Ruby SimpleCov 0.0 LOC with stand alone .rb code

Question

I am trying to use SimpleCov to gather code coverage information but I can't seem to understand how it works. It always give me 0.0% LOC. Do I need to do something to make it work?

require 'simplecov'
SimpleCov.start
SimpleCov.command_name 'Unit Tests'

def foo
  puts '12345'
end

foo

I see the following output:

$ ruby mytest.rb

12345

Coverage report generated for Unit Tests to /private/tmp/simpletest/coverage. 0.0 / 0.0 LOC (100.0%) covered.

Do I have to use it under rspec or some special environment? Can I not just enable code coverage for arbitrary code?

There is only one method in your question and no test at all. Why would you expect Simplecov not to report 0% test coverage? — spickermann

Casper Casper · Accepted Answer · 2019-12-06T20:23:52

SimpleCov filters the original source file itself out of the coverage report. To make it work standalone like this, you need to put your test code into a separate file:

require 'simplecov'
SimpleCov.start
SimpleCov.command_name 'Unit Tests'

require_relative 'my_code'
foo

Then in my_code.rb:

def foo
  puts '12345'
end

Now you will get a proper report.

Ruby SimpleCov 0.0 LOC with stand alone .rb code

1 Answers