diff --git a/.github/workflows/minitest_on_pr_merge.yml b/.github/workflows/minitest_on_pr_merge.yml
index c8d042b..d590a62 100644
--- a/.github/workflows/minitest_on_pr_merge.yml
+++ b/.github/workflows/minitest_on_pr_merge.yml
@@ -23,4 +23,4 @@ jobs:
         ruby-version: ${{ matrix.ruby-version }}
         bundler-cache: true # runs 'bundle install' and caches installed gems automatically
     - name: Run tests
-      run: ruby mini_test_runner.rb
+      run: bundle exec rake
diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index d159de0..dda3c0b 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -35,6 +35,6 @@ jobs:
         ruby-version: ${{ matrix.ruby-version }}
         bundler-cache: true # runs 'bundle install' and caches installed gems automatically
     - name: Run tests
-      run: ruby mini_test_runner.rb
+      run: bundle exec rake
     - name: Coverage Report by octocov (in this pull request)
       uses: k1LoW/octocov-action@v0
diff --git a/Rakefile b/Rakefile
index 932cd61..30c8789 100755
--- a/Rakefile
+++ b/Rakefile
@@ -8,6 +8,7 @@ require 'rspec/core'
 require 'rspec/core/rake_task'
 require 'rdoc/task'
 require 'rake/testtask'
+require 'simplecov'
 
 begin
   Bundler.setup(:default, :development)
@@ -17,18 +18,11 @@ rescue Bundler::BundlerError => e
   exit e.status_code
 end
 
-# rspec
 
-RSpec::Core::RakeTask.new(:spec) do |spec|
-  spec.pattern = FileList['spec/**/*_spec.rb']
-end
-
-RSpec::Core::RakeTask.new(:rcov) do |spec|
-  spec.pattern = 'spec/**/*_spec.rb'
-  spec.rcov = true
-end
+# simplecov
+SimpleCov.start
 
-task :default => :spec
+# RDoc
 
 Rake::RDocTask.new do |rdoc|
   version = File.exist?('VERSION') ? File.read('VERSION') : ""