Report the attribute on ActiveRecord::SerializationTypeMismatch

2 files changed, 27 insertions, 11 deletions

diff --git a/activerecord/test/cases/coders/yaml_column_test.rb b/activerecord/test/cases/coders/yaml_column_test.rb
index b9c6224425..1e0b4580af 100644
--- a/activerecord/test/cases/coders/yaml_column_test.rb
+++ b/activerecord/test/cases/coders/yaml_column_test.rb
@@ -5,46 +5,48 @@ module ActiveRecord
   module Coders
     class YAMLColumnTest < ActiveRecord::TestCase
       def test_initialize_takes_class
-        coder = YAMLColumn.new(Object)
+        coder = YAMLColumn.new("attr_name", Object)
         assert_equal Object, coder.object_class
       end
 
       def test_type_mismatch_on_different_classes_on_dump
-        coder = YAMLColumn.new(Array)
-        assert_raises(SerializationTypeMismatch) do
+        coder = YAMLColumn.new("attr_name", Array)
+        error = assert_raises(SerializationTypeMismatch) do
           coder.dump("a")
         end
+        assert_equal %{Attribute `attr_name` was supposed to be a Array, but was a String. -- "a"}, error.to_s
       end
 
       def test_type_mismatch_on_different_classes
-        coder = YAMLColumn.new(Array)
-        assert_raises(SerializationTypeMismatch) do
+        coder = YAMLColumn.new("attr_name", Array)
+        error = assert_raises(SerializationTypeMismatch) do
           coder.load "--- foo"
         end
+        assert_equal %{Attribute `attr_name` was supposed to be a Array, but was a String. -- "foo"}, error.to_s
       end
 
       def test_nil_is_ok
-        coder = YAMLColumn.new
+        coder = YAMLColumn.new("attr_name")
         assert_nil coder.load "--- "
       end
 
       def test_returns_new_with_different_class
-        coder = YAMLColumn.new SerializationTypeMismatch
+        coder = YAMLColumn.new("attr_name", SerializationTypeMismatch)
         assert_equal SerializationTypeMismatch, coder.load("--- ").class
       end
 
       def test_returns_string_unless_starts_with_dash
-        coder = YAMLColumn.new
+        coder = YAMLColumn.new("attr_name")
         assert_equal "foo", coder.load("foo")
       end
 
       def test_load_handles_other_classes
-        coder = YAMLColumn.new
+        coder = YAMLColumn.new("attr_name")
         assert_equal [], coder.load([])
       end
 
       def test_load_doesnt_swallow_yaml_exceptions
-        coder = YAMLColumn.new
+        coder = YAMLColumn.new("attr_name")
         bad_yaml = "--- {"
         assert_raises(Psych::SyntaxError) do
           coder.load(bad_yaml)
@@ -52,7 +54,7 @@ module ActiveRecord
       end
 
       def test_load_doesnt_handle_undefined_class_or_module
-        coder = YAMLColumn.new
+        coder = YAMLColumn.new("attr_name")
         missing_class_yaml = '--- !ruby/object:DoesNotExistAndShouldntEver {}\n'
         assert_raises(ArgumentError) do
           coder.load(missing_class_yaml)
diff --git a/activerecord/test/cases/serialized_attribute_test.rb b/activerecord/test/cases/serialized_attribute_test.rb
index a469da0a5b..24b83691f6 100644
--- a/activerecord/test/cases/serialized_attribute_test.rb
+++ b/activerecord/test/cases/serialized_attribute_test.rb
@@ -240,6 +240,20 @@ class SerializedAttributeTest < ActiveRecord::TestCase
     assert_equal [], light.long_state
   end
 
+  def test_unexpected_serialized_type
+    Topic.serialize :content, Hash
+    topic = Topic.create!(content: { zomg: true })
+
+    Topic.serialize :content, Array
+
+    topic.reload
+    error = assert_raise(ActiveRecord::SerializationTypeMismatch) do
+      topic.content
+    end
+    expected = "Attribute `content` was supposed to be a Array, but was a Hash. -- {:zomg=>true}"
+    assert_equal expected, error.to_s
+  end
+
   def test_serialized_column_should_unserialize_after_update_column
     t = Topic.create(content: "first")
     assert_equal("first", t.content)