1 files changed, 37 insertions, 0 deletions
diff --git a/t/t4254-am-corrupt.sh b/t/t4254-am-corrupt.sh
new file mode 100755
index 0000000000..85716dd6ec
--- /dev/null
+++ b/t/t4254-am-corrupt.sh
@@ -0,0 +1,37 @@
+#!/bin/sh
+
+test_description='git am with corrupt input'
+. ./test-lib.sh
+
+test_expect_success setup '
+	# Note the missing "+++" line:
+	cat >bad-patch.diff <<-\EOF &&
+	From: A U Thor <au.thor@example.com>
+	diff --git a/f b/f
+	index 7898192..6178079 100644
+	--- a/f
+	@@ -1 +1 @@
+	-a
+	+b
+	EOF
+
+	echo a >f &&
+	git add f &&
+	test_tick &&
+	git commit -m initial
+'
+
+# This used to fail before, too, but with a different diagnostic.
+#   fatal: unable to write file '(null)' mode 100644: Bad address
+# Also, it had the unwanted side-effect of deleting f.
+test_expect_success 'try to apply corrupted patch' '
+	test_must_fail git am bad-patch.diff 2>actual
+'
+
+test_expect_success 'compare diagnostic; ensure file is still here' '
+	echo "fatal: git diff header lacks filename information (line 4)" >expected &&
+	test_path_is_file f &&
+	test_cmp expected actual
+'
+
+test_done