I'm using a helper script to execute rspec tests.
command = "rake spec #{path} #{scope}"
output = `#{command}`
puts output
This works fine, except that I lose all the colors from the rake rspec output. The appropriate ANSI codes do not appear to be contained within the output string.
How can I execute a process so that it returns output which includes the text color?
Kernel.exec() gets me the solution I want (colored rspec output), but it does so by replacing my ruby script process with the rspec process. That means I can't do anything with the output or run anything after the rspec call.
That's acceptable in my particular situation, but less than ideal as a general solution. So I'd like a better answer if available.
RSpec will disable colour if it is not writing to a tty (i.e. the console).
In case of RSpec you can force colouring by rspec --tty or via rake by rake spec SPEC_OPTS=' --tty'.
See also Ruby popen3 and ANSI colour
However this solution is still specific to Rspec. I'd be interested to hear a general one.
Turns out it's possible to run commands in a pseudo terminal via the PTY module in order to preserve a user facing terminal-like behaviour. Credits go to the creator of the tty-command gem (see this issue) who implemented this behaviour in his gem:
require 'tty-command'
cmd = TTY::Command.new(pty: true)
cmd.run('rake', 'rspec')
Keep in mind that using a pseudo terminal may have unwanted side effects, such as certain git commands using a pager which will essentially cause commands to hang. So introducing the functionality might be a breaking change.
If you don't want to replace your ruby process with that command, use Kernel.system() or Kernel.spawn() instead of a Kernel.exec(). Both of them execute your command in a subshell, system waits for the subprocess to finish, spawn returns its pid and you have to wait by yourself using Process.wait pid.
command = "rake spec #{path} #{scope}"
system(command)
or
command = "rake spec #{path} #{scope}"
pid = spawn(command)
# Some other stuff here
Process.wait pid
