undo-tests.el: Tests for bug#60467

* test/src/undo-tests.el (undo-test-combine-change-calls-1)
(undo-test-combine-change-calls-2, undo-test-combine-change-calls-3):
New tests.

1 files changed, 72 insertions, 0 deletions

diff --git a/test/src/undo-tests.el b/test/src/undo-tests.el
index 84151d3b5db..fd45a9101fa 100644
--- a/test/src/undo-tests.el
+++ b/test/src/undo-tests.el
@@ -439,6 +439,78 @@ Demonstrates bug 16818."
 
     (should (string= (buffer-string) "aaaFirst line\nSecond line\nbbb"))))
 
+(ert-deftest undo-test-combine-change-calls-1 ()
+  "Test how `combine-change-calls' updates `buffer-undo-list'.
+Case 1: a file-visiting buffer with `buffer-undo-list' non-nil
+and `buffer-modified-p' non-nil when `combine-change-calls' is
+called."
+  (ert-with-temp-file tempfile
+    (with-current-buffer (find-file tempfile)
+      (insert "A")
+      (undo-boundary)
+      (insert "B")
+      (undo-boundary)
+      (insert "C")
+      (undo-boundary)
+      (insert " ")
+      (undo-boundary)
+      (insert "D")
+      (undo-boundary)
+      (insert "E")
+      (undo-boundary)
+      (insert "F")
+      (should (= (length buffer-undo-list) 14))
+      (goto-char (point-min))
+      (combine-change-calls (point-min) (point-max)
+        (re-search-forward "ABC ")
+        (replace-match "Z "))
+      (should (= (length buffer-undo-list) 15)))))
+
+(ert-deftest undo-test-combine-change-calls-2 ()
+  "Test how `combine-change-calls' updates `buffer-undo-list'.
+Case 2: a file-visiting buffer with `buffer-undo-list' non-nil
+and `buffer-modified-p' nil when `combine-change-calls' is
+called."
+  (ert-with-temp-file tempfile
+    (with-current-buffer (find-file tempfile)
+      (insert "A")
+      (undo-boundary)
+      (insert "B")
+      (undo-boundary)
+      (insert "C")
+      (undo-boundary)
+      (insert " ")
+      (undo-boundary)
+      (insert "D")
+      (undo-boundary)
+      (insert "E")
+      (undo-boundary)
+      (insert "F")
+      (should (= (length buffer-undo-list) 14))
+      (save-buffer)
+      (goto-char (point-min))
+      (combine-change-calls (point-min) (point-max)
+        (re-search-forward "ABC ")
+        (replace-match "Z "))
+      (should (= (length buffer-undo-list) 15)))))
+
+(ert-deftest undo-test-combine-change-calls-3 ()
+  "Test how `combine-change-calls' updates `buffer-undo-list'.
+Case 3: a file-visiting buffer with `buffer-undo-list' nil and
+`buffer-modified-p' nil when `combine-change-calls' is called."
+  (ert-with-temp-file tempfile
+    (with-current-buffer (find-file tempfile)
+      (insert "ABC DEF")
+      (save-buffer)
+      (kill-buffer))
+    (with-current-buffer (find-file tempfile)
+      (should (= (length buffer-undo-list) 0))
+      (goto-char (point-min))
+      (combine-change-calls (point-min) (point-max)
+        (re-search-forward "ABC ")
+        (replace-match "Z "))
+      (should (= (length buffer-undo-list) 1)))))
+
 (defun undo-test-all (&optional interactive)
   "Run all tests for \\[undo]."
   (interactive "p")