(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")