fix(custom-line-paragraph): correct paren-jump, line-join, and duplicate

This module carried three editing bugs.

cj/jump-to-matching-paren, with point on a closing delimiter, ran backward-sexp from there and landed on the last inner sexp instead of the opener. It now steps past the closer first so backward-sexp spans the whole expression, and restores point when the delimiter is unmatched. Four tests that asserted the last-inner-sexp landings are corrected to the true matching opener.

cj/join-line-or-region, without a region, added a newline unconditionally after joining, which left a stray blank line when joining a line in the middle of the buffer. It now adds the newline only at end of buffer.

cj/duplicate-line-or-region duplicated a stray empty line for a region ending at beginning-of-line and split the line for a region ending mid-line. I normalized the bounds to the whole lines the region touches and insert that block once.

1 files changed, 16 insertions, 2 deletions

diff --git a/tests/test-custom-line-paragraph-join-line-or-region.el b/tests/test-custom-line-paragraph-join-line-or-region.el
index f8738910..5d421683 100644
--- a/tests/test-custom-line-paragraph-join-line-or-region.el
+++ b/tests/test-custom-line-paragraph-join-line-or-region.el
@@ -62,8 +62,8 @@
         (should (string-match-p "line one line two" (buffer-string))))
     (test-join-line-or-region-teardown)))
 
-(ert-deftest test-join-line-or-region-no-region-adds-newline-after-join ()
-  "Without region, should add newline after joining."
+(ert-deftest test-join-line-or-region-no-region-adds-newline-at-end-of-buffer ()
+  "Without region, joining the last line adds a trailing newline at end of buffer."
   (test-join-line-or-region-setup)
   (unwind-protect
       (with-temp-buffer
@@ -73,6 +73,20 @@
         (should (string-suffix-p "\n" (buffer-string))))
     (test-join-line-or-region-teardown)))
 
+(ert-deftest test-join-line-or-region-no-region-mid-buffer-no-blank-line ()
+  "Without region, joining a non-last line must not insert a blank line.
+The trailing newline belongs only at end of buffer; adding it unconditionally
+left a stray blank line between the joined line and the rest of the buffer."
+  (test-join-line-or-region-setup)
+  (unwind-protect
+      (with-temp-buffer
+        (insert "line one\nline two\nline three")
+        (goto-char (point-min))
+        (forward-line 1)                ; point on "line two", not the last line
+        (cj/join-line-or-region)
+        (should (string= "line one line two\nline three" (buffer-string))))
+    (test-join-line-or-region-teardown)))
+
 (ert-deftest test-join-line-or-region-with-region-joins-all-lines ()
   "With region, should join all lines in region."
   (test-join-line-or-region-setup)