unittest 源代码分析（二）--main.py代码分析

1 介绍

   main.py是unittest主文件。

2 main.py调用过程

   TestProgram.__init__()  ==>  TestProgram.parseArgs() ==> TestProgram.createTests() ==> TestProgram.runTests()

   __init__() 初始化调用parseArgs()和runTests()

   parseArgs()解析输入参数

   createTests()创建测试用例集合

   runTests()执行测试用例

3 代码和注释

"""Unittest main program"""

import sys
import os
import types
from . import loader, runner
from .signals import installHandler

__unittest = True

#-h 输出帮助信息
FAILFAST     = "  -f, --failfast   Stop on first failure\n"
CATCHBREAK   = "  -c, --catch      Catch control-C and display results\n"
BUFFEROUTPUT = "  -b, --buffer     Buffer stdout and stderr during test runs\n"

# -f  用例遇到失败后停止，不在执行后面的用例
# -c  ctrl-c 中断后执行完输出测试结果

USAGE_AS_MAIN = """\
Usage: %(progName)s [options] [tests]

Options:
-h, --help       Show this message
-v, --verbose    Verbose output
-q, --quiet      Minimal output
%(failfast)s%(catchbreak)s%(buffer)s
Examples:
%(progName)s test_module               - run tests from test_module
%(progName)s module.TestClass          - run tests from module.TestClass
%(progName)s module.Class.test_method  - run specified test method

[tests] can be a list of any number of test modules, classes and test
methods.

Alternative Usage: %(progName)s discover [options]

Options:
-v, --verbose    Verbose output
%(failfast)s%(catchbreak)s%(buffer)s  -s directory     Directory to start discovery ('.' default)
-p pattern       Pattern to match test files ('test*.py' default)
-t directory     Top level directory of project (default to
start directory)

For test discovery all test modules must be importable from the top
level directory of the project.
"""

USAGE_FROM_MODULE = """\
Usage: %(progName)s [options] [test] [...]

Options:
-h, --help       Show this message
-v, --verbose    Verbose output
-q, --quiet      Minimal output
%(failfast)s%(catchbreak)s%(buffer)s
Examples:
%(progName)s                               - run default set of tests
%(progName)s MyTestSuite                   - run suite 'MyTestSuite'
%(progName)s MyTestCase.testSomething      - run MyTestCase.testSomething
%(progName)s MyTestCase                    - run all 'test*' test methods
in MyTestCase
"""

#TestProgram是unittest主类调用其他类完成测试

class TestProgram(object):
USAGE = USAGE_FROM_MODULE  #帮助信息

# defaults for testing
failfast = catchbreak = buffer = progName = None

def __init__(self, module='__main__', defaultTest=None, argv=None,
testRunner=None, testLoader=loader.defaultTestLoader,
exit=True, verbosity=1, failfast=None, catchbreak=None,
buffer=None):
if isinstance(module, basestring):
#basestring是str和unicode的超类（父类），也是抽象类，因此不能被调用和实例化，但可以被用来判断一个对象是否为str或者unicode的实例
self.module = __import__(module)
#动态加载测试用例文件
for part in module.split('.')[1:]:
self.module = getattr(self.module, part)
else:
self.module = module
if argv is None:
argv = sys.argv
#获取运行case的参数

self.exit = exit
self.failfast = failfast
self.catchbreak = catchbreak
self.verbosity = verbosity
self.buffer = buffer
self.defaultTest = defaultTest
self.testRunner = testRunner
#参数初始化
self.testLoader = testLoader
#初始化创建测试用例集的类
self.progName = os.path.basename(argv[0])
#调用测试用例文件赋值到self.progName
self.parseArgs(argv)
#参数解析函数
self.runTests()
#测试用例运行函数

#输出帮助信息函数
def usageExit(self, msg=None):
if msg:
print msg
usage = {'progName': self.progName, 'catchbreak': '', 'failfast': '',
'buffer': ''}
if self.failfast != False:
usage['failfast'] = FAILFAST
if self.catchbreak != False:
usage['catchbreak'] = CATCHBREAK
if self.buffer != False:
usage['buffer'] = BUFFEROUTPUT
print self.USAGE % usage
sys.exit(2)

#解析输入参数并生成测试用例
def parseArgs(self, argv):
#调用discover参数加载目录里文件，并生成测试用例集
if len(argv) > 1 and argv[1].lower() == 'discover':
self._do_discovery(argv[2:])
return

import getopt
long_opts = ['help', 'verbose', 'quiet', 'failfast', 'catch', 'buffer']
try:
options, args = getopt.getopt(argv[1:], 'hHvqfcb', long_opts)
for opt, value in options:
if opt in ('-h','-H','--help'):
self.usageExit()
if opt in ('-q','--quiet'):
self.verbosity = 0
if opt in ('-v','--verbose'):
self.verbosity = 2
if opt in ('-f','--failfast'):
if self.failfast is None:
self.failfast = True
# Should this raise an exception if -f is not valid?
if opt in ('-c','--catch'):
if self.catchbreak is None:
self.catchbreak = True
# Should this raise an exception if -c is not valid?
if opt in ('-b','--buffer'):
if self.buffer is None:
self.buffer = True
# Should this raise an exception if -b is not valid?
if len(args) == 0 and self.defaultTest is None:
# 没有指定测试用例
self.testNames = None
elif len(args) > 0:
# 指定测试用例
self.testNames = args
if __name__ == '__main__':
# to support python -m unittest ...
self.module = None
else:
self.testNames = (self.defaultTest,)
self.createTests()
#创建测试用例集合
except getopt.error, msg:
self.usageExit(msg)

#创建测试用例集合函数
def createTests(self):
if self.testNames is None:
# 没有指定测试用例加载整个文件做测试集合
self.test = self.testLoader.loadTestsFromModule(self.module)
else:
# 指定使用的测试用例，加载当个测试用例
self.test = self.testLoader.loadTestsFromNames(self.testNames,
self.module)
#将指定目录的文件加载成测试用例集
def _do_discovery(self, argv, Loader=None):
if Loader is None:
Loader = lambda: self.testLoader

# handle command line args for test discovery
self.progName = '%s discover' % self.progName
import optparse
parser = optparse.OptionParser()
parser.prog = self.progName
parser.add_option('-v', '--verbose', dest='verbose', default=False,
help='Verbose output', action='store_true')
if self.failfast != False:
parser.add_option('-f', '--failfast', dest='failfast', default=False,
help='Stop on first fail or error',
action='store_true')
if self.catchbreak != False:
parser.add_option('-c', '--catch', dest='catchbreak', default=False,
help='Catch ctrl-C and display results so far',
action='store_true')
if self.buffer != False:
parser.add_option('-b', '--buffer', dest='buffer', default=False,
help='Buffer stdout and stderr during tests',
action='store_true')
parser.add_option('-s', '--start-directory', dest='start', default='.',
help="Directory to start discovery ('.' default)")
parser.add_option('-p', '--pattern', dest='pattern', default='test*.py',
help="Pattern to match tests ('test*.py' default)")
parser.add_option('-t', '--top-level-directory'
4000
, dest='top', default=None,
help='Top level directory of project (defaults to start directory)')

options, args = parser.parse_args(argv)
if len(args) > 3:
self.usageExit()

for name, value in zip(('start', 'pattern', 'top'), args):
setattr(options, name, value)

# only set options from the parsing here
# if they weren't set explicitly in the constructor
if self.failfast is None:
self.failfast = options.failfast
if self.catchbreak is None:
self.catchbreak = options.catchbreak
if self.buffer is None:
self.buffer = options.buffer

if options.verbose:
self.verbosity = 2

start_dir = options.start
pattern = options.pattern
top_level_dir = options.top

loader = Loader()
#根据开始目录，匹配格式，顶层目录生成测试用例
self.test = loader.discover(start_dir, pattern, top_level_dir)

#执行测试用例
def runTests(self):
if self.catchbreak:
#注册捕捉信号函数
installHandler()
if self.testRunner is None:
self.testRunner = runner.TextTestRunner
if isinstance(self.testRunner, (type, types.ClassType)):
try:
testRunner = self.testRunner(verbosity=self.verbosity,
failfast=self.failfast,
buffer=self.buffer)
except TypeError:
# didn't accept the verbosity, buffer or failfast arguments
testRunner = self.testRunner()
else:
# it is assumed to be a TestRunner instance
testRunner = self.testRunner
#根据输入的参数初始化runner类
#调用runner.run运行测试用例
self.result = testRunner.run(self.test)
if self.exit:
sys.exit(not self.result.wasSuccessful())

#主函数
main = TestProgram