Safety net for running unit specs

spec/spec_helper.rb

@@ -13,7 +13,7 @@ Bundler.require
 
 require 'rspec-spies'
 
-Dir[File.dirname(__FILE__) + "/spec/support/**/*.rb"].each { |f| require f }
+Dir[File.dirname(__FILE__) + "/support/**/*.rb"].each { |f| require f }
 
 RSpec.configure do |config|
   config.treat_symbols_as_metadata_keys_with_true_values = true

spec/support/unit_example_group.rb

@@ -0,0 +1,24 @@
+module UnitExampleGroup
+  def self.included(base)
+    base.metadata[:type] = :unit
+    base.before do
+      Object.any_instance.stub(:system) { |*args, &block|
+        UnitExampleGroup.prevent_system_calls(*args, &block)
+      }
+      Vagrant::Util::Subprocess.stub(:execute) { |*args, &block|
+        UnitExampleGroup.prevent_system_calls(*args, &block)
+      }
+    end
+  end
+
+  def self.prevent_system_calls(*args, &block)
+    args.pop if args.last.is_a?(Hash)
+
+    raise <<-MSG
+Somehow your code under test is trying to execute a command on your system,
+please stub it out or move your spec code to an acceptance spec.
+
+Command: "#{args.join(' ')}"
+    MSG
+  end
+end

spec/unit_helper.rb

@@ -2,4 +2,8 @@ require 'spec_helper'
 
 RSpec.configure do |config|
   config.include RSpec::Fire
+
+  config.include UnitExampleGroup, :type => :unit, :example_group => {
+    :file_path => /\bspec\/unit\//
+  }
 end