Drop three blank? duplicates in favor of ActiveSupport Object#blank?

Configuration, UserProvisioner, and Presets::Zitadel each shipped
their own private 'def blank?(value); value.nil? || value.to_s.strip.empty?; end'
helper — same body, three copies. Rails >= 7.2 is a hard dependency
of this gem, so ActiveSupport is always present in the host app; we
only need to opt in to the core_ext at the gem entry point for unit
specs that don't boot Rails and we get the standard Object#blank?
behaviour everywhere else for free.

Net -13 lines and a removal of subtle behaviour drift (the old
helper treated false and 0 differently than the AS version would;
nothing in the current call sites cared about either, but having
only one definition means future call sites don't have to either).

Author: Fivell

lib/activeadmin-oidc.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require "logger"
+require "active_support/core_ext/object/blank"
 require "activeadmin/oidc/version"
 
 # `omniauth-rails_csrf_protection` registers a Railtie that replaces

lib/activeadmin/oidc/configuration.rb

@@ -56,21 +56,15 @@ def preset(name)
       end
 
       def validate!
-        raise ConfigurationError, "issuer is required"    if blank?(issuer)
-        raise ConfigurationError, "client_id is required" if blank?(client_id)
+        raise ConfigurationError, "issuer is required"    if issuer.blank?
+        raise ConfigurationError, "client_id is required" if client_id.blank?
         raise ConfigurationError, "on_login is required"  if on_login.nil?
         unless on_login.respond_to?(:call)
           raise ConfigurationError, "on_login must be callable (respond to #call)"
         end
 
         true
       end
-
-      private
-
-      def blank?(value)
-        value.nil? || value.to_s.strip.empty?
-      end
     end
   end
 end

lib/activeadmin/oidc/presets/zitadel.rb

@@ -8,13 +8,9 @@ module Zitadel
 
         def self.apply(config)
           config.scope = DEFAULT_SCOPE if config.scope == Configuration::DEFAULT_SCOPE
-          config.pkce  = true if blank?(config.client_secret) && config.instance_variable_get(:@pkce_override).nil?
+          config.pkce  = true if config.client_secret.blank? && config.instance_variable_get(:@pkce_override).nil?
           config
         end
-
-        def self.blank?(value)
-          value.nil? || value.to_s.strip.empty?
-        end
       end
     end
   end

lib/activeadmin/oidc/user_provisioner.rb

@@ -58,12 +58,12 @@ def admin_user_class
       end
 
       def validate_claims!
-        if blank?(@claims["sub"])
+        if @claims["sub"].blank?
           raise ProvisioningError, "OIDC id_token is missing a sub claim"
         end
 
         claim_key = @config.identity_claim.to_s
-        if blank?(@claims[claim_key])
+        if @claims[claim_key].blank?
           raise ProvisioningError,
                 "OIDC id_token is missing identity claim #{claim_key.inspect}"
         end
@@ -129,10 +129,6 @@ def invoke_on_login(admin_user)
       def denial_message
         @config.access_denied_message
       end
-
-      def blank?(value)
-        value.nil? || value.to_s.strip.empty?
-      end
     end
   end
 end