Debugging Ruby locally in VSCode using ruby-debug and native breakpoints

27 September, 2019 - 2 min read

This is one of the biggest pain points I've had developing with ruby on rails and rspec, and I could never get the ruby extension by rebornix to debug properly with breakpoints. Using the ruby-debug extension by the developer of the Solargraph extension, you are now able to debug rspec and ruby scripts locally!

In the extensions marketplace, search "ruby-debug" and install globally. You may need to reload your workspace afterwards.

You'll need to add readapt to your project's gemfile and bundle install.

group :development do
  # gems...
  gem 'readapt' # Debugging with vscode ruby-debug extension
  # gems...
end

Then add the appropriate configuration either to your global settings.json:

{
"launch": {
  "version": "0.2.0",
  "configurations": [
      {
      "type": "ruby-debug",
      "request": "launch",
      "name": "Ruby",
      "program": "${file}",
      "programArgs": [],
      "useBundler": false
    },
    {
      "type": "ruby-debug",
      "request": "launch",
      "name": "RSpec LocalFile",
      "program": "rspec",
      "programArgs": ["${relativeFile}"],
      "useBundler": true
    },
    {
      "type": "ruby-debug",
      "request": "launch",
      "name": "RSpec Selected Line",
      "program": "rspec",
      "programArgs": ["${relativeFile}:${lineNumber}"],
      "useBundler": true
    }
  ]
}

or your workspace/.vscode/launch.json file

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "ruby-debug",
      "request": "launch",
      "name": "Ruby",
      "program": "${file}",
      "programArgs": [],
      "useBundler": false
    },
    {
      "type": "ruby-debug",
      "request": "launch",
      "name": "RSpec LocalFile",
      "program": "rspec",
      "programArgs": ["${relativeFile}"],
      "useBundler": true
    },
    {
      "type": "ruby-debug",
      "request": "launch",
      "name": "RSpec Selected Line",
      "program": "rspec",
      "programArgs": ["${relativeFile}:${lineNumber}"],
      "useBundler": true
    }
  ]
}

Open an rspec test or plain ol' ruby file, and go to the debug tab. Select the option you want to run when you press F5.

Put a breakpoint in your file and press F5 or click the green arrow shown above to run the test.

Use the debug window at the bottom of your window to debug!