Use the correct values for int max and min

We had accidentally gone one power of two too far. In addition, we need
to handle minimum values as well as the maximum.

3 files changed, 119 insertions, 56 deletions

diff --git a/activerecord/lib/active_record/type/integer.rb b/activerecord/lib/active_record/type/integer.rb
index 2b0f0b2734..d69e5b3f28 100644
--- a/activerecord/lib/active_record/type/integer.rb
+++ b/activerecord/lib/active_record/type/integer.rb
@@ -3,12 +3,21 @@ module ActiveRecord
     class Integer < Value # :nodoc:
       include Numeric
 
+      def initialize(*)
+        super
+        @range = -max_value...max_value
+      end
+
       def type
         :integer
       end
 
       alias type_cast_for_database type_cast
 
+      protected
+
+      attr_reader :range
+
       private
 
       def cast_value(value)
@@ -17,25 +26,20 @@ module ActiveRecord
         when false then 0
         else
           result = value.to_i rescue nil
-          ensure_below_max(result) if result
+          ensure_in_range(result) if result
           result
         end
       end
 
-      def ensure_below_max(value)
-        if value > max_value
+      def ensure_in_range(value)
+        unless range.cover?(value)
           raise RangeError, "#{value} is too large for #{self.class} with limit #{limit || 4}"
         end
       end
 
       def max_value
-        @max_value = determine_max_value unless defined?(@max_value)
-        @max_value
-      end
-
-      def determine_max_value
         limit = self.limit || 4
-        2 << (limit * 8 - 1) # 8 bits per byte with one bit for sign
+        1 << (limit * 8 - 1) # 8 bits per byte with one bit for sign
       end
     end
   end
diff --git a/activerecord/test/cases/type/integer_test.rb b/activerecord/test/cases/type/integer_test.rb
new file mode 100644
index 0000000000..53d6a3a6aa
--- /dev/null
+++ b/activerecord/test/cases/type/integer_test.rb
@@ -0,0 +1,106 @@
+require "cases/helper"
+require "models/company"
+
+module ActiveRecord
+  module Type
+    class IntegerTest < ActiveRecord::TestCase
+      test "simple values" do
+        type = Type::Integer.new
+        assert_equal 1, type.type_cast_from_user(1)
+        assert_equal 1, type.type_cast_from_user('1')
+        assert_equal 1, type.type_cast_from_user('1ignore')
+        assert_equal 0, type.type_cast_from_user('bad1')
+        assert_equal 0, type.type_cast_from_user('bad')
+        assert_equal 1, type.type_cast_from_user(1.7)
+        assert_equal 0, type.type_cast_from_user(false)
+        assert_equal 1, type.type_cast_from_user(true)
+        assert_nil type.type_cast_from_user(nil)
+      end
+
+      test "random objects cast to nil" do
+        type = Type::Integer.new
+        assert_nil type.type_cast_from_user([1,2])
+        assert_nil type.type_cast_from_user({1 => 2})
+        assert_nil type.type_cast_from_user((1..2))
+      end
+
+      test "casting ActiveRecord models" do
+        type = Type::Integer.new
+        firm = Firm.create(:name => 'Apple')
+        assert_nil type.type_cast_from_user(firm)
+      end
+
+      test "casting objects without to_i" do
+        type = Type::Integer.new
+        assert_nil type.type_cast_from_user(::Object.new)
+      end
+
+      test "casting nan and infinity" do
+        type = Type::Integer.new
+        assert_nil type.type_cast_from_user(::Float::NAN)
+        assert_nil type.type_cast_from_user(1.0/0.0)
+      end
+
+      test "changed?" do
+        type = Type::Integer.new
+
+        assert type.changed?(5, 5, '5wibble')
+        assert_not type.changed?(5, 5, '5')
+        assert_not type.changed?(5, 5, '5.0')
+        assert_not type.changed?(nil, nil, nil)
+      end
+
+      test "values below int min value are out of range" do
+        assert_raises(::RangeError) do
+          Integer.new.type_cast_from_user("-2147483649")
+        end
+      end
+
+      test "values above int max value are out of range" do
+        assert_raises(::RangeError) do
+          Integer.new.type_cast_from_user("2147483648")
+        end
+      end
+
+      test "very small numbers are out of range" do
+        assert_raises(::RangeError) do
+          Integer.new.type_cast_from_user("-9999999999999999999999999999999")
+        end
+      end
+
+      test "very large numbers are in range" do
+        assert_raises(::RangeError) do
+          Integer.new.type_cast_from_user("9999999999999999999999999999999")
+        end
+      end
+
+      test "normal numbers are in range" do
+        type = Integer.new
+        assert_equal(0, type.type_cast_from_user("0"))
+        assert_equal(-1, type.type_cast_from_user("-1"))
+        assert_equal(1, type.type_cast_from_user("1"))
+      end
+
+      test "int max value is in range" do
+        assert_equal(2147483647, Integer.new.type_cast_from_user("2147483647"))
+      end
+
+      test "int min value is in range" do
+        assert_equal(-2147483648, Integer.new.type_cast_from_user("-2147483648"))
+      end
+
+      test "columns with a larger limit have larger ranges" do
+        type = Integer.new(limit: 8)
+
+        assert_equal(9223372036854775807, type.type_cast_from_user("9223372036854775807"))
+        assert_equal(-9223372036854775808, type.type_cast_from_user("-9223372036854775808"))
+        assert_raises(::RangeError) do
+          type.type_cast_from_user("-9999999999999999999999999999999")
+        end
+        assert_raises(::RangeError) do
+          type.type_cast_from_user("9999999999999999999999999999999")
+        end
+      end
+    end
+  end
+end
diff --git a/activerecord/test/cases/types_test.rb b/activerecord/test/cases/types_test.rb
index 25e6549072..b0979cbe1f 100644
--- a/activerecord/test/cases/types_test.rb
+++ b/activerecord/test/cases/types_test.rb
@@ -1,5 +1,4 @@
 require "cases/helper"
-require 'models/company'
 
 module ActiveRecord
   module ConnectionAdapters
@@ -37,52 +36,6 @@ module ActiveRecord
         end
       end
 
-      def test_type_cast_integer
-        type = Type::Integer.new
-        assert_equal 1, type.type_cast_from_user(1)
-        assert_equal 1, type.type_cast_from_user('1')
-        assert_equal 1, type.type_cast_from_user('1ignore')
-        assert_equal 0, type.type_cast_from_user('bad1')
-        assert_equal 0, type.type_cast_from_user('bad')
-        assert_equal 1, type.type_cast_from_user(1.7)
-        assert_equal 0, type.type_cast_from_user(false)
-        assert_equal 1, type.type_cast_from_user(true)
-        assert_nil type.type_cast_from_user(nil)
-      end
-
-      def test_type_cast_non_integer_to_integer
-        type = Type::Integer.new
-        assert_nil type.type_cast_from_user([1,2])
-        assert_nil type.type_cast_from_user({1 => 2})
-        assert_nil type.type_cast_from_user((1..2))
-      end
-
-      def test_type_cast_activerecord_to_integer
-        type = Type::Integer.new
-        firm = Firm.create(:name => 'Apple')
-        assert_nil type.type_cast_from_user(firm)
-      end
-
-      def test_type_cast_object_without_to_i_to_integer
-        type = Type::Integer.new
-        assert_nil type.type_cast_from_user(Object.new)
-      end
-
-      def test_type_cast_nan_and_infinity_to_integer
-        type = Type::Integer.new
-        assert_nil type.type_cast_from_user(Float::NAN)
-        assert_nil type.type_cast_from_user(1.0/0.0)
-      end
-
-      def test_changing_integers
-        type = Type::Integer.new
-
-        assert type.changed?(5, 5, '5wibble')
-        assert_not type.changed?(5, 5, '5')
-        assert_not type.changed?(5, 5, '5.0')
-        assert_not type.changed?(nil, nil, nil)
-      end
-
       def test_type_cast_float
         type = Type::Float.new
         assert_equal 1.0, type.type_cast_from_user("1")