RailsCasts中文版，#12 Refactoring User Name Part 3 重构实战3

在重构实战2和重构实战1里，我们讨论了与重构、测试有关的话题。截止上一篇结束时，完成了对User类的重构，但是测试用例代码还有些乱。让我们看看如何清理一下。

require 'test_helper'
  class UserTest < ActiveSupport::TestCase
    test "full name without middle initial" do
      user = User.new(:first_name => "John", :last_name => "Smith")
      assert_equal 'John Smith', user.full_name
    end

    test "full name with middle initial" do
      user = User.new(:first_name => "Paul", :middle_initial => "P", :last_name => "Hughes")
      assert_equal 'Paul P. Hughes', user.full_name
    end

    test "full name with empty middle initial" do
      user = User.new(:first_name => "John", :middle_initial => "", :last_name => "Jones")
      assert_equal 'John Jones', user.full_name
    end
end

User类的测试用例代码。

现在这三个用例，有大量的冗余代码。都是分别创建一个User的对象，然后比较full_name方法的返回值与我们的期待值是否一致。应该创建一个方法，帮我们完成创建对象及返回full_name的结果。

def full_name(first, middle, last)
  User.new(:first_name => first, :middle_initial => middle, :last_name => last).full_name
end

UserTest类中的辅助方法。

这样一来，测试用例代码可以被精简为下面的样子：

test "full name without middle initial" do
  assert_equal "John Smith", full_name('John', nil, 'Smith')
end

test "full name with middle initial" do
  assert_equal 'Paul P. Hughes', full_name('Paul', 'P', 'Hughes')
end  

test "full name with empty middle initial" do
  assert_equal "John Jones", full_name('John', '', 'Jones')
end

简化后的测试代码。

运行之后，所有的用例依然能够通过。

Laa-Laa:ep11 eifion$ autotest
loading autotest/rails
/opt/local/bin/ruby -I.:lib:test -rtest/unit -e "%w[test/unit/user_test.rb test/functional/users_controller_test.rb].each { |f| require f }" | unit_diff -u
Loaded suite -e
Started
...
Finished in 0.282538 seconds.

3 tests, 3 assertions, 0 failures, 0 errors

输出显示用例执行通过。

测试代码变得简单多了，可以把他们移动到一个用例中。但这么做同时带来了一个新的问题，如果某一个测试条件没有满足，怎样识别出来呢？可以再assert_equal方法中多传入一个字符串，测试不通过时会打印出来以便定位。

require 'test_helper'

class UserTest < ActiveSupport::TestCase
  test "full name" do
    assert_equal "John Smith", full_name('John', nil, 'Smith'), 'nil middle initial'
    assert_equal 'Paul P. Hughes', full_name('Paul', 'P', 'Hughes'), 'P middle initial'
    assert_equal "John Jones", full_name('John', '', 'Jones'), 'blank middle initial'
  end

  def full_name(first, middle, last)
    User.new(:first_name => first, :middle_initial => middle, :last_name => last).full_name
  end
end

重构后的UserTest代码

这三篇文章，我们对代码和测试用例都分别进行了重构，代码的可读性和可维护性都得到了提升。好啦！希望这个小例子能让你感受到进行重构和使用测试用例的益处吧！

作者授权：Your welcome to post the translated text on your blog as well if the episode is free(not Pro). I just ask that you post a link back to the original episode on railscasts.com.

原文链接：http://railscasts.com/episodes/12-refactoring-user-name-part-3