Remove unused assignments from activerecord tests

activerecord/test/cases/associations/eager_load_nested_include_test.rb

@@ -92,7 +92,6 @@ def generate_test_object_graphs
   end
 
   def test_include_query
-    res = 0
     res = ShapeExpression.scoped(:includes => [ :shape, { :paint => :non_poly } ]).all
     assert_equal NUM_SHAPE_EXPRESSIONS, res.size
     assert_queries(0) do

activerecord/test/cases/attribute_methods_test.rb

@@ -481,7 +481,7 @@ def test_should_unserialize_attributes_for_frozen_records
   end
 
   def test_typecast_attribute_from_select_to_false
-    topic = Topic.create(:title => 'Budget')
+    Topic.create(:title => 'Budget')
     # Oracle does not support boolean expressions in SELECT
     if current_adapter?(:OracleAdapter)
       topic = Topic.scoped(:select => "topics.*, 0 as is_test").first
@@ -492,7 +492,7 @@ def test_typecast_attribute_from_select_to_false
   end
 
   def test_typecast_attribute_from_select_to_true
-    topic = Topic.create(:title => 'Budget')
+    Topic.create(:title => 'Budget')
     # Oracle does not support boolean expressions in SELECT
     if current_adapter?(:OracleAdapter)
       topic = Topic.scoped(:select => "topics.*, 1 as is_test").first

activerecord/test/cases/invalid_date_test.rb

@@ -7,8 +7,6 @@ def test_assign_valid_dates
 
     invalid_dates = [[2007, 11, 31], [1993, 2, 29], [2007, 2, 29]]
 
-    topic = Topic.new
-
     valid_dates.each do |date_src|
       topic = Topic.new("last_read(1i)" => date_src[0].to_s, "last_read(2i)" => date_src[1].to_s, "last_read(3i)" => date_src[2].to_s)
       # Oracle DATE columns are datetime columns and Oracle adapter returns Time value

activerecord/test/cases/persistence_test.rb

@@ -405,7 +405,6 @@ def test_update_attribute_for_readonly_attribute
 
   def test_update_attribute_with_one_updated
     t = Topic.first
-    title = t.title
     t.update_attribute(:title, 'super_title')
     assert_equal 'super_title', t.title
     assert !t.changed?, "topic should not have changed"