1 files changed, 80 insertions, 1 deletions
diff --git a/activerecord/test/cases/inheritance_test.rb b/activerecord/test/cases/inheritance_test.rb
index f67d85603a..52e3734dd0 100644
--- a/activerecord/test/cases/inheritance_test.rb
+++ b/activerecord/test/cases/inheritance_test.rb
@@ -1,4 +1,5 @@
 require 'cases/helper'
+require 'models/author'
 require 'models/company'
 require 'models/person'
 require 'models/post'
@@ -55,6 +56,53 @@ class InheritanceTest < ActiveRecord::TestCase
     end
   end
 
+  def test_compute_type_success
+    assert_equal Author, ActiveRecord::Base.send(:compute_type, 'Author')
+  end
+
+  def test_compute_type_nonexistent_constant
+    e = assert_raises NameError do
+      ActiveRecord::Base.send :compute_type, 'NonexistentModel'
+    end
+    assert_equal 'uninitialized constant ActiveRecord::Base::NonexistentModel', e.message
+    assert_equal 'ActiveRecord::Base::NonexistentModel', e.name
+  end
+
+  def test_compute_type_no_method_error
+    ActiveSupport::Dependencies.stub(:safe_constantize, proc{ raise NoMethodError }) do
+      assert_raises NoMethodError do
+        ActiveRecord::Base.send :compute_type, 'InvalidModel'
+      end
+    end
+  end
+
+  def test_compute_type_on_undefined_method
+    error = nil
+    begin
+      Class.new(Author) do
+        alias_method :foo, :bar
+      end
+    rescue => e
+      error = e
+    end
+
+    ActiveSupport::Dependencies.stub(:safe_constantize, proc{ raise e }) do
+
+      exception = assert_raises NameError do
+        ActiveRecord::Base.send :compute_type, 'InvalidModel'
+      end
+      assert_equal error.message, exception.message
+    end
+  end
+
+  def test_compute_type_argument_error
+    ActiveSupport::Dependencies.stub(:safe_constantize, proc{ raise ArgumentError }) do
+      assert_raises ArgumentError do
+        ActiveRecord::Base.send :compute_type, 'InvalidModel'
+      end
+    end
+  end
+
   def test_should_store_demodulized_class_name_with_store_full_sti_class_option_disabled
     without_store_full_sti_class do
       item = Namespaced::Company.new
@@ -77,6 +125,32 @@ class InheritanceTest < ActiveRecord::TestCase
     end
   end
 
+  def test_descends_from_active_record
+    assert !ActiveRecord::Base.descends_from_active_record?
+
+    # Abstract subclass of AR::Base.
+    assert LoosePerson.descends_from_active_record?
+
+    # Concrete subclass of an abstract class.
+    assert LooseDescendant.descends_from_active_record?
+
+    # Concrete subclass of AR::Base.
+    assert TightPerson.descends_from_active_record?
+
+    # Concrete subclass of a concrete class but has no type column.
+    assert TightDescendant.descends_from_active_record?
+
+    # Concrete subclass of AR::Base.
+    assert Post.descends_from_active_record?
+
+    # Abstract subclass of a concrete class which has a type column.
+    # This is pathological, as you'll never have Sub < Abstract < Concrete.
+    assert !StiPost.descends_from_active_record?
+
+    # Concrete subclasses an abstract class which has a type column.
+    assert !SubStiPost.descends_from_active_record?
+  end
+
   def test_company_descends_from_active_record
     assert !ActiveRecord::Base.descends_from_active_record?
     assert AbstractCompany.descends_from_active_record?, 'AbstractCompany should descend from ActiveRecord::Base'
@@ -84,6 +158,12 @@ class InheritanceTest < ActiveRecord::TestCase
     assert !Class.new(Company).descends_from_active_record?, 'Company subclass should not descend from ActiveRecord::Base'
   end
 
+  def test_abstract_class
+    assert !ActiveRecord::Base.abstract_class?
+    assert LoosePerson.abstract_class?
+    assert !LooseDescendant.abstract_class?
+  end
+
   def test_inheritance_base_class
     assert_equal Post, Post.base_class
     assert_equal Post, SpecialPost.base_class
@@ -223,7 +303,6 @@ class InheritanceTest < ActiveRecord::TestCase
     end
   end
 
-
   def test_new_with_complex_inheritance
     assert_nothing_raised { Client.new(type: 'VerySpecialClient') }
   end