Remove :timestamp column type

The `:timestamp` type for columns is unused. All database adapters treat
them as the same database type. All code in `ActiveRecord` which changes
its behavior based on the column's type acts the same in both cases.
However, when the type is passed to code that checks for the `:datetime`
type, but not `:timestamp` (such as XML serialization), the result is
unexpected behavior.

Existing schema definitions will continue to work, and the `timestamp`
type is transparently aliased to `datetime`.

1 files changed, 8 insertions, 13 deletions

diff --git a/activerecord/test/cases/column_test.rb b/activerecord/test/cases/column_test.rb
index 91605a52f9..fffcb19e56 100644
--- a/activerecord/test/cases/column_test.rb
+++ b/activerecord/test/cases/column_test.rb
@@ -109,19 +109,14 @@ module ActiveRecord
       end
 
       def test_type_cast_datetime_and_timestamp
-        columns = [
-          Column.new("field", nil, Type::DateTime.new),
-          Column.new("field", nil, Type::Timestamp.new),
-        ]
-        columns.each do |column|
-          assert_equal nil, column.type_cast(nil)
-          assert_equal nil, column.type_cast('')
-          assert_equal nil, column.type_cast('  ')
-          assert_equal nil, column.type_cast('ABC')
-
-          datetime_string = Time.now.utc.strftime("%FT%T")
-          assert_equal datetime_string, column.type_cast(datetime_string).strftime("%FT%T")
-        end
+        column = Column.new("field", nil, Type::DateTime.new)
+        assert_equal nil, column.type_cast(nil)
+        assert_equal nil, column.type_cast('')
+        assert_equal nil, column.type_cast('  ')
+        assert_equal nil, column.type_cast('ABC')
+
+        datetime_string = Time.now.utc.strftime("%FT%T")
+        assert_equal datetime_string, column.type_cast(datetime_string).strftime("%FT%T")
       end
 
       def test_type_cast_date