John Wulff

class CreateNodes < ActiveRecord::Migration
  def self.up
    create_table :nodes do |t|
      t.column :boolean_var, :boolean, :default => 0
    end
  end
end

class Node < ActiveRecord::Base
  validates_presence_of :boolean_var
end

class NodeTest < Test::Unit::TestCase
  def test_boolean_var
    node = Node.new
    node.boolean_var = 0
    node.save!
  end
end

  1) Error:
 test_boolean_var(NodeTest):
 ActiveRecord::RecordInvalid: Validation failed: Boolean var can't be blank
 /opt/local/lib/ruby/gems/1.8/gems/activerecord-1.14.2/lib/active_record/validations.rb:736:in
 `save!'
    /Users/jwulff/Development/NodeTestApp/test/unit/node_test.rb:5:in
 `test_boolean_var'

 1 tests, 0 assertions, 0 failures, 1 errors

validates_inclusion_of :boolean_var, :in => [true, false]