emacs-29 6419d78fa6f: Fix using background commands in 'eshell-command'

[Jim Porter]

branch: emacs-29
commit 6419d78fa6f8a7794893da5a8a5d65f75a5a29fa
Author: Jim Porter <jporterbugs@gmail.com>
Commit: Jim Porter <jporterbugs@gmail.com>

    Fix using background commands in 'eshell-command'
    
    Do not merge to master.
    
    This regressed due to the patch for bug#53715, which changed how
    Eshell pipelines return the processes in the pipeline (bug#62556).
    
    * lisp/eshell/esh-cmd.el (eshell-eval-command): Allow process-pairs.
    
    * test/lisp/eshell/eshell-tests.el (eshell-test/eshell-command/simple)
    (eshell-test/eshell-command/pipeline)
    (eshell-test/eshell-command/background)
    (eshell-test/eshell-command/background-pipeline): New tests.
---
 lisp/eshell/esh-cmd.el           |  8 ++++---
 test/lisp/eshell/eshell-tests.el | 47 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 52 insertions(+), 3 deletions(-)

diff --git a/lisp/eshell/esh-cmd.el b/lisp/eshell/esh-cmd.el
index f4ac384ccc5..706477a5f45 100644
--- a/lisp/eshell/esh-cmd.el
+++ b/lisp/eshell/esh-cmd.el
@@ -1032,18 +1032,20 @@ produced by `eshell-parse-command'."
     (setq eshell-current-command command)
     (let* ((delim (catch 'eshell-incomplete
                     (eshell-resume-eval)))
-           (val (car-safe delim)))
+           (val (car-safe delim))
+           (val-is-process (or (eshell-processp val)
+                               (eshell-process-pair-p val))))
       ;; If the return value of `eshell-resume-eval' is wrapped in a
       ;; list, it indicates that the command was run asynchronously.
       ;; In that case, unwrap the value before checking the delimiter
       ;; value.
       (if (and val
-               (not (eshell-processp val))
+               (not val-is-process)
                (not (eq val t)))
           (error "Unmatched delimiter: %S" val)
         ;; Eshell-command expect a list like (<process>) to know if the
         ;; command should be async or not.
-        (or (and (eshell-processp val) delim) val)))))
+        (or (and val-is-process delim) val)))))
 
 (defun eshell-resume-command (proc status)
   "Resume the current command when a process ends."
diff --git a/test/lisp/eshell/eshell-tests.el b/test/lisp/eshell/eshell-tests.el
index 3c4a8ec97ea..b57abe3226c 100644
--- a/test/lisp/eshell/eshell-tests.el
+++ b/test/lisp/eshell/eshell-tests.el
@@ -105,6 +105,53 @@
      (format template "format \"%s\" eshell-in-pipeline-p")
      "nil")))
 
+(ert-deftest eshell-test/eshell-command/simple ()
+  "Test that the `eshell-command' function writes to the current buffer."
+  (skip-unless (executable-find "echo"))
+  (ert-with-temp-directory eshell-directory-name
+    (let ((eshell-history-file-name nil))
+      (with-temp-buffer
+        (eshell-command "*echo hi" t)
+        (should (equal (buffer-string) "hi\n"))))))
+
+(ert-deftest eshell-test/eshell-command/pipeline ()
+  "Test that the `eshell-command' function writes to the current buffer.
+This test uses a pipeline for the command."
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "cat")))
+  (ert-with-temp-directory eshell-directory-name
+    (let ((eshell-history-file-name nil))
+      (with-temp-buffer
+        (eshell-command "*echo hi | *cat" t)
+        (should (equal (buffer-string) "hi\n"))))))
+
+(ert-deftest eshell-test/eshell-command/background ()
+  "Test that `eshell-command' works for background commands."
+  (skip-unless (executable-find "echo"))
+  (ert-with-temp-directory eshell-directory-name
+    (let ((eshell-history-file-name nil))
+      ;; XXX: We can't write to the current buffer here, since
+      ;; `eshell-command' will produce an invalid command in that
+      ;; case.  Just make sure the command runs and produces an output
+      ;; buffer.
+      (eshell-command "*echo hi &")
+      (with-current-buffer "*Eshell Async Command Output*"
+        (goto-char (point-min))
+        (should (looking-at "\\[echo\\(<[0-9]+>\\)?\\]"))))))
+
+(ert-deftest eshell-test/eshell-command/background-pipeline ()
+  "Test that `eshell-command' works for background commands.
+This test uses a pipeline for the command."
+  (skip-unless (and (executable-find "echo")
+                    (executable-find "cat")))
+  (ert-with-temp-directory eshell-directory-name
+    (let ((eshell-history-file-name nil))
+      ;; XXX: As above, we can't write to the current buffer here.
+      (eshell-command "*echo hi | *cat &")
+      (with-current-buffer "*Eshell Async Command Output*"
+        (goto-char (point-min))
+        (should (looking-at "\\[cat\\(<[0-9]+>\\)?\\]"))))))
+
 (ert-deftest eshell-test/command-running-p ()
   "Modeline should show no command running"
   (with-temp-eshell