Book Image

Test-Driven Python Development

By : Siddharta Govindaraj
Book Image

Test-Driven Python Development

By: Siddharta Govindaraj

Overview of this book

This book starts with a look at the test-driven development process, and how it is different from the traditional way of writing code. All the concepts are presented in the context of a real application that is developed in a step-by-step manner over the course of the book. While exploring the common types of smelly code, we will go back into our example project and clean up the smells that we find. Additionally, we will use mocking to implement the parts of our example project that depend on other systems. Towards the end of the book, we'll take a look at the most common patterns and anti-patterns associated with test-driven development, including integration of test results into the development process.
Table of Contents (20 chapters)
Test-Driven Python Development
Credits
About the Author
Acknowledgments
About the Reviewers
www.PacktPub.com
Preface
Index

Understanding the code


The following is the code that we are going to be looking at in this chapter:

from datetime import datetime

from .stock import Stock
from .rule import PriceRule

class AlertProcessor:
    def __init__(self):
        self.exchange = {"GOOG": Stock("GOOG"), "AAPL": Stock("AAPL")}
        rule_1 = PriceRule("GOOG", lambda stock: stock.price > 10)
        rule_2 = PriceRule("AAPL", lambda stock: stock.price > 5)
        self.exchange["GOOG"].updated.connect(
            lambda stock: print(stock.symbol, stock.price) \
                if rule_1.matches(self.exchange) else None)
        self.exchange["AAPL"].updated.connect(
            lambda stock: print(stock.symbol, stock.price) \
                if rule_2.matches(self.exchange) else None)

        updates = []
        with open("updates.csv", "r") as fp:
            for line in fp.readlines():
                symbol, timestamp, price = line.split(",")
                updates.append((symbol, datetime.strptime(timestamp...