Add simplecov

Add simplecov reports to know about the test coverage

Gemfile.lock

@@ -17,6 +17,7 @@ GEM
     ast (2.4.2)
     concurrent-ruby (1.1.8)
     diff-lcs (1.4.4)
+    docile (1.4.0)
     i18n (1.8.10)
       concurrent-ruby (~> 1.0)
     liquid (5.0.1)
@@ -53,6 +54,12 @@ GEM
     rubocop-ast (1.7.0)
       parser (>= 3.0.1.1)
     ruby-progressbar (1.11.0)
+    simplecov (0.21.2)
+      docile (~> 1.1)
+      simplecov-html (~> 0.11)
+      simplecov_json_formatter (~> 0.1)
+    simplecov-html (0.12.3)
+    simplecov_json_formatter (0.1.3)
     tzinfo (2.0.4)
       concurrent-ruby (~> 1.0)
     unicode-display_width (1.7.0)
@@ -66,6 +73,7 @@ DEPENDENCIES
   rake (~> 13.0)
   rspec (~> 3.0)
   rubocop (~> 0.80)
+  simplecov (~> 0.21)
 
 BUNDLED WITH
    2.2.2

liquid_dynamic_context.gemspec

@@ -36,6 +36,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rake", "~> 13.0"
   spec.add_development_dependency "rspec", "~> 3.0"
   spec.add_development_dependency "rubocop", "~> 0.80"
+  spec.add_development_dependency "simplecov", "~> 0.21"
 
   # For more information and examples about making a new gem, checkout our
   # guide at: https://bundler.io/guides/creating_gem.html

spec/spec_helper.rb

@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
+require "simplecov"
+SimpleCov.start
+
 require "liquid_dynamic_context"
 
 RSpec.configure do |config|