Use new Undercover formatter for :nocov: support

.rubocop_styleguide.yml

@@ -16,6 +16,7 @@ AllCops:
     - node_modules/**/*
     # Excluding: inadequate Naming/FileName rule rejects GemFile name with camelcase
     - engines/web/Gemfile
+    - .undercover
 
 Bundler/DuplicatedGem:
   Enabled: false

.undercover

@@ -1,5 +1,4 @@
 #!/bin/env ruby
 # frozen_string_literal: true
 
--l coverage/lcov/openfoodnetwork.lcov
--c master
+-c master

Gemfile

@@ -172,8 +172,6 @@ end
 group :test do
   gem 'pdf-reader'
   gem 'rails-controller-testing'
-  gem 'simplecov', require: false
-  gem 'simplecov-lcov', require: false
   gem 'undercover', require: false
   gem 'vcr', require: false
   gem 'webmock', require: false

Gemfile.lock

@@ -746,7 +746,6 @@ GEM
       simplecov-html (~> 0.11)
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
-    simplecov-lcov (0.8.0)
     simplecov_json_formatter (0.1.4)
     spreadsheet_architect (5.0.0)
       caxlsx (>= 3.3.0, < 4)
@@ -991,8 +990,6 @@ DEPENDENCIES
   shoulda-matchers
   sidekiq
   sidekiq-scheduler
-  simplecov
-  simplecov-lcov
   spreadsheet_architect
   spring
   spring-commands-rspec

lib/tasks/simplecov.rake

@@ -5,7 +5,7 @@ namespace :simplecov do
   task :collate_results, # rubocop:disable Rails/RakeEnvironment doesn't need the full env
        [:path_to_results, :coverage_dir] do |_t, args|
     require "simplecov"
-    require "simplecov-lcov"
+    require "undercover/simplecov_formatter"
 
     path_to_results = args[:path_to_results].presence || "tmp/simplecov"
     output_path = args[:coverage_dir].presence || "coverage"
@@ -15,9 +15,8 @@ namespace :simplecov do
       coverage_dir(output_path)
     end
 
-    SimpleCov::Formatter::LcovFormatter.config.report_with_single_file = true
     SimpleCov.collate Dir[File.join(path_to_results, "**", ".resultset.json")], "rails" do
-      formatter(SimpleCov::Formatter::LcovFormatter)
+      formatter(SimpleCov::Formatter::Undercover)
       coverage_dir(output_path)
     end
   end

spec/lib/tasks/simplecov_spec.rb

@@ -26,6 +26,10 @@ RSpec.describe "simplecov.rake" do
 
             and change { File.exist?(File.join(output_dir, "index.html")) }.
             from(false).
+            to(true).
+
+            and change { File.exist?(File.join(output_dir, "coverage.json")) }.
+            from(false).
             to(true)
         end
       end