带有 RSpec NoMethodError 的 Ruby：nil:NilClass 的未定义方法长度

Question

我是 Ruby 和 RSpec 的新手，试图为字符串长度编写一个单位大小写。我有3个rb文件如下 1.调用文件

require_relative 'ruby_final_operations'
require_relative 'ruby_helper'
require 'uri'
require 'open-uri'
require 'prime'
module RubyOperations
 # Public: Various commands for the user to interact with RubyCommand.
  class Command
    res = RubyOperations::Operations.new
res.letter_count(res.inputstr)

第二个文件 - 方法实现

    require_relative 'ruby_helper'
require 'logger'
$FILE_LOG = RubyOperations.create_log(File.expand_path('~/RubyOperations_LOG.log'), Logger::DEBUG)
$STD_LOG = RubyOperations.create_log(nil, Logger::INFO)
module RubyOperations
class Operations

def inputstr
      RubyOperations.log('Enter the String:[Length 20]',:BOTH)
      @str = gets.chomp
      raise StandardError if @str =~ /\d/ || @str.empty? || @str.length > 20
    rescue StandardError,ArgumentError => e
      RubyOperations.log(e,:ERROR)
    end

def letter_count(str)
    result = @str.length
      RubyOperations.log("The number of letters in the string: #{result}",:BOTH)
end

第三个文件 - RSpec

require 'ruby_final_operations'

describe 'RubyOperations' do
  describe 'Operations' do
   subject = RubyOperations::Operations.new
describe '.letter_count' do
     context 'when operation is provided' do
      it 'returns letter count' do
        allow(subject.letter_count("hello").to receive(:result).and_return(5)
      end
    end
   end

问题在于，在第二个文件中，他的参数是“str”，但存储的键入字符串是“@str”。 如何从 rspec 文件中传递字符串 'hello' 来测试它。

Answer 1

有几个问题：

使用未使用的参数调用 instance_method

def letter_count #get rid of argument, the argument does nothing, 
                 #basically it looks you added the argument, 
                 # just, so you can call the other method there.

让你的主要内容简单，顺序清晰

res.inputstr
res.letter_count

但是关于你的实际问题，在你的测试中你用错误的方法改变了错误的东西

allow(subject.letter_count("hello").to receive(:result).and_return(5)
# letter count should do the log entry, not return five, at least that what your method say

所以你可能想在测试 letter_count 方法之前设置@str。

 subject.instance_variable_set("hello")
 # then test for what you expect the method to return
 expect(subject.letter_count).to eq(5)
 # this specific test will fail, because you are doing a log entry, and not return the length on letter_count.