* lisp/eshell/esh-io.el (eshell-pipe-broken): New error.
(eshell-output-object-to-target): Signal 'eshell-pipe-broken' if the
target is an exited/signaled process.
* lisp/eshell/esh-proc.el (eshell-insertion-filter): Handle
'eshell-pipe-broken'.
* test/lisp/eshell/esh-proc-tests.el: New test.
* test/lisp/eshell/eshell-tests.el
* test/lisp/eshell/em-extpipe-tests.el: Load eshell-tests-helpers with
'require'.
* test/lisp/eshell/eshell-tests-helpers.el (eshell-history-file-name):
Define this here so individual test files don't have to.
Previously, input was sent to the last process in the pipeline,
resulting in unexpected behavior when running commands like
'tr a-z A-Z | rev'.
* lisp/eshell/esh-util.el (eshell-process-pair-p)
(eshell-make-process-pair): New functions.
* lisp/eshell/esh-cmd.el (eshell-last-async-proc): Rename to...
(eshell-last-async-procs): ... this, and store a pair of processes.
(eshell-interactive-process): Replace with...
(eshell-interactive-process-p, eshell-head-process)
(eshell-tail-process): ... these.
(eshell-cmd-initialize): Set 'eshell-last-async-procs'.
(eshell-do-pipelines): Set 'headproc'.
(eshell-execute-pipeline): Return 'headproc' and 'tailproc'.
(eshell-resume-eval): Use 'eshell-last-async-procs'.
(eshell-do-eval): Make sure we work with a pair of processes.
* lisp/eshell/esh-proc.el (eshell-send-eof-to-process): Move from
here...
* lisp/eshell/esh-mode.el (eshell-send-eof-to-process): ... to here,
and only send EOF to the head process.
* lisp/eshell/em-cmpl.el (eshell-complete-parse-arguments)
* lisp/eshell/esh-mode.el (eshell-intercept-commands)
(eshell-watch-for-password-prompt):
Use 'eshell-interactive-process-p'.
* lisp/eshell/em-rebind.el (eshell-delchar-or-maybe-eof)
* lisp/eshell/em-term.el (eshell-term-send-raw-string)
* lisp/eshell/esh-mode.el (eshell-self-insert-command)
(eshell-send-input, eshell-send-invisible):
Use 'eshell-head-process'.
* lisp/eshell/esh-cmd.el (eshell-as-subcommand):
Use 'eshell-tail-process'.
* lisp/eshell/eshell.el (eshell-command):
* test/lisp/eshell/eshell-tests-helpers.el
(eshell-wait-for-subprocess):
Use 'eshell-interactive-process-p' and 'eshell-tail-process'.
* test/lisp/eshell/eshell-tests.el (eshell-test/pipe-headproc-stdin):
New test.
When using eshell-match-result via eshell-command-result-p to examine
the output of asynchronous Eshell commands, a newly emitted prompt is
included in the text against which the regexp is matched. This makes
it awkward to match against the whole output; for example, to check
whether it is empty. Rework the function to exclude the prompt.
* test/lisp/eshell/eshell-tests-helpers.el (eshell-match-result):
Exclude any newly emitted prompt from the text against which the
regexp is matched. Additionally, the function no longer moves point.
* test/lisp/eshell/eshell-tests.el (eshell-test/flush-output): Update
and simplify test given how eshell-match-result no longer moves point.
