libsyntax: fix for has_test_signature

Author: blackbeam

src/libsyntax/test.rs

@@ -295,6 +295,7 @@ fn is_test_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
           &ast::ItemFn(ref decl, _, _, ref generics, _) => {
             let no_output = match decl.output {
                 ast::DefaultReturn(..) => true,
+                ast::Return(ref t) if t.node == ast::TyTup(vec![]) => true,
                 _ => false
             };
             if decl.inputs.is_empty()
@@ -331,6 +332,7 @@ fn is_bench_fn(cx: &TestCtxt, i: &ast::Item) -> bool {
                 let input_cnt = decl.inputs.len();
                 let no_output = match decl.output {
                     ast::DefaultReturn(..) => true,
+                    ast::Return(ref t) if t.node == ast::TyTup(vec![]) => true,
                     _ => false
                 };
                 let tparm_cnt = generics.ty_params.len();