How to check the compatible Ruby versions for a gem

Question

How do I find out if a particular gem is compatible with a certain Ruby version or not?

I want to upgrade the Ruby version of an application I am working on, But I did n

Answer 1

I found something more interesting on Rubygems.org, that serves as an API that renders a JSON/XML response about the gem.

Often it is mentioned in Rubygems.org but not in the gemspec file about the Ruby version compatibility.

This is a one-off way to fetch it:

curl https://rubygems.org/api/v2/rubygems/activerecord/versions/4.2.7.1.json

{
  "name": "activerecord",
  "downloads": 163190934,
  "version": "4.2.7.1",
  "version_downloads": 6061660,
  "platform": "ruby",
  "authors": "David Heinemeier Hansson",
  "info": "Databases on Rails. Build a persistent domain model by mapping database tables to Ruby classes. Strong conventions for associations, validations, aggregations, migrations, and testing come baked-in.",
  "licenses": [
    "MIT"
  ],
  "metadata": {},
  "sha": "923a64e2ebb9c4529761bf65ed37601a7000af2f3b18f12ea00e9f9ba2a168d2",
  "project_uri": "https://rubygems.org/gems/activerecord",
  "gem_uri": "https://rubygems.org/gems/activerecord-4.2.7.1.gem",
  "homepage_uri": "http://rubyonrails.org",
  "wiki_uri": null,
  "documentation_uri": "http://www.rubydoc.info/gems/activerecord/4.2.7.1",
  "mailing_list_uri": null,
  "source_code_uri": null,
  "bug_tracker_uri": null,
  "changelog_uri": null,
  "dependencies": {
    "development": [],
    "runtime": [
      {
        "name": "activemodel",
        "requirements": "= 4.2.7.1"
      },
      {
        "name": "activesupport",
        "requirements": "= 4.2.7.1"
      },
      {
        "name": "arel",
        "requirements": "~> 6.0"
      }
    ]
  },
  "built_at": "2016-08-10T00:00:00.000Z",
  "created_at": "2016-08-11T17:33:45.486Z",
  "description": "Databases on Rails. Build a persistent domain model by mapping database tables to Ruby classes. Strong conventions for associations, validations, aggregations, migrations, and testing come baked-in.",
  "downloads_count": 6061660,
  "number": "4.2.7.1",
  "summary": "Object-relational mapper framework (part of Rails).",
  "rubygems_version": ">= 0",
  "ruby_version": ">= 1.9.3",
  "prerelease": false,
  "requirements": []
}

And extract ruby_version.

See API documentation for more information.