test(shell-test): call tcdrain() on stdout and stderr on exit (#38177)

Similar to #38154, shell-test also has the same problem on FreeBSD:

FAILED
1 test, listed below:
FAILED
test/functional/terminal/ex_terminal_spec.lua @
237:
:terminal (with fake shell) executes a given command through the shell
test/functional/terminal/ex_terminal_spec.lua:239: Row 1 did not match.
Expected:
  |*^ready $ echo hi                                   |
  |*                                                  |
  |*[Process exited 0]                                |
  |                                                  |
Actual:
  |*^                                                  |
  |*[Process exited 0]                                |
  |*                                                  |
  |                                                  |
To print the expect() call that would assert the current screen state, use
screen:snapshot_util(). In case of non-deterministic failures, use
screen:redraw_debug() to show all intermediate screen states.
Snapshot:
screen:expect([[
  ^                                                  |
  [Process exited 0]                                |
                                                    |*2
]])
stack traceback:
	test/functional/ui/screen.lua:909: in function '_wait'
	test/functional/ui/screen.lua:537: in function 'expect'
	test/functional/terminal/ex_terminal_spec.lua:239: in function <test/functional/terminal/ex_terminal_spec.lua:237>

Running the test repeatedly somehow doesn't trigger the problem, but as
mentioned in #36792 a similar problem has also happened previously.

0 files changed, 0 insertions, 0 deletions