Fix some validators when used on model instance

Now that Validator #setup is called from the initializer, we need a
reference to the model's class to be passed in to allow the validators
to continue functioning when used at the instance level.

Closes #14134.

2 files changed, 4 insertions, 2 deletions

diff --git a/activemodel/test/cases/validations_test.rb b/activemodel/test/cases/validations_test.rb
index bee8ece992..cfce8fb8e6 100644
--- a/activemodel/test/cases/validations_test.rb
+++ b/activemodel/test/cases/validations_test.rb
@@ -284,10 +284,11 @@ class ValidationsTest < ActiveModel::TestCase
     auto = Automobile.new
 
     assert          auto.invalid?
-    assert_equal 2, auto.errors.size
+    assert_equal 3, auto.errors.size
 
     auto.make  = 'Toyota'
     auto.model = 'Corolla'
+    auto.approved = '1'
 
     assert auto.valid?
   end
diff --git a/activemodel/test/models/automobile.rb b/activemodel/test/models/automobile.rb
index ece644c40c..4df2fe8b3a 100644
--- a/activemodel/test/models/automobile.rb
+++ b/activemodel/test/models/automobile.rb
@@ -3,10 +3,11 @@ class Automobile
 
   validate :validations
 
-  attr_accessor :make, :model
+  attr_accessor :make, :model, :approved
 
   def validations
     validates_presence_of :make
     validates_length_of   :model, within: 2..10
+    validates_acceptance_of :approved, allow_nil: false
   end
 end