diff --git a/.gitignore b/.gitignore
index 6580b98..bffc7ad 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 *.gem
 .Trash*
 *.log
+coverage
diff --git a/Gemfile.lock b/Gemfile.lock
index 09ebfc9..488adff 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -49,6 +49,7 @@ GEM
     debug (1.11.1)
       irb (~> 1.10)
       reline (>= 0.3.8)
+    docile (1.4.1)
     drb (2.2.3)
     erb (6.0.1)
     etc (1.4.6)
@@ -165,6 +166,12 @@ GEM
     ruby-progressbar (1.13.0)
     securerandom (0.4.1)
     shellany (0.0.1)
+    simplecov (0.22.0)
+      docile (~> 1.1)
+      simplecov-html (~> 0.11)
+      simplecov_json_formatter (~> 0.1)
+    simplecov-html (0.13.2)
+    simplecov_json_formatter (0.1.4)
     sqlite3 (2.9.0-aarch64-linux-musl)
     stringio (3.2.0)
     sync (0.5.0)
@@ -202,6 +209,7 @@ DEPENDENCIES
   rubocop-rake
   rubocop-rspec
   ruby_language_server!
+  simplecov
 
 CHECKSUMS
   activemodel (8.1.1)
@@ -218,6 +226,7 @@ CHECKSUMS
   connection_pool (3.0.2)
   date (3.5.1)
   debug (1.11.1)
+  docile (1.4.1)
   drb (2.2.3)
   erb (6.0.1)
   etc (1.4.6)
@@ -271,6 +280,9 @@ CHECKSUMS
   ruby_language_server (0.4.2)
   securerandom (0.4.1)
   shellany (0.0.1)
+  simplecov (0.22.0)
+  simplecov-html (0.13.2)
+  simplecov_json_formatter (0.1.4)
   sqlite3 (2.9.0-aarch64-linux-musl)
   stringio (3.2.0)
   sync (0.5.0)
diff --git a/Makefile b/Makefile
index 0a2c2d4..d8cf9e7 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,9 @@ console: image
 test: image
 	./bin/run_in_shell "bundle exec rake test && bundle exec rubocop"
 
+coverage: image
+	./bin/run_in_shell "COVERAGE=true bundle exec rake test"
+
 shell: image
 	./bin/run_in_shell sh
 
diff --git a/ruby_language_server.gemspec b/ruby_language_server.gemspec
index 9f5c62d..a43d72a 100644
--- a/ruby_language_server.gemspec
+++ b/ruby_language_server.gemspec
@@ -59,5 +59,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'rubocop-performance' # Linter - no longer needed - use additional gems?
   spec.add_development_dependency 'rubocop-rake'
   spec.add_development_dependency 'rubocop-rspec'       # Linter - no longer needed - use additional gems?
+  spec.add_development_dependency 'simplecov'
   spec.metadata['rubygems_mfa_required'] = 'true'
 end
diff --git a/spec/test_helper.rb b/spec/test_helper.rb
index 634f87c..d881380 100644
--- a/spec/test_helper.rb
+++ b/spec/test_helper.rb
@@ -1,5 +1,13 @@
 # frozen_string_literal: true
 
+if ENV['COVERAGE']
+  require 'simplecov'
+  SimpleCov.start do
+    add_filter '/spec/'
+    add_filter '/vendor/'
+  end
+end
+
 require 'debug'
 require 'ostruct'
 require_relative '../lib/ruby_language_server'