Rspec test case for array method

Question

I am a fairly new to programming (3 months in), and am attempting to learn via TDD.

Obviously the point to TDD is write the test cases first, this particular piece I wasn't sure how to.

The code snippet is:

class PhraseFactory
  def initialize
    @sentence = ''
  end
  def make_sentences_from
    for i in 0 ... self.length
      @sentence += self[i] + ' '
    end
  end

How I was thinking to test it was using:

describe "When sent a message(<< is that proper terminology?) from an array of strings"
  it "Builds a sentence"
    my_word_array.should_have (here is where I am unclear)sent_a_message_to(make_sentences_from)

Thanks for any help.

phoet · Accepted Answer · 2012-07-03 16:51:41Z

3

i like TDD but i would not recommend anyone to use TDD to learn something new! it's always a good idea to use the REPL (irb) to experiment with code.

your example is full of WTFs for any ruby developer:

you are missing all the ENDs (looks kinda like python?!)
you are naming something Factory (are you a java guy?)
you use for instead of each
you are doing stuff in a class that should be a oneliner
you reinvent the wheel by rebuilding core functionality

besides that, i don't really understand your question and code...

what should the result of your code be? what is the input to your "factory"

$ irb
> %(you can just use join to build a sentence from an array of words).join
"you can just use join to build a sentence from an array of words"

answered Jul 3, 2012 at 16:51

phoet

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2 Comments

Discorick Over a year ago

Sorry about the missing ends, noob omission. The class name is a fluke, I just called it that cause of its function. The for instead of each was me playing with code I found in the ruby pickaxe book. I realize the code is all redundant, I am just trying to cement the basics. The input for factory is (supposed to be) something like sentence = this_array_of_strings.make_sentence_from

Discorick Over a year ago

It also just occurred to me... in order for this to work I suppose it would be necessary to make my method an extension of the Array class, not a class of its own? Otherwise I would have to new it up everytime?

Mathias · Accepted Answer · 2012-07-03 17:15:45Z

1

Learning both a new language (Ruby) and technique (TDD) at once may be a bit too much. On the other hand, I find unit tests a great way to clarify code behavior, and as such a good learning tool. One suggestion here would be to look into something like the Ruby Koans: http://rubykoans.com/

I am not a Rubyist, so I can't comment on their quality, but I used the F# Koans, which were adapted from the Ruby ones, and were pretty good. This should both give you a good entry point into the language, as well as a familiarity with unit testing, which should serve you well once you start working on your own project and get into TDD.

answered Jul 3, 2012 at 17:15

Mathias

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