Dive Into Python-Chapter 16. Functional Programming

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Dive Into Python-Chapter 16. Functional Programming Chapter 16. Functional Programming16.1. Diving inIn Chapter 13, Unit Testing, you learned about the philosophy of unittesting. In Chapter 14, Test-First Programming, you stepped through theimplementation of basic unit tests in Python. In Chapter 15, Refactoring, yousaw how unit testing makes large-scale refactoring easier. This chapter willbuild on those sample programs, but here we will focus more on advancedPython-specific techniques, rather than on unit testing itself.The following is a complete Python program that acts as a cheap and simpleregression testing framework. It takes unit tests that youve written forindividual modules, collects them all into one big test suite, and runs themall at once. I actually use this script as part of the build process for this book;I have unit tests for several of the example programs (not just the roman.pymodule featured in Chapter 13, Unit Testing), and the first thing myautomated build script does is run this program to make sure all myexamples still work. If this regression test fails, the build immediately stops.I dont want to release non-working examples any more than you want todownload them and sit around scratching your head and yelling at yourmonitor and wondering why they dont work.Example 16.1. regression.pyIf you have not already done so, you can download this and other examplesused in this book.Regression testing frameworkThis module will search for scripts in the same directory namedXYZtest.py. Each such script should be a test suite that tests amodule through PyUnit. (As of Python 2.1, PyUnit is included inthe standard library as unittest.) This script will aggregate allfound test suites into one big test suite and run them all at once.import sys, os, re, unittestdef regressionTest(): path = os.path.abspath(os.path.dirname(sys.argv[0])) files = os.listdir(path) test = re.compile(test.py$, re.IGNORECASE) files = filter(test.search, files) filenameToModuleName = lambda f: os.path.splitext(f)[0] moduleNames = map(filenameToModuleName, files) modules = map(__import__, moduleNames) load = unittest.defaultTestLoader.loadTestsFromModule return unittest.TestSuite(map(load, modules))if __name__ == __main__: unittest.main(defaultTest=regressionTest)Running this script in the same directory as the rest of the example scriptsthat come with this book will find all the unit tests, named moduletest.py,run them as a single test, and pass or fail them all at once.Example 16.2. Sample output of regression.py[you@localhost py]$ python regression.py -vhelp should fail with no object ... ok 1help should return known result for apihelper ... okhelp should honor collapse argument ... okhelp should honor spacing argument ... okbuildConnectionString should fail with list input ... ok 2buildConnectionString should fail with string input ... okbuildConnectionString should fail with tuple input ... okbuildConnectionString handles empty dictionary ... okbuildConnectionString returns known result with known input ... okfromRoman should only accept uppercase input ... ok 3toRoman should always return uppercase ... okfromRoman should fail with blank string ... okfromRoman should fail with malformed antecedents ... okfromRoman should fail with repeated pairs of numerals ... okfromRoman should fail with too many repeated numerals ... okfromRoman should give known result with known input ... oktoRoman should give known result with known input ... okfromRoman(toRoman(n))==n for all n ... oktoRoman should fail with non-integer input ... oktoRoman should fail with negative input ... oktoRoman should fail with large input ... oktoRoman should fail with 0 input ... okkgp a ref test ... okkgp b ref test ... okkgp c ref test ... okkgp d ref test ... okkgp e ref test ... okkgp f ref test ... okkgp g ref test ... ok----------------------------------------------------------------------Ran 29 tests in 2.799sOK1 The first 5 tests are from apihelpertest.py, which tests the examplescript from Chapter 4, The Power Of Introspection.2 The next 5 tests are from odbchelpertest.py, which tests the examplescript from Chapter 2, Your First Python Program.3 The rest are from romantest.py, which you studied in depth in Chapter13, Unit Testing.16.2. Finding the pathWhen running Python scripts from the command line, it is sometimes usefulto know where the currently running script is located on disk.This is one of those obscure little tricks that is virtually impossible to figureout on your own, but simple to remember once you see it. The key to it issys.argv. As you saw in Chapter 9, XML Processing, this is a list that holdsthe list of command-line arguments. How ...