Fix version check to clean up after itself 👮‍♀️

[klappradla]

Hi 👋

first of all: thanx a ton for building an maintaining this gem 💚 It's really helpful 🤗

This PR fixes the check for the mjml version to clean up after itself and not leave a node zombie process lingering around 🧟‍♂️

scenario

We're using Sidekiq to send emails in background jobs and our workers always had some "defunct" node processes lingering around forever - even directly after starting / restarting Sidekiq.

problem

This line in mjml.rb 👇

IO.popen("#{bin} --version").read.include?('mjml-core: 4.0.')

This runs mjml --version as a subprocess. But since the IO object is never closed, the process never gets terminated.

solution

Looking at the docs for IO#popen, the method can also take a block, like so:

IO.popen("#{bin} --version") do |io|
  io.read.include?('mjml-core: 4.0.')
end

☝️ this will do the exact same as the example above, but also clean up after itself, closing the pipe again. The docs on that:

If a block is given, Ruby will run the command as a child connected to Ruby with a pipe. Ruby's end of the pipe will be passed as a parameter to the block. At the end of block, Ruby closes the pipe and sets $?. In this case IO.popen returns the value of the block.

So I think this is the better fit for the version check: no zombie node processes lingering around any more 🎉

[sighmon]

@klappradla You are the actual best. Thanks so much for your fix, and the cutest pull request I've ever had. 🙌🏼

[klappradla]

Thanx for your super fast response @sighmon 🙏

It would be awesome if you could release a patch version soon, so that our operations people have a calm sleep 🛌 and I'm no longer pulling in dependencies straight from Github ✌️

[sighmon]

@klappradla 4.0.2 should be available in Rubygems now. :-)

[klappradla]

🤗 thanx a ton!