Book Image

The Python Apprentice

By : Robert Smallshire, Austin Bingham
Book Image

The Python Apprentice

By: Robert Smallshire, Austin Bingham

Overview of this book

Experienced programmers want to know how to enhance their craft and we want to help them start as apprentices with Python. We know that before mastering Python you need to learn the culture and the tools to become a productive member of any Python project. Our goal with this book is to give you a practical and thorough introduction to Python programming, providing you with the insight and technical craftsmanship you need to be a productive member of any Python project. Python is a big language, and it’s not our intention with this book to cover everything there is to know. We just want to make sure that you, as the developer, know the tools, basic idioms and of course the ins and outs of the language, the standard library and other modules to be able to jump into most projects.
Table of Contents (21 chapters)
Title Page
Credits
About the Authors
www.PacktPub.com
Customer Feedback
Preface
12
Afterword – Just the Beginning

Testing for file existence


Finally, we can see one more very useful type of assertion by writing a test to verify that analyze_text() doesn't delete the file — a reasonable requirement for the function!:

# text_analyzer.py

class TextAnalysisTests(unittest.TestCase):
    . . .
    def test_no_deletion(self):
        "Check that the function doesn't delete the input file."
        analyze_text(self.filename)
        self.assertTrue(os.path.exists(self.filename))

The TestCase.assertTrue() function simply checks that the value passed to it evaluates to True. There is an equivalent assertFalse() which does the same test for false values.

As you probably expect, this test passes already as well:

% python text_analyzer.py
.....
----------------------------------------------------------------------
Ran 5 tests in 0.002s

OK

So now we've got a useful, passing set of tests! This example is small, but it demonstrates many of the important parts of the unittest module. There are many more parts to the unittest...