Change the behavior of boolean columns to be closer to Ruby's semantics.

Before this change we had a small set of "truthy", and all others
are "falsy".

Now, we have a small set of "falsy" values and all others are
"truthy" matching Ruby's semantics.

activerecord/CHANGELOG.md

+*   Change the behavior of boolean columns to be closer to Ruby's semantics.
+
+    Before this change we had a small set of "truthy", and all others are "falsy".
+
+    Now, we have a small set of "falsy" values and all others are "truthy" matching
+    Ruby's semantics.
+
+    *Rafael Mendonça França*
+
 *   Deprecate `ActiveRecord::Base.errors_in_transactional_callbacks=`.
 
     *Rafael Mendonça França*

activerecord/lib/active_record/connection_adapters/column.rb

@@ -5,7 +5,6 @@ module ActiveRecord
   module ConnectionAdapters
     # An abstract definition of a column in a table.
     class Column
-      TRUE_VALUES = [true, 1, '1', 't', 'T', 'true', 'TRUE', 'on', 'ON'].to_set
       FALSE_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE', 'off', 'OFF'].to_set
 
       module Format

activerecord/lib/active_record/type/boolean.rb

@@ -10,19 +10,10 @@ def type
       def cast_value(value)
         if value == ''
           nil
-        elsif ConnectionAdapters::Column::TRUE_VALUES.include?(value)
-          true
-        else
-          if !ConnectionAdapters::Column::FALSE_VALUES.include?(value)
-            ActiveSupport::Deprecation.warn(<<-MSG.squish)
-              You attempted to assign a value which is not explicitly `true` or `false`
-              to a boolean column. Currently this value casts to `false`. This will
-              change to match Ruby's semantics, and will cast to `true` in Rails 5.
-              If you would like to maintain the current behavior, you should
-              explicitly handle the values you would like cast to `false`.
-            MSG
-          end
+        elsif ConnectionAdapters::Column::FALSE_VALUES.include?(value)
           false
+        else
+          true
         end
       end
     end

activerecord/test/cases/types_test.rb

@@ -17,6 +17,10 @@ def test_type_cast_boolean
         assert type.type_cast_from_user('TRUE')
         assert type.type_cast_from_user('on')
         assert type.type_cast_from_user('ON')
+        assert type.type_cast_from_user(' ')
+        assert type.type_cast_from_user("\u3000\r\n")
+        assert type.type_cast_from_user("\u0000")
+        assert type.type_cast_from_user('SOMETHING RANDOM')
 
         # explicitly check for false vs nil
         assert_equal false, type.type_cast_from_user(false)
@@ -28,12 +32,6 @@ def test_type_cast_boolean
         assert_equal false, type.type_cast_from_user('FALSE')
         assert_equal false, type.type_cast_from_user('off')
         assert_equal false, type.type_cast_from_user('OFF')
-        assert_deprecated do
-          assert_equal false, type.type_cast_from_user(' ')
-          assert_equal false, type.type_cast_from_user("\u3000\r\n")
-          assert_equal false, type.type_cast_from_user("\u0000")
-          assert_equal false, type.type_cast_from_user('SOMETHING RANDOM')
-        end
       end
 
       def test_type_cast_float