query-replace: Undo replacements performed with 'comma

During a `query-replace', the char ',' replaces the character
at point and doesn't move point;  right after, the char 'u'
must undo such replacement (Bug#27268).
* lisp/replace.el (replace--push-stack):
New macro extracted from `perform-replace'.
(perform-replace): Use it.
* test/lisp/replace-tests.el (query-replace--undo): Add test.

1 files changed, 22 insertions, 0 deletions

diff --git a/test/lisp/replace-tests.el b/test/lisp/replace-tests.el
index adef5a3f3dc..a8bc5407f42 100644
--- a/test/lisp/replace-tests.el
+++ b/test/lisp/replace-tests.el
@@ -358,4 +358,26 @@ Each element has the format:
 (dotimes (i (length replace-occur-tests))
   (replace-occur-test-create i))
 
+(defun replace-tests--query-replace-undo (&optional comma)
+  (with-temp-buffer
+    (insert "111")
+    (goto-char 1)
+    (let ((count 0))
+      ;; Don't wait for user input.
+      (cl-letf (((symbol-function 'read-event)
+                 (lambda (&rest args)
+                   (cl-incf count)
+                   (let ((val (pcase count
+                                ('2 (if comma ?, ?\s)) ; replace and: ',' no move; '\s' go next
+                                ('3 ?u) ; undo
+                                ('4 ?q) ; exit
+                                (_ ?\s)))) ; replace current and go next
+                     val))))
+        (perform-replace "1" "2" t nil nil)))
+    (buffer-string)))
+
+(ert-deftest query-replace--undo ()
+  (should (string= "211" (replace-tests--query-replace-undo)))
+  (should (string= "211" (replace-tests--query-replace-undo 'comma))))
+
 ;;; replace-tests.el ends here