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7. Testing methods of python programming language
Computer science1015 (CSC1015F)
University of Cape Town
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CSC1015F Assignment 7: Testing
Assignment Instructions
This assignment involves constructing tests, assembling automated ‘doctest’ test scripts,
and developing and reasoning about Python programs that use input and output statements,
'if' and 'if-else' control flow statements, 'while' statements, ‘for’ statements, and
statements that perform numerical manipulation.
NOTE Your solutions to this assignment will be evaluated for correctness and for the following qualities: - Documentation o Use of comments at the top of your code to identify program purpose, author and date. o Use of comments within your code to explain each non-obvious functional unit of code. - General style/readability o The use of meaningful names for variables and functions. - Algorithmic qualities o Efficiency, simplicity These criteria will be manually assessed by a tutor and commented upon. In this assignments, up to 10 marks will be deducted for deficiencies.
Question 1 [30 marks]
This question concerns devising a set of tests for a Python function that cumulatively
achieve path coverage.
The Vula page for this assignment provides a Python module called ‘numberutil’ as
an attachment. The module contains a function called ‘aswords’. The function accepts an
integer (0-999) as a parameter and returns the English language equivalent.
For example, aswords(905) returns the string'Nine hundred and five'.
Your task:
Develop a set of 8 test cases that achieve path coverage.
Code your tests as a doctest script suitable for execution within Wing IDE.
Save your doctest script as ‘testnumberutil’.
NOTE : make sure the docstring in your script contains a blank line before the closing “””.
(The automarker requires it.)
NOTE: the aswords() function is believed to be error free.
Question 2 [30 marks]
This question concerns devising a set of tests for a Python function that cumulatively
achieve statement coverage.
The Vula page for this assignment provides a Python module called ‘timeutil’ as an
attachment. The module contains a function called ‘validate’. The purpose of this
function is to accept a string value as a parameter and determine whether it is a valid
representation of a 12 hour clock reading.
The string is a valid representation if the following applies:
- It comprises 1 or 2 leading digits followed by a colon followed by 2 digits followed by a space followed by a two letter suffix.
- The leading digit(s) form an integer value in the range 1 to 12.
- The 2 digits after the colon form an integer value in the range 0 to 59.
- The suffix is ‘a.’ or ‘p.’.
Leading and trailing whitespace is ignored.
1:15 p. 12:59 a.
11:01 p.
Examples of invalid strings:
01:1 a.
21:15 p. 12:61 am
111:01 p.
Your task:
Develop a set of 6 test cases that achieve statement coverage.
Code your tests as a doctest script suitable for execution within Wing IDE (like the
testchecker module described in the appendix).
- Save your doctest script as ‘testtimeutil’.
NOTE : make sure the docstring in your script contains a blank line before the closing “””.
(The automarker requires it.)
NOTE: the validate function is believed to be error free.
Appendix: Testing using the doctest module
The doctest module utilises the convenience of the Python interpreter shell to define, run, and check tests in a repeatable manner. Say, for instance, we have a function called 'check' in a module called 'checker': 1 # checker 2 3 def check(a, b): 4 result= 5 if a<25: 6 result=result+ 7 if b<25: 8 result=result+ 9 return result We've numbered the lines for convenience. The function is supposed to behave as follows: if a is less than 25 then add 1 to the result. If b is less than 25 then add 2 to the result. Possible outcomes are 0, 1, 2, or 3. For the sake of realism, that there's an error in the code. Line 6 should be 'result=result+1'.) Here are a set of tests devised to achieve path coverage: test # Path(lines executed) Inputs (a,b) Expected Output 1 3, 4, 5, 6, 7, 8, 9 (20, 20) 3 2 3, 4, 5, 6, 7, 9 (20, 30) 1 3 3, 4, 5, 7, 8, 9 (30, 20) 2 4 3, 4, 5, 7, 9 (30, 30) 0
Note that we analyse the code to identify paths and select inputs that will cause that path to be followed. Given the inputs for a path, we study the function specification (the description of its intended behaviour) to determine the expected output.
Here is a doctest script for running these tests: >>> import checker >>> checker(20, 20) 3 >>> checker(20, 30) 1 >>> checker(30, 20) 2 >>> checker(30, 30) 0 The text looks much like the transcript of an interactive session in the Python shell. A line beginning with '>>>' is a statement that doctest must execute. If the statement is supposed to produce a result, then the expected value is given on the following line e. 'checker(20, 20)' is expected to produce the value 3. NOTE: there must be a space between a ‘>>>’ and the following statement. It is possible to save the script just as a text file. However, because we're using Wing IDE, it's more convenient to package it up in a Python module (available on the Vula assignment page):
testchecker""" >>> import checker >>> checker(20, 20) 3 >>> checker(20, 30) 1 >>> checker(30, 20) 2 >>> checker(30, 30) 0
""" import doctest doctest(verbose=True) The script is enclosed within a Python docstring. The docstring begins with three double quotation marks and ends with three double quotation marks. NOTE : the blank line before the closing quotation marks is essential. Following the docstring is an instruction to import the doctest module, followed by an
instruction to run the 'testmod()' function. (The parameter 'verbose=True' ensures that the function prints what it's doing.) If we save this as say, 'testchecker', and run it, here's the result: Trying: import checker Expecting nothing ok Trying: checker(20, 20) Expecting: 3
File "testchecker", line 3, in main Failed example: checker(20, 20) Expected: 3 Got: 5 Trying: checker(20, 30) Expecting: 1
File "testchecker", line 5, in main Failed example: checker(20, 30)
0
ok 1 items passed all tests: 5 tests in main 5 tests in 1 items. 5 passed and 0 failed. Test passed.
END
7. Testing methods of python programming language
Course: Computer science1015 (CSC1015F)
University: University of Cape Town
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