Test-Driven Python Development电子书

Test-Driven Python Development

Table of Contents

Test-Driven Python Development

Credits

About the Author

Acknowledgments

About the Reviewers

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Free access for Packt account holders

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Downloading the example code

Errata

Piracy

Questions

1. Getting Started with Test-Driven Development

Prerequisites

Understanding test-driven development

TDD versus unit testing versus integration testing

Using TDD to build a stock alert application

Writing our first test

Analyzing the test output

Test errors versus test failures

Making the test pass

Reorganizing the test code

Running the tests after the reorganization

Summary

2. Red-Green-Refactor – The TDD Cycle

Tests are executable requirements

Arrange-Act-Assert

Documenting our tests

Testing for exceptions

Exploring assert methods

Specific asserts versus generic asserts

Setup and teardown

Brittle tests

Refactoring the design

Refactoring tests

Exploring the Rule classes

Exercise

Summary

3. Code Smells and Refactoring

A dual crossover moving average

Implementing the dual crossover moving average

Identifying code smells

Refactoring

The Rename Variable and Rename Method refactorings

Commenting Styles

Replace Magic Literals with Constants

The Extract Method refactoring

Replace Calculation with Temporary Variable

Extract Conditional to Method

The DRY principle

Single Responsibility Principle

Extract Class

Move Method to Class

The importance of tests

Exercise

Wrapping up

Summary

4. Using Mock Objects to Test Interactions

Hand writing a simple mock

Using the Python mocking framework

Mocking objects

Mocking return values

Mocking side effects

How much mocking is too much?

Mocks versus stubs versus fakes versus spies

Patching methods

An important gotcha when patching

Tying it all together

Summary

5. Working with Legacy Code

What is legacy code?

Understanding the code

What are characterization tests?

Using the Python interactive shell to understand the code

Writing a characterization test

Using pdb to understand the code

Some common pdb commands

Walking through a pdb session

Techniques to break dependencies

The Rope refactoring library

Separate initialization from execution

Use default values for parameters

Extract the method and test

Inject dependencies

Inherit and test

Stubbing local methods

Extract the method and stub

The cycle continues

Time to refactor

Long-term refactoring

Summary

6. Maintaining Your Test Suite

Goals of test maintenance

Organizing tests

Filesystem layout

Naming conventions

Test suite grouping

Making tests readable

Using docstrings

Using fixtures

Fixtures and patching

Using a custom test case class hierarchy

Writing tests closer to the domain

Writing helper methods

Writing better asserts

Using custom equality checkers

Using matchers

Summary

7. Executable Documentation with doctest

Our first doctest

Running the doctest

Test failures

Testing for exceptions

Package-level doctests

Maintaining doctests

Running a suite of doctests

Setup and teardown

Limitations of doctest

Doctest directives

How do doctests fit into the TDD process?

Summary

8. Extending unittest with nose2

Getting started with nose2

Writing tests for nose2

Setup and teardown

Parameterized tests

Generated tests

Layers

nose2 plugins

Doctest support

Writing test results to an XML file

Measuring test coverage

Debugging test failures

nose2 configuration

Summary

9. Unit Testing Patterns

Pattern – fast tests

Pattern – running a subset of tests

Test loaders

Using the load_tests protocol

Skipping tests

Pattern – using attributes

Attributes with vanilla unittests

Pattern – expected failures

Pattern – data-driven tests

Pattern – integration and system tests

Pattern – spies

Pattern – asserting a sequence of calls

Pattern – patching the open function

Pattern – mocking with mutable args

Summary

10. Tools to Improve Test-Driven Development

TDD tools

py.test

py.test versus nose2

Trial

Sure

PyHamcrest

Integrating with build tools

Paver

Integrating with packaging tools

Setuptools

Distutils

Integrating with continuous integration tools

Jenkins

Travis CI

Other tools

tox

Sphinx

IDE integration

Summary

A. Answers to Exercises

Red-Green-Refactor – The TDD Cycle

Code Smells and Refactoring

B. Working with Older Python Versions

Writing code that is compatible across versions

Running tests from the command line

Running the examples in this book

Index