[no-release-notes] add test for reverse keyless index read

Author: max-hoffman

enginetest/queries/script_queries.go

@@ -107,6 +107,17 @@ type ScriptTestAssertion struct {
 // Unlike other engine tests, ScriptTests must be self-contained. No other tables are created outside the definition of
 // the tests.
 var ScriptTests = []ScriptTest{
+	{
+		Name: "keyless reverse index",
+		SetUpScript: []string{
+			"create table x (x int, key(x));",
+			"insert into x values (0),(1)",
+		},
+		Query: "select * from x order by x desc limit 1",
+		Expected: []sql.Row{
+			{1},
+		},
+	},
 	{
 		Name: "filter pushdown through join uppercase name",
 		SetUpScript: []string{