Re: emacs-26 b3e2073 4/4: Fix subproc listening when setting filter to non-t (Bug#36591)

[Noam Postavsky <npostavs@gmail.com>]

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On Thu, 22 Aug 2019 at 15:12, Michael Albinus <michael.albinus@gmx.de> wrote:

> > +      (should
> > +       (accept-process-output proc 1))  ; Read "one".
> > +      (should (equal (buffer-string) "$ one\n$ "))

> This fails on emba occasionally, see for example
> <https://emba.gnu.org/emacs/emacs/-/jobs/3076>.

Ah right, I wrongly assumed all the output would come in a single
chunk. Attached patch should fix it, should I push to emacs-26 since
tests are not included in the tarball release anyway? Or...?

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From 1c1def35e9d46dd8e0e38589b768477f917d9bec Mon Sep 17 00:00:00 2001
From: Noam Postavsky <npostavs@gmail.com>
Date: Thu, 22 Aug 2019 20:48:19 -0400
Subject: [PATCH] Fix non-deterministic process test

* test/src/process-tests.el (set-process-filter-t): Don't assume
subprocess output will come in a single chunk, keep waiting for more
data until next "prompt" is read from subprocess.
---
 test/src/process-tests.el | 26 ++++++++++++++++----------
 1 file changed, 16 insertions(+), 10 deletions(-)

diff --git a/test/src/process-tests.el b/test/src/process-tests.el
index 7a6762a922..ef057af6b7 100644
--- a/test/src/process-tests.el
+++ b/test/src/process-tests.el
@@ -154,24 +154,30 @@ set-process-filter-t
                   (concat invocation-directory invocation-name)
                   "-Q" "--batch" "--eval"
                   (prin1-to-string
-                   '(let (s)
-                      (while (setq s (read-from-minibuffer "$ "))
+                   '(let ((s nil) (count 0))
+                      (while (setq s (read-from-minibuffer
+                                      (format "%d> " count)))
                         (princ s)
-                        (princ "\n")))))))
+                        (princ "\n")
+                        (setq count (1+ count))))))))
       (set-process-query-on-exit-flag proc nil)
       (send-string proc "one\n")
-      (should
-       (accept-process-output proc 1))  ; Read "one".
-      (should (equal (buffer-string) "$ one\n$ "))
+      (while (not (equal (buffer-substring
+                          (line-beginning-position) (point-max))
+                         "1> "))
+        (accept-process-output proc))   ; Read "one".
+      (should (equal (buffer-string) "0> one\n1> "))
       (set-process-filter proc t)       ; Stop reading from proc.
       (send-string proc "two\n")
       (should-not
        (accept-process-output proc 1))  ; Can't read "two" yet.
-      (should (equal (buffer-string) "$ one\n$ "))
+      (should (equal (buffer-string) "0> one\n1> "))
       (set-process-filter proc nil)     ; Resume reading from proc.
-      (should
-       (accept-process-output proc 1))  ; Read "two" from proc.
-      (should (equal (buffer-string) "$ one\n$ two\n$ ")))))
+      (while (not (equal (buffer-substring
+                          (line-beginning-position) (point-max))
+                         "2> "))
+        (accept-process-output proc))   ; Read "Two".
+      (should (equal (buffer-string) "0> one\n1> two\n2> ")))))
 
 (ert-deftest start-process-should-not-modify-arguments ()
   "`start-process' must not modify its arguments in-place."
-- 
2.11.0