def loadPackage(self, package, recurse=False):
        """
        Load tests from a module object representing a package, and return a
        TestSuite containing those tests.

        Tests are only loaded from modules whose name begins with 'test_'
        (or whatever C{modulePrefix} is set to).

        @param package: a types.ModuleType object (or reasonable facsimile
        obtained by importing) which may contain tests.

        @param recurse: A boolean.  If True, inspect modules within packages
        within the given package (and so on), otherwise, only inspect modules
        in the package itself.

        @raise: TypeError if 'package' is not a package.

        @return: a TestSuite created with my suiteFactory, containing all the
        tests.
        """
        if not isPackage(package):
            raise TypeError("%r is not a package" % (package,))
        pkgobj = modules.getModule(package.__name__)
        if recurse:
            discovery = pkgobj.walkModules()
        else:
            discovery = pkgobj.iterModules()
        discovered = []
        for disco in discovery:
            if disco.name.split(".")[-1].startswith(self.modulePrefix):
                discovered.append(disco)
        suite = self.suiteFactory()
        for modinfo in self.sort(discovered):
            try:
                module = modinfo.load()
            except:
                thingToAdd = ErrorHolder(modinfo.name, failure.Failure())
            else:
                thingToAdd = self.loadModule(module)
            suite.addTest(thingToAdd)
        return suite

        Load tests from a module object representing a package, and return a
        TestSuite containing those tests.

        Tests are only loaded from modules whose name begins with 'test_'
        (or whatever C{modulePrefix} is set to).

        @param package: a types.ModuleType object (or reasonable facsimile
        obtained by importing) which may contain tests.

        @param recurse: A boolean.  If True, inspect modules within packages
        within the given package (and so on), otherwise, only inspect modules
        in the package itself.

        @raise: TypeError if 'package' is not a package.

        @return: a TestSuite created with my suiteFactory, containing all the
        tests.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/runner.py