diff --git a/lib/elf/object_writer.rb b/lib/elf/object_writer.rb
index 81b93740..9f33f4cb 100644
--- a/lib/elf/object_writer.rb
+++ b/lib/elf/object_writer.rb
@@ -67,10 +67,20 @@ module Elf
       @symbol_table.add_func_symbol name, offset, @text, linkage
     end
 
-    def save(filename)
-      to = File.open(filename, 'wb')
-      @object.write to
-      to.close
+    # save to either file or io
+    # Pass Filename as string
+    # or any io object
+    def save(file)
+      case file
+      when String
+        io = File.open(file, 'wb')
+      when IO , StringIO
+        io = file
+      else
+        raise "must pass io or filename, not #{file}"
+      end
+      @object.write io
+      io.close
     end
 
   end
diff --git a/test/elf/helper.rb b/test/elf/helper.rb
index 490d2d04..f9ed6d47 100644
--- a/test/elf/helper.rb
+++ b/test/elf/helper.rb
@@ -10,10 +10,10 @@ module Elf
     def as_main(input)
       in_space("def main(arg);#{input};end")
     end
-    def check(input, file)
+    def check(input)
       linker = RubyX::RubyXCompiler.new(RubyX.default_test_options).ruby_to_binary( input , :arm )
       writer = Elf::ObjectWriter.new(linker)
-      writer.save "test/#{file}.o"
+      writer.save StringIO.new
     end
   end
 end
diff --git a/test/elf/test_something.rb b/test/elf/test_something.rb
index 24452ec4..cdf14b4d 100644
--- a/test/elf/test_something.rb
+++ b/test/elf/test_something.rb
@@ -23,7 +23,7 @@ module Elf
       end
 HERE
       @exit_code = 4
-      check get_preload("Integer.lt;Integer.plus") + in_space(input) , "fibo"
+      check get_preload("Integer.lt;Integer.plus") + in_space(input) 
     end
   end
 end
diff --git a/test/elf/test_somethingelse.rb b/test/elf/test_somethingelse.rb
index f1c116de..dc0ac246 100644
--- a/test/elf/test_somethingelse.rb
+++ b/test/elf/test_somethingelse.rb
@@ -9,7 +9,7 @@ module Elf
       preload = "class Word < Data8;def putstring;X.putstring;end;end;"
       @stdout = hello
       @exit_code = hello.length
-      check preload + as_main(input), "hello"
+      check preload + as_main(input)
     end
   end
 end
diff --git a/test/elf/test_zero.rb b/test/elf/test_zero.rb
index bb5aa800..6c7af5cb 100644
--- a/test/elf/test_zero.rb
+++ b/test/elf/test_zero.rb
@@ -11,8 +11,12 @@ module Elf
 
     def test_empty_translate
       writer = Elf::ObjectWriter.new(@linker )
-      writer.save "test/zero.o"
+      writer.save StringIO.new
     end
 
+    def test_empty_translate_with_debug
+      writer = Elf::ObjectWriter.new(@linker , debug: true )
+      writer.save StringIO.new
+    end
   end
 end
diff --git a/test/rubyx/macro/test_object_set.rb b/test/rubyx/macro/test_object_set.rb
index 4bf71be2..3f9eadbb 100644
--- a/test/rubyx/macro/test_object_set.rb
+++ b/test/rubyx/macro/test_object_set.rb
@@ -2,7 +2,7 @@ require_relative "helper"
 
 module RubyX
   module Macro
-    class TestObjectGet < MiniTest::Test
+    class TestObjectSet < MiniTest::Test
       include MacroHelper
       def source
         <<GET