diff --git a/.editorconfig b/.editorconfig
index 6923bce..eb57fc2 100644
--- a/.editorconfig
+++ b/.editorconfig
@@ -8,3 +8,7 @@ trim_trailing_whitespace = true
 [*.yml]
 indent_style = space
 indent_size = 2
+
+[*.md.erb]
+insert_final_newline = false
+trim_trailing_whitespace = false
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 1a9ce59..7e6dd25 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -49,7 +49,9 @@ jobs:
       - name: Install dependencies
         run: bundler install
       - name: Run the test
-        run: bundle exec rake test spec
+        run: bundle exec rake test spec && cat coverage/coverage.md >> $GITHUB_STEP_SUMMARY
+        env:
+          COVERAGE: true
 
   notify:
     runs-on: ubuntu-latest
diff --git a/.gitignore b/.gitignore
index d8d2871..810ff11 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,4 @@
 /.gem_rbs_collection
 /tmp
 /gemfiles/*.lock
+/coverage
diff --git a/.projections.json b/.projections.json
new file mode 100644
index 0000000..a43279c
--- /dev/null
+++ b/.projections.json
@@ -0,0 +1,40 @@
+{
+  "lib/*.rb": {
+      "type": "lib",
+      "alternate": "spec/{}_spec.rb",
+      "related": [
+          "sig/{}.rbs"
+      ]
+  },
+  "test/*_test.rb": {
+      "type": "test",
+      "dispatch": "bundle exec ruby -Itest {file}",
+      "alternate": "lib/{}.rb",
+      "related": [
+          "sig/{}.rbs"
+      ]
+  },
+  "spec/*_spec.rb": {
+      "type": "spec",
+      "dispatch": "bundle exec ruby -Ispec {file}",
+      "alternate": "lib/{}.rb",
+      "related": [
+          "sig/{}.rbs"
+      ]
+  },
+  "sig/*.rbs": {
+      "type": "sig",
+      "alternate": "lib/{}.rb",
+      "related": [
+          "spec/{}_spec.rb",
+          "test/{}_test.rb"
+      ]
+  },
+  "README.md": {
+      "type": "doc"
+  },
+  "*": {
+      "make": "bundle exec rake",
+      "console": "bundle exec irb -rgraft"
+  }
+}
diff --git a/gemfiles/ruby-3.3.gemfile b/gemfiles/ruby-3.3.gemfile
index bbe071f..897dd7a 100644
--- a/gemfiles/ruby-3.3.gemfile
+++ b/gemfiles/ruby-3.3.gemfile
@@ -7,6 +7,7 @@ gem "rake", "~> 13.1.0"
 group :test do
   gem "minitest", "~> 5.22.3"
   gem "minitest-reporters", "~> 1.7.1"
+  gem "simplecov", require: false
 end
 
 group :debug do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 10c3149..7d9094a 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,3 +1,4 @@
 # frozen_string_literal: true
 
+require_relative "spec_helper/simplecov"
 require_relative "spec_helper/minitest/reporter"
diff --git a/spec/spec_helper/simplecov.rb b/spec/spec_helper/simplecov.rb
new file mode 100644
index 0000000..4f6719c
--- /dev/null
+++ b/spec/spec_helper/simplecov.rb
@@ -0,0 +1,24 @@
+if %w[y yes true 1].include? ENV["COVERAGE"]
+  require "simplecov"
+  require "simplecov_json_formatter"
+  require_relative "simplecov/formatters/markdown_formatter"
+
+  SimpleCov.configure do
+    add_filter %r{(?:spec|test|bin)}
+
+    SimpleCov.formatters = [
+      SimpleCov::Formatter::HTMLFormatter,
+      SimpleCov::Formatter::JSONFormatter,
+      SimpleCov::Formatter::MarkdownFormatter
+    ]
+
+    # Ruby 2.5+
+    enable_coverage :branch
+    primary_coverage :branch
+
+    # Ruby 3.2+
+    enable_coverage_for_eval
+  end
+
+  SimpleCov.start
+end
diff --git a/spec/spec_helper/simplecov/formatters/markdown_formatter.rb b/spec/spec_helper/simplecov/formatters/markdown_formatter.rb
new file mode 100644
index 0000000..601a8cb
--- /dev/null
+++ b/spec/spec_helper/simplecov/formatters/markdown_formatter.rb
@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+# Ensure we are using a compatible version of SimpleCov
+major, minor, patch = SimpleCov::VERSION.scan(/\d+/).first(3).map(&:to_i)
+if major < 0 || minor < 9 || patch < 0
+  raise "The version of SimpleCov you are using is too old. " \
+        "Please update with `gem install simplecov` or `bundle update simplecov`"
+end
+
+require "simplecov-html"
+
+module SimpleCov
+  module Formatter
+    class MarkdownFormatter < HTMLFormatter
+      def initialize
+        @branchable_result = SimpleCov.branch_coverage?
+        @templates = {}
+      end
+
+      def format(result)
+        File.open(File.join(output_path, "coverage.md"), "wb") do |file|
+          file.puts template("layout").result(binding)
+        end
+
+        # TODO: disabled til `views/source_file.md.erb` is implemented
+        # result.source_files.each do |source_file|
+        #   path = File.dirname(File.join(output_path, shortened_filename(source_file)))
+        #
+        #   FileUtils.mkdir_p(path)
+        #
+        #   File.open(File.join(output_path, shortened_filename(source_file)) + ".md", "wb") do |file|
+        #     file.puts formatted_source_file(source_file)
+        #   end
+        # end
+
+        puts output_message(result)
+      end
+
+      def output_message(result)
+        str = "Markdown coverage report generated for #{result.command_name} to #{output_path}. #{result.covered_lines} / #{result.total_lines} LOC (#{result.covered_percent.round(2)}%) covered."
+        str += " #{result.covered_branches} / #{result.total_branches} branches (#{result.coverage_statistics[:branch].percent.round(2)}%) covered." if branchable_result?
+        str
+      end
+
+      private
+
+      # Returns the an erb instance for the template of given name
+      def template(name)
+        @templates[name] ||= ERB.new(File.read(File.join(File.dirname(__FILE__), "./views/", "#{name}.md.erb")))
+      end
+
+      def link_to_source_file(source_file)
+        shortened_filename source_file
+      end
+    end
+  end
+end
diff --git a/spec/spec_helper/simplecov/formatters/views/covered_percent.md.erb b/spec/spec_helper/simplecov/formatters/views/covered_percent.md.erb
new file mode 100644
index 0000000..dd208bf
--- /dev/null
+++ b/spec/spec_helper/simplecov/formatters/views/covered_percent.md.erb
@@ -0,0 +1 @@
+<%= percent.round(2) %>%
\ No newline at end of file
diff --git a/spec/spec_helper/simplecov/formatters/views/file_list.md.erb b/spec/spec_helper/simplecov/formatters/views/file_list.md.erb
new file mode 100644
index 0000000..11f665a
--- /dev/null
+++ b/spec/spec_helper/simplecov/formatters/views/file_list.md.erb
@@ -0,0 +1,10 @@
+# All Files ( <%= covered_percent(source_files.covered_percent) %> covered at <%= source_files.covered_strength.round(2) %> ) hits / line
+
+**<%= source_files.length %>** files in total.  
+**<%= source_files.lines_of_code %>** relevant lines, **<%= source_files.covered_lines %>** lines covered and **<%= source_files.missed_lines %>** lines missed. (<%= covered_percent(source_files.covered_percent) %>)<% if branchable_result? %>  
+**<%= source_files.total_branches %>** total branches, **<%= source_files.covered_branches %>** branches covered and **<%= source_files.missed_branches %>** branches missed. (<%= covered_percent(source_files.branch_covered_percent) %>)<% end %>
+
+| File | % covered | Lines | Relevant Lines | Lines covered | Lines missed | Avg. Hits / Line | <% if branchable_result? %> Branch Coverage | Branches | Covered branches | Missed branches | <% end %>
+| ---- | --------: | ----: | -------------: | ------------: | -----------: | ---------------: | <% if branchable_result? %> --------------: | -------: | ---------------: | --------------: | <% end %>
+<% source_files.each do |source_file| %>| <%= link_to_source_file(source_file) %> | <%= sprintf("%.2f", source_file.covered_percent.round(2)) %> % | <%= source_file.lines.count %> | <%= source_file.covered_lines.count + source_file.missed_lines.count %> | <%= source_file.covered_lines.count %> | <%= source_file.missed_lines.count %> | <%= sprintf("%.2f", source_file.covered_strength.round(2)) %> |<% if branchable_result? %> <%= sprintf("%.2f", source_file.branches_coverage_percent.round(2)) %> % | <%= source_file.total_branches.count %> | <%= source_file.covered_branches.count %> | <%= source_file.missed_branches.count %> |<% end %>
+<% end %>
diff --git a/spec/spec_helper/simplecov/formatters/views/layout.md.erb b/spec/spec_helper/simplecov/formatters/views/layout.md.erb
new file mode 100644
index 0000000..cd3f2f1
--- /dev/null
+++ b/spec/spec_helper/simplecov/formatters/views/layout.md.erb
@@ -0,0 +1,6 @@
+<!-- Generated <%= Time.now %> -->
+<%= formatted_file_list("All Files", result.source_files) %>
+
+<% result.groups.each do |name, files| %>
+<%= formatted_file_list(name, files) %>
+<% end %>
\ No newline at end of file
diff --git a/spec/spec_helper/simplecov/formatters/views/source_file.md.erb b/spec/spec_helper/simplecov/formatters/views/source_file.md.erb
new file mode 100644
index 0000000..c5cefd3
--- /dev/null
+++ b/spec/spec_helper/simplecov/formatters/views/source_file.md.erb
@@ -0,0 +1 @@
+<%= shortened_filename source_file %>
\ No newline at end of file