From 840115bf46476dc2b3c175f7716b4d6000906f40 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Mon, 20 Jul 2020 13:38:37 +0900
Subject: [PATCH] Make StringIO encoding fixed

Get rid of affects by default external encoding.
---
 spec/ruby/core/kernel/printf_spec.rb      | 4 ++--
 spec/ruby/library/stringio/printf_spec.rb | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/spec/ruby/core/kernel/printf_spec.rb b/spec/ruby/core/kernel/printf_spec.rb
index d1743dbcde..d8f93ce429 100644
--- a/spec/ruby/core/kernel/printf_spec.rb
+++ b/spec/ruby/core/kernel/printf_spec.rb
@@ -41,7 +41,7 @@ describe "Kernel.printf" do
 
     context "io is specified" do
       it_behaves_like :kernel_sprintf, -> format, *args {
-        io = StringIO.new
+        io = StringIO.new(+"")
         Kernel.printf(io, format, *args)
         io.string
       }
@@ -51,7 +51,7 @@ describe "Kernel.printf" do
       it_behaves_like :kernel_sprintf, -> format, *args {
         stdout = $stdout
         begin
-          $stdout = io = StringIO.new
+          $stdout = io = StringIO.new(+"")
           Kernel.printf(format, *args)
           io.string
         ensure
diff --git a/spec/ruby/library/stringio/printf_spec.rb b/spec/ruby/library/stringio/printf_spec.rb
index f88ca1eb20..9dd1a3b410 100644
--- a/spec/ruby/library/stringio/printf_spec.rb
+++ b/spec/ruby/library/stringio/printf_spec.rb
@@ -32,7 +32,7 @@ describe "StringIO#printf" do
 
   describe "formatting" do
     it_behaves_like :kernel_sprintf, -> format, *args {
-      io = StringIO.new
+      io = StringIO.new(+"")
       io.printf(format, *args)
       io.string
     }