Deprecate assert_valid

actionpack/lib/action_controller/assertions/model_assertions.rb

@@ -11,6 +11,7 @@ module ModelAssertions
       #   assert_valid(model)
       #
       def assert_valid(record)
+        ::ActiveSupport::Deprecation.warn("assert_valid is deprecated. Use assert record.valid? instead", caller)
         clean_backtrace do
           assert record.valid?, record.errors.full_messages.join("\n")
         end

actionpack/test/controller/action_pack_assertions_test.rb

@@ -461,14 +461,14 @@ def test_redirected_to_with_nested_controller
 
   def test_assert_valid
     get :get_valid_record
-    assert_valid assigns('record')
+    assert_deprecated { assert_valid assigns('record') }
   end
 
   def test_assert_valid_failing
     get :get_invalid_record
 
     begin
-      assert_valid assigns('record')
+      assert_deprecated { assert_valid assigns('record') }
       assert false
     rescue ActiveSupport::TestCase::Assertion => e
     end