fix: limit of enum columns of mysql

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -72,6 +72,8 @@ module ActiveRecord
           when /^mediumint/i; 3
           when /^smallint/i;  2
           when /^tinyint/i;   1
+          when /^enum\((.+)\)/i
+            $1.split(',').map{|enum| enum.strip.length - 2}.max
           else
             super
           end

activerecord/test/cases/adapters/mysql/enum_test.rb

@@ -0,0 +1,10 @@
+require "cases/helper"
+
+class MysqlEnumTest < ActiveRecord::TestCase
+  class EnumTest < ActiveRecord::Base
+  end
+
+  def test_enum_limit
+    assert_equal 5, EnumTest.columns.first.limit
+  end
+end

activerecord/test/cases/adapters/mysql2/enum_test.rb

@@ -0,0 +1,10 @@
+require "cases/helper"
+
+class Mysql2EnumTest < ActiveRecord::TestCase
+  class EnumTest < ActiveRecord::Base
+  end
+
+  def test_enum_limit
+    assert_equal 5, EnumTest.columns.first.limit
+  end
+end

activerecord/test/schema/mysql2_specific_schema.rb

@@ -32,4 +32,13 @@ CREATE TABLE collation_tests (
 ) CHARACTER SET utf8 COLLATE utf8_general_ci
 SQL
 
+  ActiveRecord::Base.connection.execute <<-SQL
+DROP TABLE IF EXISTS enum_tests;
+SQL
+
+  ActiveRecord::Base.connection.execute <<-SQL
+CREATE TABLE enum_tests (
+  enum_column ENUM('true','false')
+)
+SQL
 end

activerecord/test/schema/mysql_specific_schema.rb

@@ -41,6 +41,16 @@ CREATE TABLE collation_tests (
   string_cs_column VARCHAR(1) COLLATE utf8_bin,
   string_ci_column VARCHAR(1) COLLATE utf8_general_ci
 ) CHARACTER SET utf8 COLLATE utf8_general_ci
+SQL
+
+  ActiveRecord::Base.connection.execute <<-SQL
+DROP TABLE IF EXISTS enum_tests;
+SQL
+
+  ActiveRecord::Base.connection.execute <<-SQL
+CREATE TABLE enum_tests (
+  enum_column ENUM('true','false')
+)
 SQL
 
 end