diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 284ae6695b..95d76ae456 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1756,7 +1756,8 @@ def join_base
           end
 
           def count_aliases_from_table_joins(name)
-            quoted_name = join_base.active_record.connection.quote_table_name(name.downcase)
+            # quoted_name should be downcased as some database adapters (Oracle) return quoted name in uppercase
+            quoted_name = join_base.active_record.connection.quote_table_name(name.downcase).downcase
             join_sql = join_base.table_joins.to_s.downcase
             join_sql.blank? ? 0 :
               # Table names
diff --git a/activerecord/lib/active_record/relation.rb b/activerecord/lib/active_record/relation.rb
index 4e62187449..99c914d7fc 100644
--- a/activerecord/lib/active_record/relation.rb
+++ b/activerecord/lib/active_record/relation.rb
@@ -356,13 +356,16 @@ def with_create_scope
     end
 
     def references_eager_loaded_tables?
-      joined_tables = (tables_in_string(arel.joins(arel)) + [table.name, table.table_alias]).compact.uniq
+      # always convert table names to downcase as in Oracle quoted table names are in uppercase
+      joined_tables = (tables_in_string(arel.joins(arel)) + [table.name, table.table_alias]).compact.map(&:downcase).uniq
       (tables_in_string(to_sql) - joined_tables).any?
     end
 
     def tables_in_string(string)
       return [] if string.blank?
-      string.scan(/([a-zA-Z_][\.\w]+).?\./).flatten.uniq
+      # always convert table names to downcase as in Oracle quoted table names are in uppercase
+      # ignore raw_sql_ that is used by Oracle adapter as alias for limit/offset subqueries
+      string.scan(/([a-zA-Z_][\.\w]+).?\./).flatten.map(&:downcase).uniq - ['raw_sql_']
     end
 
   end
diff --git a/activerecord/test/cases/adapter_test.rb b/activerecord/test/cases/adapter_test.rb
index 9b28766405..0152b7be2a 100644
--- a/activerecord/test/cases/adapter_test.rb
+++ b/activerecord/test/cases/adapter_test.rb
@@ -145,22 +145,13 @@ def test_foreign_key_violations_are_translated_to_specific_exception
 
   def test_add_limit_offset_should_sanitize_sql_injection_for_limit_without_comas
     sql_inject = "1 select * from schema"
-      assert_equal " LIMIT 1", @connection.add_limit_offset!("", :limit => sql_inject)
-    if current_adapter?(:MysqlAdapter)
-      assert_equal " LIMIT 7, 1", @connection.add_limit_offset!("", :limit => sql_inject, :offset => 7)
-    else
-      assert_equal " LIMIT 1 OFFSET 7", @connection.add_limit_offset!("", :limit => sql_inject, :offset => 7)
-    end
+    assert_no_match /schema/, @connection.add_limit_offset!("", :limit=>sql_inject)
+    assert_no_match /schema/, @connection.add_limit_offset!("", :limit=>sql_inject, :offset=>7)
   end
 
   def test_add_limit_offset_should_sanitize_sql_injection_for_limit_with_comas
     sql_inject = "1, 7 procedure help()"
-    if current_adapter?(:MysqlAdapter)
-      assert_equal " LIMIT 1,7", @connection.add_limit_offset!("", :limit => sql_inject)
-      assert_equal " LIMIT 7, 1", @connection.add_limit_offset!("", :limit => '1 ; DROP TABLE USERS', :offset => 7)
-    else
-      assert_equal " LIMIT 1,7", @connection.add_limit_offset!("", :limit => sql_inject)
-      assert_equal " LIMIT 1,7 OFFSET 7", @connection.add_limit_offset!("", :limit => sql_inject, :offset => 7)
-    end
+    assert_no_match /procedure/, @connection.add_limit_offset!("", :limit=>sql_inject)
+    assert_no_match /procedure/, @connection.add_limit_offset!("", :limit=>sql_inject, :offset=>7)
   end
 end
diff --git a/activerecord/test/cases/associations/belongs_to_associations_test.rb b/activerecord/test/cases/associations/belongs_to_associations_test.rb
index 9258c987ef..fb1e6e7e70 100644
--- a/activerecord/test/cases/associations/belongs_to_associations_test.rb
+++ b/activerecord/test/cases/associations/belongs_to_associations_test.rb
@@ -37,6 +37,10 @@ def test_belongs_to_with_primary_key_joins_on_correct_column
     if current_adapter?(:MysqlAdapter)
       assert_no_match(/`firm_with_primary_keys_companies`\.`id`/, sql)
       assert_match(/`firm_with_primary_keys_companies`\.`name`/, sql)
+    elsif current_adapter?(:OracleAdapter)
+      # on Oracle aliases are truncated to 30 characters and are quoted in uppercase
+      assert_no_match(/"firm_with_primary_keys_compani"\."id"/i, sql)
+      assert_match(/"firm_with_primary_keys_compani"\."name"/i, sql)
     else
       assert_no_match(/"firm_with_primary_keys_companies"\."id"/, sql)
       assert_match(/"firm_with_primary_keys_companies"\."name"/, sql)
diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index 8e5bc56008..45c7498013 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -511,7 +511,7 @@ def test_deleting_before_save
   end
 
   def test_deleting_updates_counter_cache
-    topic = Topic.first
+    topic = Topic.first(:order => "id ASC")
     assert_equal topic.replies.to_a.size, topic.replies_count
 
     topic.replies.delete(topic.replies.first)
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 1d883f7ea8..36c572b5e7 100755
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -430,14 +430,14 @@ def test_non_attribute_access_and_assignment
   end
 
   def test_preserving_date_objects
-    if current_adapter?(:SybaseAdapter, :OracleAdapter)
+    if current_adapter?(:SybaseAdapter)
       # Sybase ctlib does not (yet?) support the date type; use datetime instead.
-      # Oracle treats all dates/times as Time.
       assert_kind_of(
         Time, Topic.find(1).last_read,
         "The last_read attribute should be of the Time class"
       )
     else
+      # Oracle enhanced adapter allows to define Date attributes in model class (see topic.rb)
       assert_kind_of(
         Date, Topic.find(1).last_read,
         "The last_read attribute should be of the Date class"
@@ -2125,10 +2125,11 @@ def test_to_xml
     assert_equal "integer", xml.elements["//parent-id"].attributes['type']
     assert_equal "true", xml.elements["//parent-id"].attributes['nil']
 
-    if current_adapter?(:SybaseAdapter, :OracleAdapter)
+    if current_adapter?(:SybaseAdapter)
       assert_equal last_read_in_current_timezone, xml.elements["//last-read"].text
       assert_equal "datetime" , xml.elements["//last-read"].attributes['type']
     else
+      # Oracle enhanced adapter allows to define Date attributes in model class (see topic.rb)
       assert_equal "2004-04-15", xml.elements["//last-read"].text
       assert_equal "date" , xml.elements["//last-read"].attributes['type']
     end
diff --git a/activerecord/test/cases/date_time_test.rb b/activerecord/test/cases/date_time_test.rb
index 36e1caa0b6..a8b4b7a096 100644
--- a/activerecord/test/cases/date_time_test.rb
+++ b/activerecord/test/cases/date_time_test.rb
@@ -5,7 +5,9 @@
 class DateTimeTest < ActiveRecord::TestCase
   def test_saves_both_date_and_time
     time_values = [1807, 2, 10, 15, 30, 45]
-    now = DateTime.civil(*time_values)
+    # create DateTime value with local time zone offset
+    local_offset = Rational(Time.local_time(*time_values).utc_offset, 86400)
+    now = DateTime.civil(*(time_values + [local_offset]))
 
     task = Task.new
     task.starting = now
diff --git a/activerecord/test/cases/log_subscriber_test.rb b/activerecord/test/cases/log_subscriber_test.rb
index 6ba84fa57b..1f544b4211 100644
--- a/activerecord/test/cases/log_subscriber_test.rb
+++ b/activerecord/test/cases/log_subscriber_test.rb
@@ -27,7 +27,7 @@ def test_basic_query_logging
     wait
     assert_equal 1, @logger.logged(:debug).size
     assert_match(/Developer Load/, @logger.logged(:debug).last)
-    assert_match(/SELECT .*?FROM .?developers.?/, @logger.logged(:debug).last)
+    assert_match(/SELECT .*?FROM .?developers.?/i, @logger.logged(:debug).last)
   end
 
   def test_cached_queries
@@ -38,6 +38,6 @@ def test_cached_queries
     wait
     assert_equal 2, @logger.logged(:debug).size
     assert_match(/CACHE/, @logger.logged(:debug).last)
-    assert_match(/SELECT .*?FROM .?developers.?/, @logger.logged(:debug).last)
+    assert_match(/SELECT .*?FROM .?developers.?/i, @logger.logged(:debug).last)
   end
 end
diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index b5fa258f7b..1edec66c25 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -30,13 +30,14 @@ def test_add_schema_info_respects_prefix_and_suffix
       conn = ActiveRecord::Base.connection
 
       conn.drop_table(ActiveRecord::Migrator.schema_migrations_table_name) if conn.table_exists?(ActiveRecord::Migrator.schema_migrations_table_name)
-      ActiveRecord::Base.table_name_prefix = 'foo_'
-      ActiveRecord::Base.table_name_suffix = '_bar'
+      # Use shorter prefix and suffix as in Oracle database identifier cannot be larger than 30 characters
+      ActiveRecord::Base.table_name_prefix = 'p_'
+      ActiveRecord::Base.table_name_suffix = '_s'
       conn.drop_table(ActiveRecord::Migrator.schema_migrations_table_name) if conn.table_exists?(ActiveRecord::Migrator.schema_migrations_table_name)
 
       conn.initialize_schema_migrations_table
 
-      assert_equal "foo_unique_schema_migrations_bar", conn.indexes(ActiveRecord::Migrator.schema_migrations_table_name)[0][:name]
+      assert_equal "p_unique_schema_migrations_s", conn.indexes(ActiveRecord::Migrator.schema_migrations_table_name)[0][:name]
     ensure
       ActiveRecord::Base.table_name_prefix = ""
       ActiveRecord::Base.table_name_suffix = ""
@@ -83,13 +84,17 @@ def test_add_index
 
       # Orcl nds shrt indx nms.  Sybs 2.
       # OpenBase does not have named indexes.  You must specify a single column name
-      unless current_adapter?(:OracleAdapter, :SybaseAdapter, :OpenBaseAdapter)
+      unless current_adapter?(:SybaseAdapter, :OpenBaseAdapter)
         assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"]) }
         assert_nothing_raised { Person.connection.remove_index("people", :column => ["last_name", "first_name"]) }
-        assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"]) }
-        assert_nothing_raised { Person.connection.remove_index("people", :name => "index_people_on_last_name_and_first_name") }
-        assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"]) }
-        assert_nothing_raised { Person.connection.remove_index("people", "last_name_and_first_name") }
+        # Oracle adapter cannot have specified index name larger than 30 characters
+        # Oracle adapter is shortening index name when just column list is given
+        unless current_adapter?(:OracleAdapter)
+          assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"]) }
+          assert_nothing_raised { Person.connection.remove_index("people", :name => "index_people_on_last_name_and_first_name") }
+          assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"]) }
+          assert_nothing_raised { Person.connection.remove_index("people", "last_name_and_first_name") }
+        end
         assert_nothing_raised { Person.connection.add_index("people", ["last_name", "first_name"]) }
         assert_nothing_raised { Person.connection.remove_index("people", ["last_name", "first_name"]) }
         assert_nothing_raised { Person.connection.add_index("people", ["last_name"], :length => 10) }
@@ -736,13 +741,7 @@ def test_remove_column_with_multi_column_index
         table.column :hat_size, :integer
         table.column :hat_style, :string, :limit => 100
       end
-      # Oracle index names should be 30 or less characters
-      if current_adapter?(:OracleAdapter)
-        ActiveRecord::Base.connection.add_index "hats", ["hat_style", "hat_size"], :unique => true,
-          :name => 'index_hats_on_hat_style_size'
-      else
-        ActiveRecord::Base.connection.add_index "hats", ["hat_style", "hat_size"], :unique => true
-      end
+      ActiveRecord::Base.connection.add_index "hats", ["hat_style", "hat_size"], :unique => true
 
       assert_nothing_raised { Person.connection.remove_column("hats", "hat_size") }
     ensure
@@ -1375,8 +1374,8 @@ def test_create_table_with_custom_sequence_name
       return unless current_adapter? :OracleAdapter
 
       # table name is 29 chars, the standard sequence name will
-      # be 33 chars and fail
-      assert_raise(ActiveRecord::StatementInvalid) do
+      # be 33 chars and should be shortened
+      assert_nothing_raised do
         begin
           Person.connection.create_table :table_with_name_thats_just_ok do |t|
             t.column :foo, :string, :null => false
diff --git a/activerecord/test/connections/native_oracle/connection.rb b/activerecord/test/connections/native_oracle/connection.rb
index c8183dc0fb..bb4040058f 100644
--- a/activerecord/test/connections/native_oracle/connection.rb
+++ b/activerecord/test/connections/native_oracle/connection.rb
@@ -53,7 +53,7 @@
 
 # for assert_queries test helper
 ActiveRecord::Base.connection.class.class_eval do
-  IGNORED_SELECT_SQL = [/^select .*nextval/i, /^SAVEPOINT/, /^ROLLBACK TO SAVEPOINT/, /^RELEASE SAVEPOINT/, /^\s*select .* from all_tab_columns/im]
+  IGNORED_SELECT_SQL = [/^select .*nextval/i, /^SAVEPOINT/, /^ROLLBACK TO/, /^\s*select .* from ((all|user)_tab_columns|(all|user)_triggers|(all|user)_constraints)/im]
 
   def select_with_query_record(sql, name = nil, return_column_names = false)
     $queries_executed ||= []
diff --git a/activerecord/test/models/topic.rb b/activerecord/test/models/topic.rb
index 91fc7c9416..617f01b47d 100644
--- a/activerecord/test/models/topic.rb
+++ b/activerecord/test/models/topic.rb
@@ -43,6 +43,12 @@ def extension_two
   before_create  :default_written_on
   before_destroy :destroy_children
 
+  # Explicitly define as :date column so that returned Oracle DATE values would be typecasted to Date and not Time.
+  # Some tests depend on assumption that this attribute will have Date values.
+  if current_adapter?(:OracleEnhancedAdapter)
+    set_date_columns :last_read
+  end
+
   def parent
     Topic.find(parent_id)
   end
diff --git a/activesupport/lib/active_support/core_ext/date_time/conversions.rb b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
index 24168c7825..c3f0acce25 100644
--- a/activesupport/lib/active_support/core_ext/date_time/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/date_time/conversions.rb
@@ -60,7 +60,7 @@ def readable_inspect
   # Converts self to a Ruby Date object; time portion is discarded
   def to_date
     ::Date.new(year, month, day)
-  end unless method_defined?(:to_date)
+  end unless instance_methods(false).include?(:to_date)
 
   # Attempts to convert self to a Ruby Time object; returns self if out of range of Ruby Time class
   # If self has an offset other than 0, self will just be returned unaltered, since there's no clean way to map it to a Time
@@ -71,7 +71,7 @@ def to_time
   # To be able to keep Times, Dates and DateTimes interchangeable on conversions
   def to_datetime
     self
-  end unless method_defined?(:to_datetime)
+  end unless instance_methods(false).include?(:to_datetime)
 
   def self.civil_from_format(utc_or_local, year, month=1, day=1, hour=0, min=0, sec=0)
     offset = utc_or_local.to_sym == :local ? local_offset : 0
@@ -81,7 +81,7 @@ def self.civil_from_format(utc_or_local, year, month=1, day=1, hour=0, min=0, se
   # Converts datetime to an appropriate format for use in XML
   def xmlschema
     strftime("%Y-%m-%dT%H:%M:%S%Z")
-  end unless method_defined?(:xmlschema)
+  end unless instance_methods(false).include?(:xmlschema)
   
   # Converts self to a floating-point number of seconds since the Unix epoch 
   def to_f
diff --git a/activesupport/test/abstract_unit.rb b/activesupport/test/abstract_unit.rb
index ea6ebca3ce..dd84860a91 100644
--- a/activesupport/test/abstract_unit.rb
+++ b/activesupport/test/abstract_unit.rb
@@ -18,7 +18,7 @@
 require 'active_support'
 
 # Include shims until we get off 1.8.6
-require 'active_support/ruby/shim'
+require 'active_support/ruby/shim' if RUBY_VERSION < '1.8.7'
 
 def uses_memcached(test_name)
   require 'memcache'
diff --git a/activesupport/test/core_ext/date_time_ext_test.rb b/activesupport/test/core_ext/date_time_ext_test.rb
index eba8170cda..19d7935211 100644
--- a/activesupport/test/core_ext/date_time_ext_test.rb
+++ b/activesupport/test/core_ext/date_time_ext_test.rb
@@ -26,11 +26,11 @@ def test_custom_date_format
   end
 
   def test_to_date
-    assert_equal Date.new(2005, 2, 21), DateTime.new(2005, 2, 21).to_date
+    assert_equal Date.new(2005, 2, 21), DateTime.new(2005, 2, 21, 14, 30, 0).to_date
   end
 
   def test_to_datetime
-    assert_equal DateTime.new(2005, 2, 21), DateTime.new(2005, 2, 21).to_datetime
+    assert_equal DateTime.new(2005, 2, 21, 14, 30, 0), DateTime.new(2005, 2, 21, 14, 30, 0).to_datetime
   end
 
   def test_to_time