Reload schema after ignored_columns reassignment

reload column_names after ignored_columns assignment

code review: remove unnecessary setup and move up reload_schema_from_cache

activerecord/lib/active_record/model_schema.rb

@@ -288,6 +288,7 @@ module ActiveRecord
       # Sets the columns names the model should ignore. Ignored columns won't have attribute
       # accessors defined, and won't be referenced in SQL queries.
       def ignored_columns=(columns)
+        reload_schema_from_cache
         @ignored_columns = columns.map(&:to_s)
       end
 

activerecord/test/cases/base_test.rb

@@ -1503,6 +1503,10 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal "Developer: name", loaded_developer.name
   end
 
+  test "when assigning new ignored columns it invalidates cache for column names" do
+    assert_not_includes ColumnNamesCachedDeveloper.column_names, "name"
+  end
+
   test "ignored columns not included in SELECT" do
     query = Developer.all.to_sql.downcase
 

activerecord/test/models/developer.rb

@@ -303,3 +303,8 @@ class AttributedDeveloper < ActiveRecord::Base
 
   self.ignored_columns += ["name"]
 end
+
+class ColumnNamesCachedDeveloper < ActiveRecord::Base
+  self.table_name = "developers"
+  self.ignored_columns += ["name"] if column_names.include?("name")
+end