if ActiveRecord::Base.method_defined?(:changed?)

  describe "OracleEnhancedAdapter dirty object tracking" do
    include SchemaSpecHelper

    before(:all) do
      ActiveRecord::Base.establish_connection(CONNECTION_PARAMS)
      schema_define do
        create_table :test_employees, force: true do |t|
          t.string    :first_name,  limit: 20
          t.string    :last_name,   limit: 25
          t.integer   :job_id,      limit: 6, null: true
          t.decimal   :salary,      precision: 8, scale: 2
          t.text      :comments
          t.date      :hire_date
        end
      end

      class TestEmployee < ActiveRecord::Base
      end
    end

    after(:all) do
      schema_define do
        drop_table :test_employees
      end
      Object.send(:remove_const, "TestEmployee")
      ActiveRecord::Base.clear_cache!
    end

    it "should not mark empty string (stored as NULL) as changed when reassigning it" do
      @employee = TestEmployee.create!(first_name: "")
      @employee.first_name = ""
      expect(@employee).not_to be_changed
      @employee.reload
      @employee.first_name = ""
      expect(@employee).not_to be_changed
    end

    it "should not mark empty integer (stored as NULL) as changed when reassigning it" do
      @employee = TestEmployee.create!(job_id: "")
      @employee.job_id = ""
      expect(@employee).not_to be_changed
      @employee.reload
      @employee.job_id = ""
      expect(@employee).not_to be_changed
    end

    it "should not mark empty decimal (stored as NULL) as changed when reassigning it" do
      @employee = TestEmployee.create!(salary: "")
      @employee.salary = ""
      expect(@employee).not_to be_changed
      @employee.reload
      @employee.salary = ""
      expect(@employee).not_to be_changed
    end

    it "should not mark empty text (stored as NULL) as changed when reassigning it" do
      @employee = TestEmployee.create!(comments: nil)
      @employee.comments = nil
      expect(@employee).not_to be_changed
      @employee.reload
      @employee.comments = nil
      expect(@employee).not_to be_changed
    end

    it "should not mark empty text (stored as empty_clob()) as changed when reassigning it" do
      @employee = TestEmployee.create!(comments: "")
      @employee.comments = ""
      expect(@employee).not_to be_changed
      @employee.reload
      @employee.comments = ""
      expect(@employee).not_to be_changed
    end

    it "should mark empty text (stored as empty_clob()) as changed when assigning nil to it" do
      @employee = TestEmployee.create!(comments: "")
      @employee.comments = nil
      expect(@employee).to be_changed
      @employee.reload
      @employee.comments = nil
      expect(@employee).to be_changed
    end

    it "should mark empty text (stored as NULL) as changed when assigning '' to it" do
      @employee = TestEmployee.create!(comments: nil)
      @employee.comments = ""
      expect(@employee).to be_changed
      @employee.reload
      @employee.comments = ""
      expect(@employee).to be_changed
    end

    it "should not mark empty date (stored as NULL) as changed when reassigning it" do
      @employee = TestEmployee.create!(hire_date: "")
      @employee.hire_date = ""
      expect(@employee).not_to be_changed
      @employee.reload
      @employee.hire_date = ""
      expect(@employee).not_to be_changed
    end

    it "should not mark integer as changed when reassigning it" do
      @employee = TestEmployee.new
      @employee.job_id = 0
      expect(@employee.save!).to be_truthy

      expect(@employee).not_to be_changed

      @employee.job_id = "0"
      expect(@employee).not_to be_changed
    end

    it "should not update unchanged CLOBs" do
      @employee = TestEmployee.create!(
          comments: "initial"
      )
      expect(@employee.save!).to be_truthy
      @employee.reload
      expect(@employee.comments).to eq("initial")

      oci_conn = @conn.instance_variable_get("@connection")
      class << oci_conn
         def write_lob(lob, value, is_binary = false); raise "don't do this'"; end
      end
      expect { @employee.save! }.not_to raise_exception(RuntimeError, "don't do this'")
      class << oci_conn
        remove_method :write_lob
      end
    end

    it "should be able to handle attributes which are not backed by a column" do
      TestEmployee.create!(comments: "initial")
      @employee = TestEmployee.select("#{TestEmployee.quoted_table_name}.*, 24 ranking").first
      expect { @employee.ranking = 25 }.to_not raise_error
    end
  end

end