tests/test-logtoprocess.t

pager: exit cleanly on SIGPIPE (BC)

Changeset aaa751585325 removes SIGPIPE handling completely. This is wrong,
as it means that Mercurial does not exit when the pager does. Instead, raise
SignalInterrupt when SIGPIPE happens with a pager attached, to trigger the
normal exit path.

This will cause "killed!" to be printed to stderr (hence the BC warning),
but in the normal pager use case (where the pager gets both stderr and
stdout), this message is lost as we only get SIGPIPE when the pager quits.

Test if logtoprocess correctly captures command-related log calls.

  $ hg init
  $ cat > $TESTTMP/foocommand.py << EOF
  > from mercurial import cmdutil
  > from time import sleep
  > cmdtable = {}
  > command = cmdutil.command(cmdtable)
  > @command('foo', [])
  > def foo(ui, repo):
  >     ui.log('foo', 'a message: %(bar)s\n', bar='spam')
  > EOF
  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > logtoprocess=
  > foocommand=$TESTTMP/foocommand.py
  > [logtoprocess]
  > command=echo 'logtoprocess command output:';
  >     echo "\$EVENT";
  >     echo "\$MSG1";
  >     echo "\$MSG2"
  > commandfinish=echo 'logtoprocess commandfinish output:';
  >     echo "\$EVENT";
  >     echo "\$MSG1";
  >     echo "\$MSG2";
  >     echo "\$MSG3"
  > foo=echo 'logtoprocess foo output:';
  >     echo "\$EVENT";
  >     echo "\$MSG1";
  >     echo "\$OPT_BAR"
  > EOF

Running a command triggers both a ui.log('command') and a
ui.log('commandfinish') call. The foo command also uses ui.log.

Use head to ensure we wait for all lines to be produced, and sort to avoid
ordering issues between the various processes we spawn:
  $ hg foo | head -n 17 | sort
  
  
  
  0
  a message: spam
  command
  commandfinish
  foo
  foo
  foo
  foo
  foo exited 0 after * seconds (glob)
  logtoprocess command output:
  logtoprocess commandfinish output:
  logtoprocess foo output:
  spam