1 file changed, 106 insertions, 18 deletions
diff --git a/tests/t0107-diff.sh b/tests/t0107-diff.sh
index 861ca44..f069894 100755
--- a/tests/t0107-diff.sh
+++ b/tests/t0107-diff.sh
@@ -114,25 +114,113 @@ test_expect_success 'set up a repo with shrinking changed lines' '
 	cgitrc_repo lcsrc lcs
 '
 
+# Each side of a row is written on a line of its own, the old side first and
+# the new side closing the row.
 test_expect_success 'every changed pair gets both a del and an add span' '
-	cgit_rc lcsrc "url=lcs/diff/&dt=1" >tmp &&
-	deletions=$(grep -o "<span class=.del.>" tmp | wc -l) &&
-	additions=$(grep -o "<span class=.add.>" tmp | wc -l) &&
-	test "$deletions" -gt 0 &&
-	test "$deletions" -eq "$additions"
-'
-
-test_expect_success 'stripping the highlight leaves every line intact' '
-	sed -e "s/<[^>]*>//g" tmp >plain.out &&
-	git -C repos/lcs show HEAD~1:lines.txt >lines &&
-	git -C repos/lcs show HEAD:lines.txt >>lines &&
-	while read -r line
-	do
-		grep -qF "$line" plain.out || {
-			echo "missing line: $line"
-			return 1
-		}
-	done <lines
+	cgit_ok lcsrc "url=lcs/diff/&dt=1" >tmp &&
+	test $(grep -c "^<td class=.lineno.>.*<td class=.changed.>.*<span class=.del.>.*</td>$" tmp) -eq 40 &&
+	test $(grep -c "^<td class=.lineno.>.*<td class=.changed.>.*<span class=.add.>.*</td></tr>$" tmp) -eq 40
+'
+
+test_expect_success 'stripping the highlight leaves each side its own lines' '
+	cgit_ok lcsrc "url=lcs/diff/&dt=1" >tmp &&
+	sed -n "s/^<td class=.lineno.><a [^>]*>[0-9]*<\/a><\/td><td class=.changed.>\(.*\)<\/td>$/\1/p" tmp |
+		sed "s/<[^>]*>//g" >old.out &&
+	sed -n "s/^<td class=.lineno.><a [^>]*>[0-9]*<\/a><\/td><td class=.changed.>\(.*\)<\/td><\/tr>$/\1/p" tmp |
+		sed "s/<[^>]*>//g" >new.out &&
+	git -C repos/lcs show HEAD~1:lines.txt >expect &&
+	test_cmp expect old.out &&
+	git -C repos/lcs show HEAD:lines.txt >expect &&
+	test_cmp expect new.out
+'
+
+# Comparing the second pair below reads cells the first one wrote, and a cell
+# left over from it would tip a tie there and mark the wrong characters.
+test_expect_success 'a short pair after a longer one marks its own characters' '
+	mkrepo repos/pair 1 &&
+	(
+		cd repos/pair &&
+		test_write_lines bcde xa >pair.txt &&
+		git add pair.txt &&
+		git commit -m "add pair.txt" &&
+		test_write_lines abcd ax >pair.txt &&
+		git commit -am "change pair.txt"
+	) &&
+	cgitrc_repo pairrc pair &&
+	cgit_ok pairrc "url=pair/diff/&dt=1" >tmp &&
+	sed -n "s/^<td class=.lineno.><a [^>]*>[0-9]*<\/a><\/td>//p" tmp | tr -d "\047" >actual &&
+	cat >expect <<-\EOF &&
+	<td class=changed>bcd<span class=del>e</span></td>
+	<td class=changed><span class=add>a</span>bcd</td></tr>
+	<td class=changed><span class=del>x</span>a</td>
+	<td class=changed>a<span class=add>x</span></td></tr>
+	EOF
+	test_cmp expect actual
+'
+
+# A file added or deleted fills one side, leaving the other a darker blank,
+# and a changed pair with nothing in common is marked whole. Forced colours
+# drop the backgrounds, so those cells keep a thicker border instead.
+test_expect_success 'each side of a row is classed by what it holds' '
+	cgit_ok_url "foo/diff&dt=1" >tmp &&
+	grep -x "<td class=.lineno.></td><td class=.add-dark.></td>" tmp &&
+	grep "<td class=.add.>5</td></tr>" tmp &&
+	cgit_ok hunk1rc "url=hunk1/diff/&dt=1" >tmp &&
+	grep "</a></td><td class=.changed.><span class=.del.>only</span></td>$" tmp &&
+	grep "</a></td><td class=.changed.><span class=.add.>ONLY</span></td></tr>$" tmp
+'
+
+test_expect_success 'forced colours mark the changed cells with a border' '
+	sed -n "/^@media (forced-colors: active) {$/,/^}/p" \
+		"$TEST_OUTPUT_DIRECTORY/../assets/cgit.css" >rule &&
+	sed -n "/^  div#cgit table.ssdiff td.add,$/,/^  }$/p" rule >cells &&
+	grep "^  div#cgit table.ssdiff td.del,$" cells &&
+	grep "^  div#cgit table.ssdiff td.changed {$" cells &&
+	grep "^    border-left-width: 4px;$" cells
+'
+
+# Removals and additions that do not pair off are shown without marking,
+# with a dark blank where a side runs out. A line past the comparison's
+# limit is shown whole, a tab is expanded, and a binary file says so.
+test_expect_success 'set up a commit for the remaining side-by-side rows' '
+	mkrepo repos/cells 1 &&
+	(
+		cd repos/cells &&
+		test_write_lines gone >gone.txt &&
+		test_write_lines one two keep >uneven.txt &&
+		printf "%0130d\n" 0 >long.txt &&
+		printf "a\tb\nx\n" >tab.txt &&
+		printf "\000old" >bin.dat &&
+		git add . &&
+		git commit -m "add the files" &&
+		git rm -q gone.txt &&
+		test_write_lines ONE keep >uneven.txt &&
+		printf "%0129d1\n" 0 >long.txt &&
+		printf "a\tb\ny\n" >tab.txt &&
+		printf "\000new" >bin.dat &&
+		git commit -am "change the files"
+	) &&
+	cgitrc_repo cellsrc cells
+'
+
+test_expect_success 'the remaining side-by-side rows' '
+	cgit_ok cellsrc "url=cells/diff/&dt=1" >tmp &&
+	grep "</a></td><td class=.del.>gone</td>$" tmp &&
+	grep -x "<td class=.lineno.></td><td class=.del-dark.></td></tr>" tmp &&
+	grep "</a></td><td class=.changed.>one</td>$" tmp &&
+	grep "</a></td><td class=.changed.>ONE</td></tr>$" tmp &&
+	grep "</a></td><td class=.changed.>two</td>$" tmp &&
+	grep -x "<td class=.lineno.></td><td class=.changed-dark.></td></tr>" tmp &&
+	grep "</a></td><td class=.changed.>$(printf "%0130d" 0)</td>$" tmp &&
+	grep "</a></td><td class=.changed.>$(printf "%0129d1" 0)</td></tr>$" tmp &&
+	grep "</a></td><td class=.ctx.>a       b</td>$" tmp &&
+	grep "<tr><td colspan=.4.>Binary files differ</td></tr>" tmp
+'
+
+test_expect_success 'a side-by-side diff past max-diff-lines is cut short' '
+	cgitrc_repo cellscaprc cells max-diff-lines=1 &&
+	cgit_ok cellscaprc "url=cells/diff/&dt=1" >tmp &&
+	grep "<tr><td colspan=.4. class=.truncated.>This diff is too large to be rendered inline. <a href=./cells/diff/long.txt?dt=1.>View it on its own page</a>.</td></tr>" tmp
 '
 
 # The diffstat links a renamed file by its new name, and so does the log of