（ Continuation of the previous section ） Underlying logic code

TestCase The test case ： The smallest unit , Business logic

TestSuite test suite ： A collection of test cases , Or a collection of test suites

    def createTests(self, from_discovery=False, Loader=None):
        if self.testNamePatterns:
            self.testLoader.testNamePatterns = self.testNamePatterns
        if from_discovery:
            loader = self.testLoader if Loader is None else Loader()
            self.test = loader.discover(self.start, self.pattern, self.top)
        elif self.testNames is None:
            self.test = self.testLoader.loadTestsFromModule(self.module)
        else:
            self.test = self.testLoader.loadTestsFromNames(self.testNames,
                                                           self.module)

TestFixtrue Test fixture ： Perform the actions before and after the test case

TestLoader Test loader ： Load test cases

def __init__(self, module='__main__', defaultTest=None, argv=None,
                    testRunner=None, testLoader=loader.defaultTestLoader,
                    exit=True, verbosity=1, failfast=None, catchbreak=None,
                    buffer=None, warnings=None, *, tb_locals=False):

TestRunner Test runner ： Run the specified test case

    def runTests(self):
        if self.catchbreak:
            installHandler()
        if self.testRunner is None:
            self.testRunner = runner.TextTestRunner
        if isinstance(self.testRunner, type):
            try:
                try:
                    testRunner = self.testRunner(verbosity=self.verbosity,
                                                 failfast=self.failfast,
                                                 buffer=self.buffer,
                                                 warnings=self.warnings,
                                                 tb_locals=self.tb_locals)
                except TypeError:
                    # didn't accept the tb_locals argument
                    testRunner = self.testRunner(verbosity=self.verbosity,
                                                 failfast=self.failfast,
                                                 buffer=self.buffer,
                                                 warnings=self.warnings)
            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
        self.result = testRunner.run(self.test)
        if self.exit:
            sys.exit(not self.result.wasSuccessful())

A brief analysis of the principle ：

if __name__ == '__main__':
    suite = unittest.defaultTestLoader.discover('./test', pattern='*.py')
    unittest.TextTestRunner().run(suite)