Set `GEMNAME` on bintest

test/assert.rb

@@ -22,9 +22,7 @@ def assertion_string(err, str, iso=nil, e=nil, bt=nil)
   msg = "#{err}#{str}"
   msg += " [#{iso}]" if iso && !iso.empty?
   msg += " => #{e}" if e && !e.to_s.empty?
-  if Object.const_defined?(:GEMNAME)
-    msg += " (#{GEMNAME == 'mruby-test' ? 'core' : "mrbgems: #{GEMNAME}"})"
-  end
+  msg += " (#{GEMNAME == 'mruby-test' ? 'core' : "mrbgems: #{GEMNAME}"})"
   if $mrbtest_assert && $mrbtest_assert.size > 0
     $mrbtest_assert.each do |idx, assert_msg, diff|
       msg += "\n - Assertion[#{idx}] Failed: #{assert_msg}\n#{diff}"

test/bintest.rb

 $:.unshift File.dirname(File.dirname(File.expand_path(__FILE__)))
 require 'test/assert.rb'
 
+GEMNAME = ""
+
 def cmd(s)
   case RbConfig::CONFIG['host_os']
   when /mswin(?!ce)|mingw|bccwin/
@@ -30,6 +32,7 @@ ARGV.each do |gem|
   end
 
   Dir["#{gem}/bintest/**/*.rb"].each do |file|
+    GEMNAME.replace(File.basename(gem))
     load file
   end
 end