Also, it says in the instructions that "Each number will....consist of only the digits 0-9" The unknown number cannot be a negative. -1 should be thought of as Out Of Bounds.

The method takes a string as a paramater repressenting the expression and will return an int value representing the unknown rune or -1 if no such rune exists.

It expects -1 because there is no such rune that satisfy the equality.

I manage to create a specific test case so that you cannot create a huge string that concatenate calls to getChunk().
Now go ahead and try :)

Hello,

I think this is gonna help you because I don't clearly understand your problem (and the jsbin code is evolving):

 test3:
  {
    text: "Once upon a time.\n",
    words: 4,
    chars: 17,
    lines: 2
  },
  test4:
  {
    text: "",
    words: 0,
    chars: 0,
    lines: 0
  },

There is currently no test were the text is only "\n". (Although I might add one because my implementation would failed in that case!).

I guess there is someting wrong in your implementation, likely regarding the word count.

One important thing: you broke one rule in your implementation: "You cannot concatenete calls to getChunk."
It's hard for me to test that, maybe I'll with a huge string which cannot fit in memory.
Please respect that rule, which is the very goal of this exercice: parse by chunks!

I'll try to provide another object to bypass the "Reader is not defined" issue without breaking existing tests.