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我正在学习 rails（我主要是一名 java 开发人员），这在我的问题中很明显，并且无法从我的 rspec 测试中访问我的模型上的方法。我基本上遵循本教程，但将其应用于我自己的项目。我试图将毕业年份定义为一种基于学生成绩和一年中当前时间的方法。当我实例化对象并在 rails 控制台中调用该方法时，它按我的预期工作，但是当我尝试在测试中这样做时，我得到：

undefined method `graduation_year'

学生.rb

class Student < ActiveRecord::Base
  validates :school_id, presence: true, uniqueness: true
  validates :first_name, presence: true, length: { maximum: 30 }
  validates :last_name, presence: true, length: { maximum: 40 }
  validates :gender, presence: true, inclusion: { :in => %w(m f M F) }
  validates :grade, presence: true, numericality: { greater_than_or_equal_to: 1 , less_than_or_equal_to: 12 }

  def graduation_year
    year = Date.today.year + ( 12 - grade )
  end
end

student_spec.rb

require 'spec_helper'

describe Student do
  before { @student = Student.new(
                        school_id: 3, 
                        first_name: "Michael", 
                        last_name: "Green", 
                        gender: "M", 
                        grade: 6)}

  subject { @student }

  it { should respond_to(:school_id) }
  it { should respond_to(:first_name) }
  it { should respond_to(:last_name) }
  it { should respond_to(:gender) }
  it { should respond_to(:grade) }
  it { should respond_to(:graduation_year) }

  it { should be_valid }

  describe "when school_id is not present" do
    before { @student.school_id = " " }
    it { should_not be_valid }
  end
  .
  .
  .  
  describe "when grade is 7 graduation_year should be calculated correctly" do
    before { @student.grade = 7 }
    expect(@student.graduation_year).to eq(Date.today.year+5)
  end
end

错误信息

~/dev/rails_apps/spec/models/student_spec.rb:96:in `block (2 levels) in <top (required)>': undefined method `graduation_year' for nil:NilClass (NoMethodError)
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/example_group.rb:242:in `module_eval'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/example_group.rb:242:in `subclass'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/example_group.rb:228:in `describe'
from ~/dev/rails_apps/spec/models/student_spec.rb:94:in `block in <top (required)>'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/example_group.rb:242:in `module_eval'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/example_group.rb:242:in `subclass'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/example_group.rb:228:in `describe'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/dsl.rb:18:in `describe'
from ~/dev/rails_apps/spec/models/student_spec.rb:3:in `<top (required)>'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `load'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `block in load_spec_files'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `each'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/configuration.rb:819:in `load_spec_files'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/command_line.rb:22:in `run'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/runner.rb:80:in `run'
from ~/dev/.rvm/gems/ruby-2.0.0-p247/gems/rspec-core-2.13.1/lib/rspec/core/runner.rb:17:in `block in autorun'

另外，我不认为这是问题所在，但我最初graduation_year在 Student 表上有一个属性，但删除了它，这个测试应该验证它的计算是否正确。

我也在puts first_name测试中尝试过，我得到了相同的未定义方法错误，但是在first_name. 我想我只是错过了关于 ruby​​/rails 工作方式的一些东西。

4

2 回答 2

2

您的期望语句未包含在“it”子句中。尝试写作

describe "when grade is 7" do
  before { @student.grade = 7 }
  it 'calculates the graduation year correctly' do
    expect(@student.graduation_year).to eq(Date.today.year+5)
  end
end

作为旁注，以这种方式使用@student 不是惯用的。你最好使用一个定义student的let语句。因此，您可以编写如下内容，而不是使用 Student.new 的初始 before 块：

let(:student) { Student.new(
                    school_id: 3, 
                    first_name: "Michael", 
                    last_name: "Green", 
                    gender: "M", 
                    grade: 6)}

并且您随后对“@student”的所有引用都将替换为“student”。这样可以确保没有任何内容泄漏到描述块中（或泄漏）。

let 语句将记住该对象，并且仅在规范中引用了 student 时才实例化该对象。

于 2013-10-15T01:42:57.757 回答
1

您不能describe像您的行那样直接在块内设置期望：

expect(@student.graduation_year).to eq(Date.today.year+5)

你没有说你得到了什么具体的错误（即什么对象有未定义的方法），但由于所有未定义的实例变量都是，所以它@student不会有方法。但是，如果它是一个有效的表达式，您将在调用中获得一个未定义的方法。nilnilgraduation_year@student.graduation_yearexpect

于 2013-10-14T23:24:03.517 回答