我想根据外部数据源动态生成一系列规范。具体来说，我下载了一个 Google 电子表格，电子表格中的每一行都应该用于其自己的测试用例:

describe "Cases" do
  before(:all) do
    # Download spreadsheet and
    # populate cases in DB
  end

  Cases.each do |case|
    it "Case #{case.num}" do
      # spec
    end
  end
end

这是行不通的，因为对于使用 RSpec 的初学者来说，(据我所知)不会在编译时“看到”任何规范，所以 before(:all) 永远不会执行。如果我要放置一个空的 it block ，它会让 before(:all) 执行，但是我会遇到 Cases 的问题.each 在其他任何东西之前被求值，它是空的，因为它还没有被 before(:all) block 填充。

简而言之，我很困惑，我对 RSpec 的理解似乎非常有限。我想获取数据，使用该数据设置一堆规范，然后让它们由 RSpec 运行。如果 Cases 是预先设置的数组(在 describe block 之外)，这将(可能？)起作用，但我需要在运行时设置它。我想在 RSpec 中做什么？

最佳答案

This doesn't work, because ... RSpec doesn't ... 'see' any specs at compile-time ...

我想知道为什么，并做了一些研究。如果您检查以下代码和输出，您可以得出一些结论:

• Ruby 中没有编译时间
• 立即评估和执行类/模块的主体
• describe 方法也是如此
• describe block 的主体由 RSpec 立即处理
• RSpec 存储 before block 和 it block 供以后执行
• 当文件解析结束时，RSpec 开始报告 描述字符串并执行存储的before/it示例 block

下面的代码演示了这一点。

module SO
    puts '>>>>> Ruby sees module SO and executes/evaluates its body'
    cases = [1,2,3]

    describe "SO Cases" do
        puts "in module SO, RSpec sees describe Cases self=#{self}"
        before(:each) do
            puts '  in before(:all)'
        end

        cases.each do |case_|
            puts "    in each loop with case_=#{case_}"
            it "Case #{case_}" do
                puts "        check spec for case #{case_}"
            end
        end
    end
end

module M # to avoid "warning: class variable access from toplevel"
    puts '>>>>> Ruby sees module M and executes/evaluates its body'
    describe "M Cases" do
        puts "in module M, RSpec sees describe Cases self=#{self}, ancestors :"
        ancestors.each {|a| puts "    #{a}"}
        print 'self.methods.grep(/^it/) : '; p self.methods.grep(/^it/).sort
        before(:all) do
            puts "  in before(:all) self=#{self}"
            @@cases = [1,2,3]
            puts "  ... now cases=#{@@cases}"
            File.open('generated_cases.rb', 'w') do |fgen|
                fgen.puts 'puts "\n*** inside generated_cases.rb ***"'
                fgen.puts 'module GenSpecs'
                fgen.puts "puts '>>>>> Ruby sees module GenSpecs and executes/evaluates its body'"
                fgen.puts '    describe "GenSpecs Cases" do'
                fgen.puts '        puts "in module GenSpecs, RSpec sees describe Cases"'
                @@cases.each do |case_|
                    puts "    in each loop with case_=#{case_}"
                    fgen.puts <<-IT_SPECS
        it "Case #{case_}" do
            puts "    some spec for case_=#{case_}"
        end
        IT_SPECS
                end
                fgen.puts '    end'
                fgen.puts 'end # module GenSpecs'
                fgen.puts "puts '>>>>> end of ruby file generated_cases.rb <<<<<'"
            end
            puts 'file generated_cases.rb has been closed'
            require_relative 'generated_cases'
        end

        it 'has loaded Cases' do
            @@cases.should_not be_empty
        end
    end
end
puts '>>>>> end of ruby file t2_spec.rb <<<<<'

执行:

$ ruby -v
ruby 1.9.2p320 (2012-04-20 revision 35421) [x86_64-darwin12.2.0]
$ rspec --version
2.12.2
$ rspec --format nested t2_spec.rb 
>>>>> Ruby sees module SO and executes/evaluates its body
in module SO, RSpec sees describe Cases self=#<Class:0x007fcaf49a6e80>
    in each loop with case_=1
    in each loop with case_=2
    in each loop with case_=3
>>>>> Ruby sees module M and executes/evaluates its body
in module M, RSpec sees describe Cases self=#<Class:0x007fcaf2852e28>, ancestors :
    #<Class:0x007fcaf2852e28>
    RSpec::Core::ExampleGroup
    ...
self.methods.grep(/^it/) : [:it, :it_behaves_like, :it_should_behave_like, :its]
>>>>> end of ruby file t2_spec.rb <<<<<

SO Cases
  in before(:all)
        check spec for case 1
  Case 1
  in before(:all)
        check spec for case 2
  Case 2
  in before(:all)
        check spec for case 3
  Case 3

M Cases
  in before(:all) self=#<RSpec::Core::ExampleGroup::Nested_2:0x007fcaf2836ca0>
  ... now cases=[1, 2, 3]
    in each loop with case_=1
    in each loop with case_=2
    in each loop with case_=3
file generated_cases.rb has been closed

*** inside generated_cases.rb ***
>>>>> Ruby sees module GenSpecs and executes/evaluates its body
in module GenSpecs, RSpec sees describe Cases
>>>>> end of ruby file generated_cases.rb <<<<<
  has loaded Cases

GenSpecs Cases
    some spec for case_=1
  Case 1
    some spec for case_=2
  Case 2
    some spec for case_=3
  Case 3

Finished in 0.01699 seconds
7 examples, 0 failures

以这种方式创建文件并要求它是为了演示，可能不适用于您的情况。我建议分两个阶段进行:首先阅读电子表格并创建一个包含 describe 和几个 it 示例的 file.rb。在第二阶段，您启动 Ruby 来处理生成的文件。

关于ruby - 动态 RSpec 规范生成，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/14522131/