Fix TypeError from being raised during creation of RuntimeError

[delirious-lettuce]

I was taking a break from reading this awesome book (EPI in Python) and noticed something while looking through the Python test_framework code.

EPIJudge/epi_judge_python/test_framework/test_utils_deserialization.py

Line 147 in 238ccde

raise RuntimeError("Tuple parser: expected " + str(

>>> parsers = [1, 2, 3]
>>> data = [3, 4, 5, 6, 7]

# Issue
>>> raise RuntimeError("Tuple parser: expected " + str(len(parsers)) + " values, got " + len(data))
Traceback (most recent call last):
  File "<input>", line 1, in <module>
TypeError: must be str, not int

# Cause
>>> " values, got " + len(data)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
TypeError: must be str, not int
>>> "" + 1
Traceback (most recent call last):
  File "<input>", line 1, in <module>
TypeError: must be str, not int

# Solution
>>> raise RuntimeError("Tuple parser: expected {} values, got {}".format(len(parsers), len(data)))
Traceback (most recent call last):
  File "<input>", line 1, in <module>
RuntimeError: Tuple parser: expected 3 values, got 5

[tsunghsienlee]

@delirious-lettuce Do you know which file trigger this error?

[delirious-lettuce]

@tsunghsienlee ,

It wasn't raised from me running any particular file, I was just reading through the source code and it was highlighted in PyCharm so I took a look.

[tsunghsienlee]

@delirious-lettuce I see, and many thanks for this. It seems I shall use some lint tools to find those bugs. Feel free to report anything you find, and I think many future fellow readers would be benefited from this.

[delirious-lettuce]

@tsunghsienlee ,

No problem at all! I will definitely report anything else I find.

I also wanted to say thanks to you and your co-authors. I just found this book from a comment on HackerNews and got it in the mail a few days ago. Having these problems/solutions written in modern Python (3.6!) is so helpful for me!