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HW2: Improving Coverage
Due Monday by 11:59pm Points 15 Submitting on paper
Introduction
Last week, you applied black box testing techniques. This meant that you had no
week, you will apply white box testing techniques. Therefore, I am providing you with the code you
will be testing. Also, since white box testing doesn't care about the specification, the function under
test is purely contrived and serves no purpose! Well, that isn't entirely true, the purpose is to give
you an opportunity to flex your coverage muscles, but it doesn't do anything.
Course Learning Outcome(s):
Apply testing techniques, including black-box and white-box techniques, automatic testing
activities, and regression testing (CLO 4)
Module Learning Outcome(s):
Apply white box testing techniques
Description
For this assignment you will have to achieve 100% Branch and Condition Coverage. For this
assignment, this means that for each conditional statement, you need to have a test case for each
combination of conditions. So if your conditional statement was a or b you would need to have a
test case for each row of the following truth table:
a b outcome
T T T
T F T
F T T
F F F
If you recall what I said in the exploration, Branch and Condition coverage is usually not done due
to the number of tests required. The reason we are doing it here, is we are only testing a single
function, not an entire program. The function under test is defined below.
Behold! The Source!
def contrived_func(val):
# This function serves no logical purpose
# DO NOT try to make sense of it!
# Just make sure your tests cover everything requested
# val is a numerical value
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if val < 150 and val > 100:
return True
elif val * 5 < 361 and val / 2 < 24:
if val == 6:
return False
else:
return True
elif (val > 75 or val / 8 < 10) and val**val % 5 == 0:
return True
else:
return False
Again, this function's only purpose is as a learning aid, it doesn't do anything. DO NOT try to
rationalize its behavior! This function is contained within contrived_func.py , so make sure you are
importing the correct file.
You need to write a series of unit tests that attempt to meet 100% Branch and Condition Coverage.
Once submitted to Gradescope, the autograder will run the tests against a modified version of the
above code. The contrived_func on Gradescope is functionally equivalent but includes print
statements when each condition combination is triggered. There are 12 such triggers, labled C1-
C12. You will only receive full credit for the autograded portion if your test suite triggers all 12
print statements.
Outside of the autograded portion, your test suite will also be graded based on how many tests
were required to uncover all 12 triggers. Full points will only be rewarded if you can do it with 7 or
fewer test cases. Please note, that if your tests do not pass the autograder with full marks, you will
not be eligible for these Efficient Testing points. Also, for the purposes of the efficiency points,
each assert counts as a single test, so no putting in multiple asserts in each test case.
Finally, as was the case last week, your test suite needs to be free of linting errors.
Hints
Truth Tables
I highly recommend you write out, by hand, the truth tables for each conditional statement. I believe
in this so much I have provided you with the truth table for the first conditional below. Notice that
the third row has T for the second condition. This is because the conditions are linked by and ,
which means if the first condition is false, then the second one does not execute. This makes the
third and fourth rows logically equivalent, so there is no need to write a test case for the fourth row
(it is also impossible for both conditions to be False at the same time).
val < 150 val > 100 outcome Condition Label
T T T C1
T F F C2
F T F C3
F F F C3
PyCharm Tools
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PyCharm includes tools to track statement and branch coverage. These need to be enabled and/or
installed. You can do this by going to your project settings and searching for "Coverage", which is
found under "Build, Execute, Deployment". Where it says "When new coverage is gathered" ensure
"Activate Coverage View" is checked. Also, if you want to examine branch coverage, ensure that it
is checked under "Python coverage"
You can then right-click on your testing file and select "Run...with Coverage". If this is the first time
you have run with coverage, PyCharm may prompt you at the bottom to install the coverage
module. You can do so simply by clicking "install" in the prompt.
Once run, it will open up a new panel where you can see the statement coverage for each file. You
can also look in the "gutter" to see which lines haven't been executed. In case you are not familiar,
the gutter is the area to the left of the code that you can put breakpoints and often contains the line
numbers.
Lines that are marked in red haven't been executed and those marked in yellow indicate branches
that haven't been triggered.
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Some Rubric
To see which branch hasn't executed, left-click on the yellow in the gutter. You will be told that the
line "was hit", but which line wasn't jumped to (i.e. the branch).
Unfortunately, there is no way for PyCharm to track condition coverage, so you will have to rely on
Misc
You will need to include
if __name__ == '__main__':
unittest.main()
Feel free to take the provided source above and create your own contrived_func.py to run your
tests against to help find errors with your testing file
Do not use Random Testing for this assignment, you will get your chance in HW3: Random
Testing Hands On
What to turn in