From 22f8de0f4f9b60ba3c6d3cc164cdf07ff988d2a4 Mon Sep 17 00:00:00 2001
From: Bryce Kwon <bryce@brycekwon.com>
Date: Sat, 31 Oct 2026 22:07:47 -1000
Subject: Show a renamed file's diff as the rename

A diff limited to the new name cannot see the old one, so the
diffstat's link for a renamed file, the commit page reached from that
file's log, and the file's rawdiff and patch all showed every line as
added. A path the old tree lacks is now diffed across the whole commit
with rename detection aimed at it alone, the way git blame looks for a
rename, so it is compared with the commit's deleted files and nothing
else. Doing it in cgit_diff_tree keeps the log's counts for that commit
in step with the page they link to.

The rawdiff and patch pages leave the diff to git's own output, so for
them that search finds the old name, and both names go into the limit
with rename detection on.
---
 tests/t0107-diff.sh | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

(limited to 'tests/t0107-diff.sh')

diff --git a/tests/t0107-diff.sh b/tests/t0107-diff.sh
index e173d00..d03ecd2 100755
--- a/tests/t0107-diff.sh
+++ b/tests/t0107-diff.sh
@@ -104,4 +104,39 @@ test_expect_success 'stripping the highlight leaves every line intact' '
 	done <lines
 '
 
+# The diffstat links a renamed file by its new name, and so does the log of
+# that file, but the old name lies outside a diff limited to the new one.
+test_expect_success 'set up a renamed file' '
+	mkrepo repos/moved 1 &&
+	(
+		cd repos/moved &&
+		test_seq 1 10 >old.txt &&
+		git add old.txt &&
+		git commit -m "add old.txt" &&
+		git mv old.txt new.txt &&
+		git commit -m "rename old.txt"
+	) &&
+	cgitrc_repo movedrc moved
+'
+
+test_expect_success 'the diff of a renamed file shows the rename' '
+	cgit_rc movedrc "url=moved/diff/new.txt" >tmp &&
+	grep "diff --git a/old.txt b/new.txt" tmp &&
+	grep "</a> (renamed from old.txt)</td>" tmp &&
+	! grep "new file mode" tmp
+'
+
+test_expect_success 'so does the commit page limited to the new name' '
+	cgit_rc movedrc "url=moved/commit/new.txt" >tmp &&
+	grep "diff --git a/old.txt b/new.txt" tmp &&
+	! grep "new file mode" tmp
+'
+
+test_expect_success 'a file added outright still shows as new' '
+	added=$(git -C repos/moved rev-parse HEAD~1) &&
+	cgit_rc movedrc "url=moved/diff/old.txt&id=$added" >tmp &&
+	grep "new file mode 100644" tmp &&
+	grep "<div class=.add.>+10</div>" tmp
+'
+
 test_done
-- 
cgit 2.12.1