Add simplecov with codacy integration

Gemfile.lock

@@ -7,6 +7,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     diff-lcs (1.3)
+    docile (1.3.2)
     rake (13.0.1)
     rspec (3.8.0)
       rspec-core (~> 3.8.0)
@@ -21,6 +22,12 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.8.0)
     rspec-support (3.8.0)
+    simplecov (0.19.0)
+      docile (~> 1.1)
+      simplecov-html (~> 0.11)
+    simplecov-cobertura (1.4.0)
+      simplecov (~> 0.8)
+    simplecov-html (0.12.2)
 
 PLATFORMS
   ruby
@@ -30,6 +37,8 @@ DEPENDENCIES
   jsonapi_errors_handler!
   rake
   rspec
+  simplecov
+  simplecov-cobertura
 
 BUNDLED WITH
    2.1.4

jsonapi_errors_handler.gemspec

@@ -2,6 +2,7 @@
 
 lib = File.expand_path('lib', __dir__)
 $LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+
 require 'jsonapi_errors_handler/version'
 
 Gem::Specification.new do |spec|
@@ -43,4 +44,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'bundler'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'rspec'
+  spec.add_development_dependency 'simplecov'
+  spec.add_development_dependency 'simplecov-cobertura'
 end

spec/spec_helper.rb

@@ -1,6 +1,17 @@
 # frozen_string_literal: true
 
 require 'bundler/setup'
+require 'simplecov'
+
+if ENV['CI']
+  require 'simplecov-cobertura'
+  SimpleCov.formatter = SimpleCov::Formatter::CoberturaFormatter
+end
+
+SimpleCov.start do
+  add_filter '/spec/'
+end
+
 require 'jsonapi_errors_handler'
 
 RSpec.configure do |config|