Add content method test in model structure_item and refactor

app/models/spina/structure_item.rb

@@ -8,8 +8,7 @@ class StructureItem < ActiveRecord::Base
     accepts_nested_attributes_for :structure_parts, allow_destroy: true
 
     def content(structure_part)
-      structure_part = structure_parts.where(name: structure_part).first
-      structure_part.try(:content)
+      structure_parts.find_by(name: structure_part).try(:content)
     end
   end
 end

test/fixtures/spina/lines.yml

@@ -0,0 +1,2 @@
+line_1:
+  content: line_content_1

test/fixtures/spina/structure_items.yml

@@ -0,0 +1,5 @@
+structure_item_1:
+  structure_id: <%= ActiveRecord::FixtureSet.identify(:structure_1) %>
+
+structure_item_2:
+  structure_id: <%= ActiveRecord::FixtureSet.identify(:structure_2) %>

test/fixtures/spina/structure_parts.yml

@@ -0,0 +1,5 @@
+structure_part_1:
+  structure_item_id: <%= ActiveRecord::FixtureSet.identify(:structure_item_1) %>
+  structure_partable_id: <%= ActiveRecord::FixtureSet.identify(:line_1) %>
+  structure_partable_type: Spina::Line
+  name: name_1

test/fixtures/spina/structures.yml

@@ -0,0 +1,5 @@
+structure_1:
+  id: 1
+
+structure_2:
+  id: 2

test/models/spina/structure_item_test.rb

@@ -0,0 +1,24 @@
+require 'test_helper'
+
+module Spina
+  class StructureItemTest < ActiveSupport::TestCase
+
+    def setup
+      @structure_1 = spina_structures(:structure_1)
+
+      @structure_item_1 = spina_structure_items(:structure_item_1)
+      @structure_item_2 = spina_structure_items(:structure_item_2)
+
+      @structure_part_1 = spina_structure_parts(:structure_part_1)
+    end
+
+    test 'structure_item_1 content' do
+      assert_equal 'line_content_1', @structure_item_1.content(@structure_part_1.name)
+    end
+
+    test 'structure_item_2 content' do
+      assert_equal nil, @structure_item_2.content(@structure_part_1.name)
+    end
+
+  end
+end