test runner: require all Gems from the main program

tests/run.rb

@@ -1,6 +1,8 @@
 #!/usr/bin/env ruby
 
+require "digest/md5"
 require "json"
+require "json_schema"
 require "pp"
 require "tempfile"
 

tests/test.d/simple_test.rb

@@ -334,8 +334,6 @@ class SimpleTest
   def json_schema_identification
     return @@json_schema_identification if @@json_schema_identification
 
-    require "json_schema"
-
     json_store = JsonSchema::DocumentStore.new
     parser     = JsonSchema::Parser.new
     expander   = JsonSchema::ReferenceExpander.new

tests/test.d/util.rb

@@ -1,5 +1,3 @@
-require 'digest/md5'
-
 $message_mutex = Mutex.new
 def show_message message
   $message_mutex.lock