Convert 14 more message specs to lightweight_spec_helper

Add errors_on helper and VCAP::CloudController::Config stub to
lightweight_spec_helper to enable more message spec conversions.

Converted specs:
- deployment_update_message_spec.rb
- domain_create_message_spec.rb
- droplet_copy_message_spec.rb
- droplet_create_message_spec.rb
- droplet_update_message_spec.rb
- isolation_segment_create_message_spec.rb
- isolation_segment_update_message_spec.rb
- metadata_base_message_spec.rb
- organization_quotas_list_message_spec.rb
- service_brokers_list_message_spec.rb
- space_quotas_list_message_spec.rb
- update_environment_variables_message_spec.rb
- users_list_message_spec.rb
- validators/url_validator_spec.rb

Now 70 message specs use lightweight_spec_helper (vs 82 on spec_helper).

Author: johha

spec/lightweight_spec_helper.rb

@@ -2,10 +2,21 @@
 $LOAD_PATH.push(File.expand_path(File.join(__dir__, '..', 'lib')))
 
 require 'active_support/all'
+require 'active_model'
 require 'pry'
 # So that specs using this helper don't fail with undefined constant error
 module VCAP
   module CloudController
+    # Minimal Config stub for message validation specs
+    class Config
+      def self.config
+        @config ||= new
+      end
+
+      def get(*_keys)
+        nil
+      end
+    end
   end
 end
 
@@ -34,3 +45,19 @@ def get(key)
 RSpec.configure do |rspec_config|
   rspec_config.expose_dsl_globally = false
 end
+
+# errors_on helper from rspec-collection_matchers gem
+# Enables: expect(message.errors_on(:attribute)).to include("error message")
+# This extension is added when ActiveModel::Validations is loaded
+if defined?(ActiveModel::Validations)
+  module ::ActiveModel::Validations
+    def errors_on(attribute, options={})
+      valid_args = [options[:context]].compact
+      valid?(*valid_args)
+
+      [errors[attribute]].flatten.compact
+    end
+
+    alias_method :error_on, :errors_on
+  end
+end

spec/unit/messages/deployment_update_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/deployment_update_message'
 
 module VCAP::CloudController

spec/unit/messages/domain_create_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/domain_create_message'
 
 module VCAP::CloudController

spec/unit/messages/droplet_copy_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/droplet_copy_message'
 
 module VCAP::CloudController

spec/unit/messages/droplet_create_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/droplet_create_message'
 
 module VCAP::CloudController

spec/unit/messages/droplet_update_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/droplet_update_message'
 
 module VCAP::CloudController

spec/unit/messages/isolation_segment_create_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/isolation_segment_create_message'
 
 module VCAP::CloudController

spec/unit/messages/isolation_segment_update_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/isolation_segment_update_message'
 
 module VCAP::CloudController

spec/unit/messages/metadata_base_message_spec.rb

@@ -1,4 +1,4 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
 require 'messages/metadata_base_message'
 
 module VCAP::CloudController

spec/unit/messages/organization_quotas_list_message_spec.rb

@@ -1,4 +1,5 @@
-require 'spec_helper'
+require 'lightweight_spec_helper'
+require 'messages/organization_quotas_list_message'
 
 module VCAP::CloudController
   RSpec.describe OrganizationQuotasListMessage do