STI followup: unit tests

I'm a complete newbie when it comes to unit testing in Ruby (I started only today), but here's a unit test for yesterday's STI example.

Test data (in test/fixtures/element_defs.yml) below. Note that the first entry root_name_def is subclassed to RefComponentDef.

  root_name_def:
    type: RefComponentDef
    id: 1
  root_description_def:
    id: 2

In my tests for the parent class ElementDef it looks like I'm disregard subclassing altogether, but passing this test shows implicitly that subclasses and their objects load fine together:

  class ElementDefTest < Test::Unit::TestCase
    fixtures :element_defs
  
    # Check that the fixture data makes sense
    def test_fixtures
      assert_kind_of ElementDef, element_defs(:root_name_def)
      assert_kind_of ElementDef, element_defs(:root_description_def)
   end
  
    # Check that the loaded data makes sense
    def test_loaded_data
      assert_kind_of ElementDef, ElementDef.find_by_id(element_defs(:root_name_def)[:id])
      assert_kind_of ElementDef, ElementDef.find_by_id(element_defs(:root_description_def)[:id])
    end
 

In the subclass's tests I show that its objects can be read via the superclass's find methods:

  class RefComponentDefTest < Test::Unit::TestCase
    fixtures :element_defs

    # Check the ElementDef fixture data correctly identifies :root_name_def as a RefComponentDef
    def test_fixtures
      assert_kind_of RefComponentDef, element_defs(:root_name_def)
    end
  
    # Check that a RefComponentDef can be read back from the database via its superclass
    def test_loaded_data
       assert_kind_of RefComponentDef, ElementDef.find_by_id(element_defs(:root_name_def)[:id])
    end
  end

I could add this to the wiki - did anyone find this useful?

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