chore(test): add and configure SimpleCov for test coverage measurement and reporting

Author: patrickgramatowski

.gitignore

@@ -9,3 +9,6 @@
 
 # rspec failure tracking
 .rspec_status
+
+.DS_Store
+coverage

Gemfile

@@ -10,3 +10,5 @@ gem "rake", "~> 13.0"
 gem "rspec", "~> 3.0"
 
 gem "rubocop", "~> 1.21"
+
+gem "simplecov", "~> 0.22", require: false, group: :test

Gemfile.lock

@@ -12,6 +12,7 @@ GEM
     ast (2.4.3)
     diff-lcs (1.6.2)
     digest (3.2.0)
+    docile (1.4.0)
     json (2.12.2)
     language_server-protocol (3.17.0.5)
     lint_roller (1.1.0)
@@ -52,6 +53,12 @@ GEM
       parser (>= 3.3.7.2)
       prism (~> 1.4)
     ruby-progressbar (1.13.0)
+    simplecov (0.22.0)
+      docile (~> 1.1)
+      simplecov-html (~> 0.11)
+      simplecov_json_formatter (~> 0.1)
+    simplecov-html (0.12.3)
+    simplecov_json_formatter (0.1.4)
     thor (1.3.2)
     unicode-display_width (3.1.4)
       unicode-emoji (~> 4.0, >= 4.0.4)
@@ -67,6 +74,7 @@ DEPENDENCIES
   rake (~> 13.0)
   rspec (~> 3.0)
   rubocop (~> 1.21)
+  simplecov (~> 0.22)
 
 BUNDLED WITH
    2.5.17

spec/spec_helper.rb

@@ -2,9 +2,12 @@
 
 require "doc_guard"
 require "open3"
+require "simplecov"
 require "tempfile"
 require "tmpdir"
 
+SimpleCov.start
+
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
   config.example_status_persistence_file_path = ".rspec_status"