Fix bug when enum value is nil

CHANGELOG.md

@@ -3,7 +3,7 @@ CHANGELOG
 
 - **Unreleased**
   * [View Diff](https://github.com/westonganger/active_snapshot/compare/v0.5.0...master)
-  * Nothing yet
+  * [#63](https://github.com/westonganger/active_snapshot/pull/63) - Fix bug when enum value is nil
 
 - **v0.5.0** - Nov 8, 2024
   * [View Diff](https://github.com/westonganger/active_snapshot/compare/v0.4.0...v0.5.0)

lib/active_snapshot/models/snapshot.rb

@@ -46,15 +46,16 @@ def metadata=(h)
     end
 
     def build_snapshot_item(instance, child_group_name: nil)
-      attributes = instance.attributes
-      attributes.each do |k, v|
-        if instance.class.defined_enums.key?(k)
-          attributes[k] = instance.class.defined_enums.fetch(k).fetch(v)
-        end
+      attrs = instance.attributes
+
+      instance.class.defined_enums.each do |enum_col_name, hash|
+        val = attrs.fetch(enum_col_name)
+        next if val.nil?
+        attrs[enum_col_name] = hash.fetch(val)
       end
 
       self.snapshot_items.new({
-        object: attributes,
+        object: attrs,
         item_id: instance.id,
         item_type: instance.class.name,
         child_group_name: child_group_name,

test/models/snapshot_test.rb

@@ -88,14 +88,37 @@ def test_build_snapshot_item
     @snapshot.build_snapshot_item(Post.first, child_group_name: :foobar)
   end
 
-  def test_build_snapshot_item_stores_enum_database_value
-    @snapshot = @snapshot_klass.first
+  def test_snapshot_item_stores_enum_column_database_value
+    post = Post.first
 
-    snapshot_item = @snapshot.build_snapshot_item(Post.first)
+    enum_mapping = post.class.defined_enums.fetch("status")
+
+    post.status = "published"
+
+    snapshot = post.create_snapshot!(identifier: "enum-test")
+
+    snapshot_item = snapshot.snapshot_items.find_by(item_type: "Post")
+
+    stored_value = snapshot_item.object["status"]
+
+    assert_equal 1, stored_value
+    assert_equal "published", enum_mapping.invert.fetch(stored_value)
+  end
+
+  def test_snapshot_item_handles_nil_enum_column_value
+    post = Post.first
+
+    enum_mapping = post.class.defined_enums.fetch("status")
+
+    post.status = nil
+
+    snapshot = post.create_snapshot!(identifier: "enum-test")
+
+    snapshot_item = snapshot.snapshot_items.find_by(item_type: "Post")
 
-    assert snapshot_item.object['status'] == 0
+    stored_value = snapshot_item.object["status"]
 
-    assert_equal @snapshot.snapshot_items.first.object['status'], snapshot_item.object['status']
+    assert_equal nil, stored_value
   end
 
   def test_restore