gems:
gem 'simplecov', '~> 0.16'
gem 'simplecov-console'
gem 'minitest-reporters'

test_helper.rb

require 'simplecov'
require 'simplecov-console'
require "minitest/reporters"
require 'webmock/minitest'

class Minitest::Reporters::SpecReporter
  def record_print_status(test)
    print_colored_status(test)
    print(" (%.2fs)" % test.time) unless test.time.nil?

    test_name = test.name.gsub(/^test_: /, 'test:')
    print pad_test(test_name)
    puts
  end
end

# For tests performance tuning:
#Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
Minitest::Reporters.use! Minitest::Reporters::ProgressReporter.new

SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter.new([
  SimpleCov::Formatter::HTMLFormatter,
  SimpleCov::Formatter::Console,
])