Python Unit Test Automation

Figure 6-1.  TDD flow
To see how TDD is implemented in Python with pytest, create a directory called 
chapter06 for this TDD in the code directory. You will use this directory for the TDD 
exercise.

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Create the test module shown in Listing 
6-1
 in the chapter06 directory.
Listing 6-1.  test_module01.py
class TestClass01:
        def test_case01(self):
               calc = Calculator()
               result = calc.add(2, 2)
               assert 4 == result
Run the code in Listing 
6-1
 with the following command:
py.test -vs test_module01.py
The output will be as follows:
============================= test session starts =============================
platform linux -- Python 3.4.2, pytest-3.0.4, py-1.4.31, pluggy-0.4.0 -- /
usr/bin/python3
cachedir: .cache
rootdir: /home/pi/book/code/chapter06, inifile:
collected 1 items
test_module01.py::TestClass01::test_case01 FAILED
================================== FAILURES ===================================
___________________________ TestClass01.test_case01 ___________________________
self =
    def test_case01(self):
>           calc = Calculator()
E           NameError: name 'Calculator' is not defined
test_module01.py:4: NameError
=========================== 1 failed in 0.29 seconds ==========================
From this output, you can see that the problem is due to us not importing 
Calculator. That is because we have not created the Calculator module yet! So let’s 
define the Calculator module in a file called calculator.py, as shown in Listing 
6-2
, 
under the same directory,

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Chapter 6 
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 tips and triCks
104