Move writing unknown column exception to null attribute

Making this change revealed several subtle bugs related to models with
no primary key, and anonymous classes. These have been fixed as well,
with regression tests added.

1 files changed, 10 insertions, 2 deletions

diff --git a/activerecord/test/cases/primary_keys_test.rb b/activerecord/test/cases/primary_keys_test.rb
index f43483d291..b04df7ce43 100644
--- a/activerecord/test/cases/primary_keys_test.rb
+++ b/activerecord/test/cases/primary_keys_test.rb
@@ -134,14 +134,22 @@ class PrimaryKeysTest < ActiveRecord::TestCase
   end
 
   def test_primary_key_returns_value_if_it_exists
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = 'developers'
+    end
+
     if ActiveRecord::Base.connection.supports_primary_key?
-      assert_equal 'id', ActiveRecord::Base.connection.primary_key('developers')
+      assert_equal 'id', klass.primary_key
     end
   end
 
   def test_primary_key_returns_nil_if_it_does_not_exist
+    klass = Class.new(ActiveRecord::Base) do
+      self.table_name = 'developers_projects'
+    end
+
     if ActiveRecord::Base.connection.supports_primary_key?
-      assert_nil ActiveRecord::Base.connection.primary_key('developers_projects')
+      assert_nil klass.primary_key
     end
   end