Last time I finished with a failing test case which drove the development to a phase where I had to deal with a sentence instead of a word. The fix was not a big deal, but I ended up with a method in SimpleTextMunger which did three things:

// ...
public String execute(String sentence) {
  StringBuilder mungedSentence = new StringBuilder();
  for (String word : sentence.split(" ")) {
    mungedSentence.append(mungeAWord(word)).append(" ");
  }
  return mungedSentence.toString().trim();
}
 
private String mungeAWord(String word) {
  // ... prior content of the execute(String) method
}

1. convert the sentence into words
2. munge a word
3. collect the munged words and create the new sentence

The first and the third one belong together because they work with a sentence, so I created two classes – SentenceHelper and Munger -, which are used by the SimpleTextMunger:

public class SimpleTextMunger {
  public String execute(String sentence) {
    SentenceHelper sentenceHelper = new SentenceHelper();
    Munger munger = new Munger();
 
    List words = sentenceHelper.split(sentence);
    for (int i = 0; i < words.size(); i++) {
      words.set(i, munger.munge(words.get(i)));
    }
    return sentenceHelper.join(words);
  }
}
 
class Munger {
  public String munge(String word) {
    // the same as before
  }
}
 
class SentenceHelper {
  public List split(String sentence) {
    // ...
  }
 
  public String join(List words) {
    // ...
  }
}

One day, I’d like to write unit tests, mocks – you know, the whole package -, so I must move those two new statements out of the scope of the execute method. Fortunately, I already have spring, so I’m just going to hack a solution together to see whether it works or not. I can do it now, because all the scenarios are green.

This is the best thing about scenarios and BDD, that I can do experimenting, spiking, refactoring or anything else without changing the test cases. Try to do it with unit tests: the moment you move something, the mocks will turn red and you have to do a lot of unnecessary work by fixing them. Read more »