Add presence validation for object in SnapshotItem model (#56)

lib/active_snapshot/models/snapshot_item.rb

@@ -12,22 +12,21 @@ class SnapshotItem < ActiveRecord::Base
     validates :snapshot_id, presence: true
     validates :item_id, presence: true, uniqueness: { scope: [:snapshot_id, :item_type] }
     validates :item_type, presence: true
+    validates :object, presence: true
 
     def object
       return @object if @object
 
       if ActiveSnapshot.config.storage_method_json?
-        @object = JSON.parse(self[:object])
+        @object = self[:object] ? JSON.parse(self[:object]) : {}
       elsif ActiveSnapshot.config.storage_method_yaml?
-        yaml_method = "unsafe_load"
+        yaml_method = YAML.respond_to?(:unsafe_load) ? :unsafe_load : :load
 
-        if !YAML.respond_to?("unsafe_load")
-          yaml_method = "load"
-        end
-
-        @object = YAML.send(yaml_method, self[:object])
+        @object = self[:object] ? YAML.public_send(yaml_method, self[:object]) : {}
       elsif ActiveSnapshot.config.storage_method_native_json?
         @object = self[:object]
+      else
+        raise StandardError, "Unsupported storage_method: `#{ActiveSnapshot.config.storage_method}`"
       end
     end
 

test/models/snapshot_item_test.rb

@@ -20,7 +20,7 @@ def test_relationships
       instance.snapshot = instance
     end
 
-    instance.snapshot = ActiveSnapshot::Snapshot.new
+    instance.snapshot = @snapshot_klass.new
 
     instance.item = instance
 
@@ -31,9 +31,9 @@ def test_relationships
   def test_validations
     instance = @snapshot_item_klass.new
 
-    instance.valid?
+    assert instance.invalid?
 
-    [:item_id, :item_type, :snapshot_id].each do |attr|
+    [:item_id, :item_type, :snapshot_id, :object].each do |attr|
       assert_equal ["can't be blank"], instance.errors[attr] ### presence error
     end
 
@@ -42,7 +42,7 @@ def test_validations
 
     instance = @snapshot_item_klass.new(item: snapshot.item, snapshot: snapshot)
 
-    assert_not instance.valid?
+    assert instance.invalid?
 
     assert_equal ["has already been taken"], instance.errors[:item_id] ### uniq error
   end