>From 174673f0d98b1042ef10a3307bc3956c17b41100 Mon Sep 17 00:00:00 2001
From: John Shahid <address@hidden>
Date: Mon, 29 Apr 2019 13:53:38 -0400
Subject: [PATCH] Fix setting and unsetting scroll-with-delete

* lisp/term.el (term-set-scroll-region): Do not set
  term-scroll-with-delete when the region is set to the height of the
  terminal.
* lisp/term.el (term-reset-terminal): Reset term-scroll-with-delete.
* test/lisp/term-tests.el (term-scrolling-region): Add more tests to
  term mode handle scroll region properly.
---
 lisp/term.el            |  5 +--
 test/lisp/term-tests.el | 78 ++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 80 insertions(+), 3 deletions(-)

diff --git a/lisp/term.el b/lisp/term.el
index d69ab94b7a..1fe27da181 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -1174,7 +1174,7 @@ term-reset-size
       (setq term-start-line-column nil)
       (setq term-current-row nil)
       (setq term-current-column nil)
-      (term-set-scroll-region 0 height)
+      (term-set-scroll-region 0 (1- height))
       ;; `term-set-scroll-region' causes these to be set, we have to
       ;; clear them again since we're changing point (Bug#30544).
       (setq term-start-line-column nil)
@@ -3215,6 +3215,7 @@ term-reset-terminal
   (setq term-current-column 1)
   (setq term-scroll-start 0)
   (setq term-scroll-end term-height)
+  (setq term-scroll-with-delete nil)
   (setq term-insert-mode nil)
   ;; FIXME: No idea why this is here, it looks wrong.  --Stef
   (setq term-ansi-face-already-done nil))
@@ -3439,7 +3440,7 @@ term-set-scroll-region
   (setq term-scroll-with-delete
 	(or (term-using-alternate-sub-buffer)
 	    (not (and (= term-scroll-start 0)
-		      (= term-scroll-end term-height)))))
+                      (= term-scroll-end (1- term-height))))))
   (term-move-columns (- (term-current-column)))
   (term-goto 0 0))
 
diff --git a/test/lisp/term-tests.el b/test/lisp/term-tests.el
index 9f5dcd559e..b0b9a11974 100644
--- a/test/lisp/term-tests.el
+++ b/test/lisp/term-tests.el
@@ -119,7 +119,83 @@ term-test-screen-from-input
 line4\r
 line5\r
 line6\r
-"))))
+")))
+
+  ;; test reverse scrolling
+  (should (equal "line1
+line7
+line6
+line2
+line5"
+                 (term-test-screen-from-input 40 5
+                                              '("\e[0;0H"
+                                                "\e[J"
+                                                "line1\r
+line2\r
+line3\r
+line4\r
+line5"
+                                                "\e[2;4r"
+                                                "\e[2;0H"
+                                                "\e[2;0H"
+                                                "\eMline6"
+                                                "\e[2;0H"
+                                                "\eMline7"))))
+
+  ;; test scrolling down
+  (should (equal "line1
+line3
+line4
+line7
+line5"
+                 (term-test-screen-from-input 40 5
+                                              '("\e[0;0H"
+                                                "\e[J"
+                                                "line1\r
+line2\r
+line3\r
+line4\r
+line5"
+                                                "\e[2;4r"
+                                                "\e[2;0H"
+                                                "\e[4;5H"
+                                                "\n\rline7"))))
+
+  ;; setting the scroll region to the entire height should not turn on
+  ;; term-scroll-with-delete
+  (should (equal "line1
+line2
+line3
+line4
+line5
+line6"
+                 (term-test-screen-from-input 40 5
+                                                      '("\e[1;5r"
+                                                        "line1\r
+line2\r
+line3\r
+line4\r
+line5\r
+line6"))))
+
+  ;; reset should reset term-scroll-with-delete
+  (should (equal "line1
+line2
+line3
+line4
+line5
+line6
+line7"
+                 (term-test-screen-from-input 40 5
+                                              '("\e[2;5r" ;set the region
+                                                "\ec" ;reset
+                                                "line1\r
+line2\r
+line3\r
+line4\r
+line5\r
+line6\r
+line7")))))
 
 (ert-deftest term-set-directory ()
   (let ((term-ansi-at-user (user-real-login-name)))
-- 
2.21.0