# RSpec can't define singleton error when trying to mock gets and puts for Hash Elements

**URL:** <https://www.ruby-forum.com/t/rspec-cant-define-singleton-error-when-trying-to-mock-gets-and-puts-for-hash-elements/245878>\
**Category:** RSpec\
**Created:** [July 20, 2013, 11:50am UTC](https://www.ruby-forum.com/t/rspec-cant-define-singleton-error-when-trying-to-mock-gets-and-puts-for-hash-elements/245878 "2013-07-20T11:50:21Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Sadaf\_N](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@Sadaf\_N](https://www.ruby-forum.com/u/Sadaf_N)\
**Post date:** [July 20, 2013, 11:50am UTC](https://www.ruby-forum.com/t/rspec-cant-define-singleton-error-when-trying-to-mock-gets-and-puts-for-hash-elements/245878/1 "2013-07-20T11:50:21Z")

</div>

I have a Book Model which is a ruby script that assigns prices to  
certain predefined Book titles mentioned in the program. Here’s how the  
book model looks:-

```
class Book

  attr_accessor :books
  def initialize books
    puts "Welcome to setting book price program"
    @books = books
  end

  def get_prices
    puts "Please enter appropriate price for each book item:-"
    count = 0
    @books = @books.inject({}) { |hash, book|
      print "#{book.first}: "
      price = STDIN.gets.chomp
      while (price !~ /^[1-9]\d*$/ && price != "second hand")
        puts "Price can't be 0 or a negative integer or in decimal

```

format or alphanumeric. \nPlease input appropriate price in integer"  
price = STDIN.gets.chomp #gets.chomp - throws error  
end  
price == “second hand” ? price = “100” : price #takes a  
default price  
hash[book.first] = price.to\_i  
hash  
}  
end

```
end

books = {"The Last Samurai" => nil,
         "Ruby Cookbook" => nil,
         "Rails Recipes" => nil,
         "Agile Development with Rails" => nil,
         "Harry Potter and the Deathly Hallows" => nil}

book_details = Book.new(books)
book_details.get_prices
puts "\n *******Books Details:#{book_details.books}****** \n"

```

I’m trying to write a test case that checks for correct input of price  
for each book item. If the price is entered inappropriately, it should  
ask the user to re enter the price correctly. The program does this  
fine. But I’m facing difficulties when I’m trying to mock this behavior  
using RSpec.

```
require 'spec_helper'

describe Book do

  before :each do
    books = {"The Last Samurai" => nil,
         "Ruby Cookbook" => nil,
         "Rails Recipes" => nil,
         "Agile Development with Rails" => nil,
         "Harry Potter and the Deathly Hallows" => nil}
    @book = Book.new(books)
  end

  describe "#new" do
    it "Should be an instance of the Book" do
      @book.should be_an_instance_of Book
    end
  end

  describe "#getprice" do
    it "Should get the price in the correct format or else return

```

appropriate error" do  
puts  
“\n\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\n”  
book\_obj = @book  
STDOUT.should\_receive(:puts).and\_return(“Welcome to setting  
book price program”)  
book\_obj.get\_prices.should\_not be\_nil  
book\_obj.books[“The Last Samurai”].stub!(:gets) {“40”} #trying  
to set the value for one book using Hash  
book\_obj.books[“The Last Samurai”].should == 40 #verifying the  
value set for a particular key is accurate  
end  
end

```
end

```

You can even clone this code([GitHub - boddhisattva/book: Sample Ruby project - experimenting Ruby with RSpec](https://github.com/boddhisattva/book)) from  
Github to try this from your end. I’m using Ruby 1.9.3 and rspec 2.11.0.  
I’ve also attached all the required ruby scripts in this forum post to  
test this.

```
The error that I'm getting currently is:-

Failures:

  1) Book#getprice Should get the price in the correct format or

```

else return appropriate error  
Failure/Error: book\_obj.books[“The Last Samurai”].stub!(:gets)  
{“40”} #trying to set the value for one book using Hash  
TypeError:  
can’t define singleton  
# ./spec/book\_spec.rb:31:in `block (3 levels) in \<top  
(required)\>’

```
Finished in 7.61 seconds
2 examples, 1 failure

Failed examples:

rspec ./spec/book_spec.rb:21 # Book#getprice Should get the price in

```

the correct format or else return appropriate error

I would really appreciate any guidance how to get this right. Thank you.