Fix codecov/simplecov configurations

.simplecov

@@ -1,12 +1,32 @@
 # frozen_string_literal: true
 
-SimpleCov.start do
-  root ENV.fetch("ENGINE_ROOT", nil)
+if ENV["SIMPLECOV"]
+  SimpleCov.start do
+    # `ENGINE_ROOT` holds the name of the engine we are testing.
+    # This brings us to the main Decidim folder.
+    root ENV.fetch("ENGINE_ROOT", nil)
 
-  add_filter "lib/decidim/apiauth/version.rb"
-  add_filter "/spec"
-end
+    # We make sure we track all Ruby files, to avoid skipping unrequired files
+    # We need to include the `../` section, otherwise it only tracks files from the
+    # `ENGINE_ROOT` folder for some reason.
+    track_files "**/*.rb"
+
+    # We ignore some of the files because they are never tested
+    add_filter "/config/"
+    add_filter "/db/"
+    add_filter "/vendor/"
+    add_filter "/spec/"
+    add_filter "/test/"
+    add_filter %r{^/lib/decidim/[^/]*/engine.rb}
+    add_filter %r{^/lib/decidim/[^/]*/admin_engine.rb}
+    add_filter %r{^/lib/decidim/[^/]*/component.rb}
+    add_filter %r{^/lib/decidim/[^/]*/participatory_space.rb}
+  end
 
-SimpleCov.command_name ENV.fetch("COMMAND_NAME", nil) || File.basename(Dir.pwd)
+  SimpleCov.merge_timeout 1800
 
-SimpleCov.merge_timeout 1800
+  if ENV["CI"]
+    require "simplecov-cobertura"
+    SimpleCov.formatter = SimpleCov::Formatter::CoberturaFormatter
+  end
+end

Gemfile

@@ -34,7 +34,3 @@ group :development do
   gem "spring-watcher-listen", "~> 2.0"
   gem "web-console", "~> 3.5"
 end
-
-group :test do
-  gem "codecov", require: false
-end

Gemfile.lock

@@ -135,8 +135,6 @@ GEM
     chef-utils (18.2.7)
       concurrent-ruby
     childprocess (4.1.0)
-    codecov (0.6.0)
-      simplecov (>= 0.15, < 0.22)
     coercible (1.0.0)
       descendants_tracker (~> 0.0.1)
     coffee-rails (5.0.0)
@@ -820,7 +818,6 @@ PLATFORMS
 DEPENDENCIES
   bootsnap (~> 1.4)
   byebug (~> 11.0)
-  codecov
   decidim (~> 0.27.0)
   decidim-apiauth!
   decidim-dev (~> 0.27.0)

spec/spec_helper.rb

@@ -2,13 +2,6 @@
 
 require "decidim/dev"
 
-require "simplecov"
-SimpleCov.start "rails"
-if ENV["CODECOV"]
-  require "codecov"
-  SimpleCov.formatter = SimpleCov::Formatter::Codecov
-end
-
 ENV["ENGINE_ROOT"] = File.dirname(__dir__)
 
 Decidim::Dev.dummy_app_path =