^^^^
  File "/usr/local/lib/python3.15/pdb.py", line 1981, in do_quit
    sys.exit(1)
    ~~~~~~~~^^^
SystemExit: 1

Stdout:
hello
> /tmp/test.py(6)test()
-> breakpoint()
(Pdb) 
Quitting pdb will kill the process. Quit anyway? [y/n] 

----------------------------------------------------------------------
Ran 1 test in 2.585s

FAILED (errors=1)

This should be closed, there is no bug, it works logically.

[mscheifer]

That is what currently happens:

Are you pressing Ctrl-D before it prints anything?

I don't think it's obvious that the debugger CLI should be considered part of the output of the test.