Re: [Tutor] Do not understand why I am getting "EOFError: EOF when reading a line".

[Walter Prins]

Hi

On 8 October 2016 at 05:51, boB Stepp  wrote:
> I think I now understand why I am getting this EOF exception.
>
> On Fri, Oct 7, 2016 at 10:16 PM, boB Stepp  wrote:
>> My current get_input() function:
>>
>> ==
>> def get_input():
>> '''Get string input from the user and convert it to an integer.  This
>> integer is returned to the caller.
>>
>> :num_sides:  Number of sides for the displayed grid.'''
>>
>> while True:
>> try:
>> num_sides = int(input("Number of sides = "))
>> return num_sides
>> except ValueError:
>> print("'Number of sides' must be a positive integer.  Please 
>> enter "
>> "an integer.")
>> ===
>
> Since the try/except is within a while loop, the input tries to read
> more input after the ValueError occurs.  Of course, I don't have any
> more input strings stored in the StringIO buffer, so it sees this as
> an end of file condition.
>
> But now I do not see how to test get_input() to check for the
> ValueError.  Any suggestions?

Your test is written such that it checks/expect ValueError to be
thrown from get_input().  However, you're in fact catching/trapping
ValueError inside get_input() so it's never going to be seen by the
test.

You cannot have it both ways.  Either your intention is that
get_input() must raise ValueError as your test expects it (and
therefore get_input() shouldn't be [responsible for] catching,
printing and looping as it currently is), or it must not (and should
keep trying until it successfully reads an int).  If the latter is the
case your test needs to change to reflect this reality (by e.g.
perhaps altering what's in the StringIO() input for example, so that
there is a valid in in the input in addition to the invalid 'a', to
allow the loop to terminate.  Then the test should simply check that
get_input() successfully "ignores"/skips over the invalid input and
retrieves that latter integer from the test "input stream" [e.g. what
you put into the StringIO()] and not expect an exception to be
raised.)

Walter
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[Tutor] Python Shell

[Alan Clarke]

Hi.

I have just installed Python 2.7.12 ( i have windows xp).

I created a program called HW.py  that runs under a command prompt, but Python 
Shell gives the following error:

Traceback (most recent call last):
  File "", line 1, in 
HW.py
NameError: name 'HW' is not defined

Can someone please tell me what I'm doing wrong?

I have added the Python directory to the Path.



Alan.
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[Tutor] Accessing Yahoo with Python?

[Jim Byrnes]

I realize that my question is not about the standard library. The only 
reason I am asking here is, if I remember correctly, a regular 
contributor, Danny Yoo, works at Yahoo. I am hoping he, or someone else 
here can help me understand what is happening.


I am writing a program using the yahoo_finance module. Over the past 
week I have been testing and refining it. At first the only errors I was 
seeing were mine.  Lately I have been a lot of these errors.


Traceback (most recent call last):
  File 
"/usr/local/lib/python3.4/dist-packages/yahoo_finance/__init__.py", line 
120, in _request

_, results = response['query']['results'].popitem()
KeyError: 'query'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/jfb/MyProgs/StockHistory/stock_history_oop.py", line 75, 
in 

Stocks().run()
  File "/home/jfb/MyProgs/StockHistory/stock_history_oop.py", line 38, 
in run

self.get_stock_info()
  File "/home/jfb/MyProgs/StockHistory/stock_history_oop.py", line 53, 
in get_stock_info

yahoo = Share(stk)
  File 
"/usr/local/lib/python3.4/dist-packages/yahoo_finance/__init__.py", line 
178, in __init__

self.refresh()
  File 
"/usr/local/lib/python3.4/dist-packages/yahoo_finance/__init__.py", line 
142, in refresh

self.data_set = self._fetch()
  File 
"/usr/local/lib/python3.4/dist-packages/yahoo_finance/__init__.py", line 
181, in _fetch

data = super(Share, self)._fetch()
  File 
"/usr/local/lib/python3.4/dist-packages/yahoo_finance/__init__.py", line 
134, in _fetch

data = self._request(query)
  File 
"/usr/local/lib/python3.4/dist-packages/yahoo_finance/__init__.py", line 
123, in _request

raise YQLQueryError(response['error']['description'])
yahoo_finance.YQLQueryError: Query failed with error: "'No definition 
found for Table yahoo.finance.quotes'".


It has gotten to the point where if I run the program 10 times, 9 of 
them will return the above error before I get the data I want. The part 
of my program that retrieves the data from Yahoo has not changed in 
quite a while.


Is it possible that I have exceeded a Yahoo limit on requests from one 
IP address?  Test data I am using gets the historical info on 3 stocks 
over a 3 day period.


Thanks,  Jim

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Re: [Tutor] TDD: How to test input()?

[Alan Gauld via Tutor]

On 08/10/16 07:18, Steven D'Aprano wrote:

> Testing code that depends on user input is always tricky. There are a 
> few ways to deal with it:
> 
> (5) Or you could manually monkey-patch sys.stdin as you do.

A variation on this that I have used is to read the input
from stdin as usual but redirect stdin when you run the
code:

python test_input.py < testdata.txt

That way I can use multiple sets of test data and run
the tests using the different data sets. The test suite
is then exercised by a simple shell script that runs
against each test file in turn.

I find that easier and more flexible than using a
StringIO buffer. You can catch EOF errors in your
test rig or write the tests to read a finite set
of data and create the data to match.

-- 
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos


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Re: [Tutor] TDD: How to test input()?

[Steven D'Aprano]

On Fri, Oct 07, 2016 at 08:26:28PM -0500, boB Stepp wrote:
> I think I have this figured out, but I want to be certain I am doing
> it both correctly and in the preferred way.  I have a need for a
> get_input() function and have written my first test for this function
> as follows:

Testing code that depends on user input is always tricky. There are a 
few ways to deal with it:

(1) Denial. Just don't test that part of your code at all. That's not 
ideal, but it may be "good enough" if any error in that code would be 
obvious enough.

(2) Perform ad hoc non-automated tests that require user intavention. 
That's a bit better but still not great.

(3) You can monkey-patch the input() function in your test:

import mymodule  # module being tested

class MyTests(unittest.TestCase):
def test_get_input(self):

   def myinput(prompt):
   return "5"

mymodule.input = myinput
try:
result = mymodule.get_input("What number do you want?")
self.assertEqual(result, 5)
finally:
del mymodule.input


That's often a good solution for simple testing.

(4) Python 3 unittest library now includes support for mocking:

https://docs.python.org/3/library/unittest.mock.html


which lets you replace parts of your code with fake code ("mocks") which 
are more easily tested, similar to the monkey-patch example in (3) 
above. For an example, look at the test suite for the "code" module:

https://docs.python.org/3/library/code.html

https://hg.python.org/cpython/file/3.5/Lib/test/test_code_module.py


(5) Or you could manually monkey-patch sys.stdin as you do.


I haven't studied your code in detail to comment on it yet. Time 
permitting, I shall do so later.



-- 
Steve
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