Unit Tests¶
Warming Up¶
How many words are in the following sentence?¶
:::bash
Call me Ishmael.
How many words are in the next sentence?¶
:::bash
"you haint no objections to sharing a harpooneer's blanket,
have ye? I s'pose you are goin' a-whalin',
so you'd better get used to that sort of thing."
Exercise 1: Test a Python function¶
The function count_words() in the module word_counter.py calculates the number of words in a text body.
For instance, we would expect the following input to result in a word count of 3:
:::bash
Call me Ishmael
Your task is to prove that the count_words() function in fact returns 3.
Run the example test in test_unit_test.py with
:::bash
pytest test_unit_test.py
Exercise 2: A test fails if code is broken¶
Run the tests in test_broken.py and inspect the output.
One of the tests fails, because there is a bug in the function count_words().
The other test fails because there is a bug in the test.
Find out what is broken in which test.
Exercise 3: Fixing tests¶
Fix the code and test in test_broken.py.
Run the tests again, so that both of them pass.
Exercise 4: Test border cases¶
High quality tests cover many different situations. Common situations for the program word_counter.py include:
test case |
description |
example input |
expected output |
|---|---|---|---|
empty |
input is valid, but empty |
"" |
0 |
minimal |
smallest reasonable input |
"whale" |
1 |
typical |
representative input |
"whale eats captain" |
3 |
invalid |
input is supposed to fail |
777 |
|
maximum |
largest reasonable input |
Melville's entire book |
> 200000 |
nasty |
difficult example |
"That #~&%* program still doesn't work!" |
6 |
Your task is to make all tests in test_border_cases.py pass.
Exercise 5: Special characters¶
Add a new feature to the word_counter.py program. The program should remove special characters from the text before counting words.
Your task is to write a test for this new feature.
