[PATCH 2/3] t4054: test diff --no-index with stdin

[Phillip Wood <phillip.wood123@gmail.com>]

From: Phillip Wood <phillip.wood@dunelm.org.uk>

"git diff --no-index" supports reading from stdin with the path "-".
There is no test coverage for this so add a regression test before
changing the code in the next commit.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
---
 t/t4053-diff-no-index.sh | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/t/t4053-diff-no-index.sh b/t/t4053-diff-no-index.sh
index 4e9fa0403d..d14b194ea2 100755
--- a/t/t4053-diff-no-index.sh
+++ b/t/t4053-diff-no-index.sh
@@ -205,4 +205,22 @@ test_expect_success POSIXPERM,SYMLINKS 'diff --no-index normalizes: mode not lik
 	test_cmp expected actual
 '
 
+test_expect_success "diff --no-index treats '-' as stdin" '
+	cat >expect <<-EOF &&
+	diff --git a/- b/a/1
+	index $ZERO_OID..$(git hash-object --stdin <a/1) 100644
+	--- a/-
+	+++ b/a/1
+	@@ -1 +1 @@
+	-x
+	+1
+	EOF
+
+	test_write_lines x | test_expect_code 1 \
+		git -c core.abbrev=no diff --no-index -- - a/1 >actual &&
+	test_cmp expect actual &&
+
+	test_write_lines 1 | git diff --no-index -- a/1 - >actual &&
+	test_must_be_empty actual
+'
 test_done
-- 
2.40.1.852.g22d29fd9ba