minitest testing and code coverage - ruby-on-rails

Question

I use mini-test for testing framework. I use omniauth gem for authentication. I use simplecov for code coverage. I run my tests using "bundle exec rake" or "rake minitest:controllers". I give an example for controllers. When I run rake minitest:controllers, controllers code coverage becomes 100%. But, when I run bundle exec rake, controllers code coverage become 60%.
SessionsController.rb code:
class SessionsController < ApplicationController
def create
auth = request.env["omniauth.auth"]
person=Person.find_by_provider_and_uid(auth.provider,auth.uid) || Person.create_with_omniauth(auth)
redirect_to root_path
end
end
SessionsController_test.rb
require "minitest_helper"
describe SessionsController do
before do
request.env["omniauth.auth"] = OmniAuth.config.mock_auth[:identity]
#person = Fabricate.build(:person)
end
it "should create authentication" do
assert_difference('Person.count') do
post :create, :provider => "identity"
end
assert_redirected_to root_path #person
end
end
I wonder that if I miss one point on writing test. I wait your ideas. Thanks in advance.
EDIT
minitest_helper.rb
require 'simplecov'
Simplecov.start
ENV["RAILS_ENV"] = "test"
require File.expand_path('../../config/environment', __FILE__)
require "minitest/autorun"
require "minitest/rails"
require "minitest/pride"
require 'database_cleaner'
require "minitest/rails/capybara"
require "minitest-mongoid"
DatabaseCleaner[:mongoid].strategy = :truncation
#OmniAuth.config.test_mode = true
OmniAuth.config.add_mock(:identity, {
:uid => '12345'
})
class MiniTest::Spec
before :each do
DatabaseCleaner.start
end
after :each do
DatabaseCleaner.clean
end
end

Answer 1

According to Simplecov's documentation, you just have to add theses lines in top of your test/test_helper.rb:
# test/test_helper.rb
require 'simplecov'
SimpleCov.start
# ...
Also do not forget to install simplecov gem in test group:
# Gemfile
# ...
group :test do
gem 'simplecov'
end
And that's it.
Rails 6: I encountered some issues with Rails 6 and tests paralelization so you may deactivate it in test/test_helper.rb:
# test/test_helper.rb
# ...
class ActiveSupport::TestCase
# ...
# parallelize(workers: 2)
end

Answer 2

It's hard to tell with no more information.
First of all try rake minitest:all and update your question with the result.
Please try following in case the former test did not conclude positively:
namespace :test do
task :coverage do
require 'simplecov'
SimpleCov.start 'rails' # feel free to pass block
Rake::Task["test"].execute
end
end
Let us know and we can edit or update the answer.
Minitest is known to have had some issues with it. I believe it was still work in progress, not sure where they stand now. It is not you, it's minitest. That workaround helped in some cases, maybe it helps you too.