Subject: 30.0.50; [PATCH] Add regression tests for synchronous processes in Eshell

From: Jim Porter <[email-masked]>
Date: Fri, 31 Mar 2023 21:41:09 -0700

As far as I understand it, Eshell only uses synchronous processes on 
MS-DOS (where 'make-process' doesn't exist). Since I don't build Emacs 
for MS-DOS, and I expect not many others do either, I'm worried that 
this support will regress. To avoid that, here are some regression tests.

It also fixes a small bug with how Eshell updated its internal markers 
when using synchronous processes. This mostly affects the tests, but 
could also cause unexpected behavior when using some of Eshell's 
buffer-navigation commands.

From f6a0f2d74fcac44a4faeb3c0b73184d5498ec525 Mon Sep 17 00:00:00 2001
From: Jim Porter <[email-masked]>
Date: Fri, 31 Mar 2023 21:32:44 -0700
Subject: [PATCH] ; Add tests for synchronous processes in Eshell

Normally, Eshell only uses synchronous processes on MS-DOS, so this is
hard to test.  To get around this, let the tests explicitly request
synchronous processes.

* lisp/eshell/esh-proc.el (eshell-supports-asynchronous-processes):
New variable...
(eshell-gather-process-output): ... use it, and remove some incorrect
code updating Eshell's internal markers (the async code path doesn't
do this, so neither should the sync path).

* lisp/eshell/esh-cmd.el (eshell-execute-pipeline): Use
'eshell-supports-asynchronous-processes'.

* test/lisp/eshell/esh-proc-tests.el
(esh-proc-test/synchronous-proc/simple/interactive)
(esh-proc-test/synchronous-proc/simple/command-result)
(esh-proc-test/synchronous-proc/pipeline/interactive)
(esh-proc-test/synchronous-proc/pipeline/command-result): New tests.
---
 lisp/eshell/esh-cmd.el             |  2 +-
 lisp/eshell/esh-proc.el            |  9 ++++----
 test/lisp/eshell/esh-proc-tests.el | 35 ++++++++++++++++++++++++++++++
 3 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/lisp/eshell/esh-cmd.el b/lisp/eshell/esh-cmd.el
index d5237ee1f04..b80596f2cad 100644
--- a/lisp/eshell/esh-cmd.el
+++ b/lisp/eshell/esh-cmd.el
@@ -892,7 +892,7 @@ eshell-execute-pipeline
      (set headproc nil)
      (set tailproc nil)
      (progn
-       ,(if (fboundp 'make-process)
+       ,(if eshell-supports-asynchronous-processes
 	    `(eshell-do-pipelines ,pipeline)
           `(let ((tail-handles (eshell-duplicate-handles
                                 eshell-current-handles)))
diff --git a/lisp/eshell/esh-proc.el b/lisp/eshell/esh-proc.el
index a86e7502795..2976f5694d7 100644
--- a/lisp/eshell/esh-proc.el
+++ b/lisp/eshell/esh-proc.el
@@ -97,6 +97,9 @@ eshell-kill-hook
 
 ;;; Internal Variables:
 
+(defvar eshell-supports-asynchronous-processes (fboundp 'make-process)
+  "Non-nil if Eshell can create asynchronous processes.")
+
 (defvar eshell-current-subjob-p nil)
 
 (defvar eshell-process-list nil
@@ -296,7 +299,7 @@ eshell-gather-process-output
                 (coding-system-change-eol-conversion locale-coding-system
                                                      'unix))))
     (cond
-     ((fboundp 'make-process)
+     (eshell-supports-asynchronous-processes
       (unless (or ;; FIXME: It's not currently possible to use a
                   ;; stderr process for remote files.
                   (file-remote-p default-directory)
@@ -392,10 +395,6 @@ eshell-gather-process-output
 	    (setq lbeg lend)
 	    (set-buffer proc-buf))
 	  (set-buffer oldbuf))
-        (require 'esh-mode)
-        (declare-function eshell-update-markers "esh-mode" (pmark))
-        (defvar eshell-last-output-end)         ;Defined in esh-mode.el.
-	(eshell-update-markers eshell-last-output-end)
 	;; Simulate the effect of eshell-sentinel.
 	(eshell-close-handles
          (if (numberp exit-status) exit-status -1)
diff --git a/test/lisp/eshell/esh-proc-tests.el b/test/lisp/eshell/esh-proc-tests.el
index 8e02fbb5497..8399fbdeeb9 100644
--- a/test/lisp/eshell/esh-proc-tests.el
+++ b/test/lisp/eshell/esh-proc-tests.el
@@ -191,6 +191,41 @@ esh-proc-test/pipeline-connection-type/last
      (unless (eq system-type 'windows-nt)
        "stdout\nstderr\n"))))
 
+
+;; Synchronous processes
+
+(ert-deftest esh-proc-test/synchronous-proc/simple/interactive ()
+  "Test that synchronous processes work in an interactive shell."
+  (skip-unless (executable-find "echo"))
+  (let ((eshell-supports-asynchronous-processes nil))
+    (with-temp-eshell
+     (eshell-match-command-output "*echo hello"
+                                  "\\`hello\n"))))
+
+(ert-deftest esh-proc-test/synchronous-proc/simple/command-result ()
+  "Test that synchronous processes work via `eshell-command-result'."
+  (skip-unless (executable-find "echo"))
+  (let ((eshell-supports-asynchronous-processes nil))
+    (eshell-command-result-equal "*echo hello"
+                                 "hello\n")))
+
+(ert-deftest esh-proc-test/synchronous-proc/pipeline/interactive ()
+  "Test that synchronous pipelines work in an interactive shell."
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "rev")))
+  (let ((eshell-supports-asynchronous-processes nil))
+    (with-temp-eshell
+     (eshell-match-command-output "*echo hello | *rev"
+                                  "\\`olleh\n"))))
+
+(ert-deftest esh-proc-test/synchronous-proc/pipeline/command-result ()
+  "Test that synchronous pipelines work via `eshell-command-result'."
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "rev")))
+  (let ((eshell-supports-asynchronous-processes nil))
+    (eshell-command-result-equal "*echo hello | *rev"
+                                 "olleh\n")))
+
 
 ;; Killing processes
 
-- 
2.25.1