1 files changed, 25 insertions, 0 deletions
diff --git a/activerecord/test/cases/associations/has_one_associations_test.rb b/activerecord/test/cases/associations/has_one_associations_test.rb
index 1f78c73f71..a4650ccdf2 100644
--- a/activerecord/test/cases/associations/has_one_associations_test.rb
+++ b/activerecord/test/cases/associations/has_one_associations_test.rb
@@ -22,6 +22,13 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     assert_equal Account.find(1).credit_limit, companies(:first_firm).account.credit_limit
   end
 
+  def test_has_one_does_not_use_order_by
+    ActiveRecord::SQLCounter.clear_log
+    companies(:first_firm).account
+  ensure
+    assert ActiveRecord::SQLCounter.log_all.all? { |sql| /order by/i !~ sql }, 'ORDER BY was used in the query'
+  end
+
   def test_has_one_cache_nils
     firm = companies(:another_firm)
     assert_queries(1) { assert_nil firm.account }
@@ -549,4 +556,22 @@ class HasOneAssociationsTest < ActiveRecord::TestCase
     assert_not_nil author.post
     assert_equal author.post, post
   end
+
+  def test_has_one_relationship_cannot_have_a_counter_cache
+    assert_raise(ArgumentError) do
+      Class.new(ActiveRecord::Base) do
+        has_one :thing, counter_cache: true
+      end
+    end
+  end
+
+  test 'dangerous association name raises ArgumentError' do
+    [:errors, 'errors', :save, 'save'].each do |name|
+      assert_raises(ArgumentError, "Association #{name} should not be allowed") do
+        Class.new(ActiveRecord::Base) do
+          has_one name
+        end
+      end
+    end
+  end
 end