rename test files with test_prefix

update rakefile

rakefile

@@ -3,7 +3,7 @@ require "rake/testtask"
 HERE = __dir__
 
 Rake::TestTask.new do |t|
-  t.pattern = "test/**/*_test.rb"
+  t.pattern = "test/test_*.rb"
 end
 
 task default: :test

test/minitest_helper.rb

@@ -1,6 +1,5 @@
 require "minitest/autorun"
-
+require "voicemeeter"
-require_relative "../lib/voicemeeter"
 
 class Test
   class << self

test/test_error.rb

@@ -1,5 +1,5 @@
 require_relative "minitest_helper"
-require_relative "../lib/voicemeeter"
+require "voicemeeter"
 
 class CAPIErrorTest < Minitest::Test
   def test_it_raises_an_unknown_parameter_error