Getting NameError: undefined method `start' for class `#<Class:0x000056251f39f6a8>'

Question

Added below configuration in spec_helper.rb on top of file.

require 'simplecov'
SimpleCov.start 'rails'

I am trying to generate the specs coverage report using SimpleCov. Installed simplecov gem too.

Rails version is 5. Still not able to generate coverage folder.