factory_girl_railsで生成したオブジェクトを破壊的メソッドで変更する場合の注意点 ref: http://qiita.com/t_oginogin/items/e5bd1e452d0c4ab714e1

file2.txt

$ bundle exec rake test
Run options: --seed 59117

# Running tests:

[index]report no:R00002
[index]report no:R00003
[index]report no:R00004
[index]report no:R00005
[index]report no:R00006
[index]report no:R00007
[index]report no:R00008
[index]report no:R00009
[index]report no:R00010
[index]report no:R00011
.[show]report no:R00011 // ここはR00001を期待していた
F

Finished tests in 0.097491s, 20.5147 tests/s, 20.5147 assertions/s.

  1) Failure:
ReportsController::show#test_0001_指定したレポートを取得できる [/Users/xxx/test_app/test/controllers/reports_controller_test.rb:29]:
Expected: "R00001"
  Actual: "R00011"

file3.txt

report_no = FactoryGirl.build(:report_test1).report_no.dup

file4.txt

$ be rake test
Run options: --seed 21061

# Running tests:

[index]report no:R00002
[index]report no:R00003
[index]report no:R00004
[index]report no:R00005
[index]report no:R00006
[index]report no:R00007
[index]report no:R00008
[index]report no:R00009
[index]report no:R00010
[index]report no:R00011
.[show]report no:R00001
.

Finished tests in 0.089792s, 22.2737 tests/s, 22.2737 assertions/s.

2 tests, 2 assertions, 0 failures, 0 errors, 0 skips

reports.rb

FactoryGirl.define do
  factory :report_test1, class: :Report do
    report_no 'R00001'
    title 'report title'
    content 'report content'
  end
end

reports_controller_test.rb

require 'test_helper'

describe ReportsController do
  describe "index" do
    before do
      report_no = FactoryGirl.build(:report_test1).report_no
      10.times do
        report = FactoryGirl.build(:report_test1)
        report.report_no = report_no.succ! #破壊的メソッドでインクリメント
        puts "[index]report no:#{report.report_no}"
        report.save
      end
    end

    it "10件のデータを取得できる" do
      get :index
      assert_equal 10, assigns(:reports).count
    end
  end

  describe "show" do
    before do
      report = FactoryGirl.create(:report_test1)
      puts "[show]report no:#{report.report_no}"
    end

    it "指定したレポートを取得できる" do
      get :show, id: 1

      assert_equal 'R00001', assigns(:report).report_no
    end

  end
end