1 files changed, 98 insertions, 0 deletions
diff --git a/test/automated/undo-tests.el b/test/automated/undo-tests.el
index 8a963f1002..6ecac36b6b 100644
--- a/test/automated/undo-tests.el
+++ b/test/automated/undo-tests.el
@@ -268,6 +268,104 @@
     (should (string= (buffer-string)
                      "This sentence corrupted?aaa"))))
 
+(ert-deftest undo-test-marker-adjustment-nominal ()
+  "Test nominal behavior of marker adjustments."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (insert "abcdefg")
+    (undo-boundary)
+    (let ((m (make-marker)))
+      (set-marker m 2 (current-buffer))
+      (goto-char (point-min))
+      (delete-forward-char 3)
+      (undo-boundary)
+      (should (= (point-min) (marker-position m)))
+      (undo)
+      (undo-boundary)
+      (should (= 2 (marker-position m))))))
+
+(ert-deftest undo-test-region-t-marker ()
+  "Test undo in region containing marker with t insertion-type."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (transient-mark-mode 1)
+    (insert "abcdefg")
+    (undo-boundary)
+    (let ((m (make-marker)))
+      (set-marker-insertion-type m t)
+      (set-marker m (point-min) (current-buffer)) ; m at a
+      (goto-char (+ 2 (point-min)))
+      (push-mark (point) t t)
+      (setq mark-active t)
+      (goto-char (point-min))
+      (delete-forward-char 1) ;; delete region covering "ab"
+      (undo-boundary)
+      (should (= (point-min) (marker-position m)))
+      ;; Resurrect "ab". m's insertion type means the reinsertion
+      ;; moves it forward 2, and then the marker adjustment returns it
+      ;; to its rightful place.
+      (undo)
+      (undo-boundary)
+      (should (= (point-min) (marker-position m))))))
+
+(ert-deftest undo-test-marker-adjustment-moved ()
+  "Test marker adjustment behavior when the marker moves.
+Demonstrates bug 16818."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (insert "abcdefghijk")
+    (undo-boundary)
+    (let ((m (make-marker)))
+      (set-marker m 2 (current-buffer)) ; m at b
+      (goto-char (point-min))
+      (delete-forward-char 3) ; m at d
+      (undo-boundary)
+      (set-marker m 4) ; m at g
+      (undo)
+      (undo-boundary)
+      ;; m still at g, but shifted 3 because deletion undone
+      (should (= 7 (marker-position m))))))
+
+(ert-deftest undo-test-region-mark-adjustment ()
+  "Test that the mark's marker adjustment in undo history doesn't
+obstruct undo in region from finding the correct change group.
+Demonstrates bug 16818."
+  (with-temp-buffer
+    (buffer-enable-undo)
+    (transient-mark-mode 1)
+    (insert "First line\n")
+    (insert "Second line\n")
+    (undo-boundary)
+
+    (goto-char (point-min))
+    (insert "aaa")
+    (undo-boundary)
+
+    (undo)
+    (undo-boundary)
+
+    (goto-char (point-max))
+    (insert "bbb")
+    (undo-boundary)
+
+    (push-mark (point) t t)
+    (setq mark-active t)
+    (goto-char (- (point) 3))
+    (delete-forward-char 1)
+    (undo-boundary)
+
+    (insert "bbb")
+    (undo-boundary)
+
+    (goto-char (point-min))
+    (push-mark (point) t t)
+    (setq mark-active t)
+    (goto-char (+ (point) 3))
+    (undo)
+    (undo-boundary)
+
+    (should (string= (buffer-string) "aaaFirst line\nSecond line\nbbb"))))
+
 (defun undo-test-all (&optional interactive)
   "Run all tests for \\[undo]."
   (interactive "p")