# documentación de Django - 1.10.7

# Código fuente para unittest.loader

    """Loading unittests."""

    import os
    import re
    import sys
    import traceback
    import types
    import functools
    import warnings

    from fnmatch import fnmatch

    from . import case, suite, util

    __unittest = True

    # what about .pyc (etc)
    # we would need to avoid loading the same tests multiple times
    # from '.py', *and* '.pyc'
    VALID_MODULE_NAME = re.compile(r'[_a-z]\w*\.py$', re.IGNORECASE)

    class _FailedTest(case.TestCase):
        _testMethodName = None

        def __init__(self, method_name, exception):
            self._exception = exception
            super(_FailedTest, self).__init__(method_name)

        def __getattr__(self, name):
            if name != self._testMethodName:
                return super(_FailedTest, self).__getattr__(name)
            def testFailure():
                raise self._exception
            return testFailure

    def _make_failed_import_test(name, suiteClass):
        message = 'Failed to import test module: %s\n%s' % (
            name, traceback.format_exc())
        return _make_failed_test(name, ImportError(message), suiteClass, message)

    def _make_failed_load_tests(name, exception, suiteClass):
        message = 'Failed to call load_tests:\n%s' % (traceback.format_exc(),)
        return _make_failed_test(
            name, exception, suiteClass, message)

    def _make_failed_test(methodname, exception, suiteClass, message):
        test = _FailedTest(methodname, exception)
        return suiteClass((test,)), message

    def _make_skipped_test(methodname, exception, suiteClass):
        @case.skip(str(exception))
        def testSkipped(self):
            pass
        attrs = {methodname: testSkipped}
        TestClass = type("ModuleSkipped", (case.TestCase,), attrs)
        return suiteClass((TestClass(methodname),))

    def _jython_aware_splitext(path):
        if path.lower().endswith('$py.class'):
            return path[:-9]
        return os.path.splitext(path)[0]

    class TestLoader(object):
        """
        This class is responsible for loading tests according to various criteria
        and returning them wrapped in a TestSuite
        """
        testMethodPrefix = 'test'
        sortTestMethodsUsing = staticmethod(util.three_way_cmp)
        suiteClass = suite.TestSuite
        _top_level_dir = None

        def __init__(self):
            super(TestLoader, self).__init__()
            self.errors = []
            # Tracks packages which we have called into via load_tests, to
            # avoid infinite re-entrancy.
            self._loading_packages = set()

        def loadTestsFromTestCase(self, testCaseClass):
            """Return a suite of all tests cases contained in testCaseClass"""
            if issubclass(testCaseClass, suite.TestSuite):
                raise TypeError("Test cases should not be derived from "
                                "TestSuite. Maybe you meant to derive from "
                                "TestCase?")
            testCaseNames = self.getTestCaseNames(testCaseClass)
            if not testCaseNames and hasattr(testCaseClass, 'runTest'):
                testCaseNames = ['runTest']
            loaded_suite = self.suiteClass(map(testCaseClass, testCaseNames))
            return loaded_suite

        # XXX After Python 3.5, remove backward compatibility hacks for
        # use_load_tests deprecation via *args and **kws.  See issue 16662.
        def loadTestsFromModule(self, module, *args, pattern=None, **kws):
            """Return a suite of all tests cases contained in the given module"""
            # This method used to take an undocumented and unofficial
            # use_load_tests argument.  For backward compatibility, we still
            # accept the argument (which can also be the first position) but we
            # ignore it and issue a deprecation warning if it's present.
            if len(args) > 0 or 'use_load_tests' in kws:
                warnings.warn('use_load_tests is deprecated and ignored',
                              DeprecationWarning)
                kws.pop('use_load_tests', None)
            if len(args) > 1:
                # Complain about the number of arguments, but don't forget the
                # required `module` argument.
                complaint = len(args) + 1
                raise TypeError('loadTestsFromModule() takes 1 positional argument but {} were given'.format(complaint))
            if len(kws) != 0:
                # Since the keyword arguments are unsorted (see PEP 468), just
                # pick the alphabetically sorted first argument to complain about,
                # if multiple were given.  At least the error message will be
                # predictable.
                complaint = sorted(kws)[0]
                raise TypeError("loadTestsFromModule() got an unexpected keyword argument '{}'".format(complaint))
            tests = []
            for name in dir(module):
                obj = getattr(module, name)
                if isinstance(obj, type) and issubclass(obj, case.TestCase):
                    tests.append(self.loadTestsFromTestCase(obj))

            load_tests = getattr(module, 'load_tests', None)
            tests = self.suiteClass(tests)
            if load_tests is not None:
                try:
                    return load_tests(self, tests, pattern)
                except Exception as e:
                    error_case, error_message = _make_failed_load_tests(
                        module.__name__, e, self.suiteClass)
                    self.errors.append(error_message)
                    return error_case
            return tests

        def loadTestsFromName(self, name, module=None):
            """Return a suite of all tests cases given a string specifier.

            The name may resolve either to a module, a test case class, a
            test method within a test case class, or a callable object which
            returns a TestCase or TestSuite instance.

            The method optionally resolves the names relative to a given module.
            """
            parts = name.split('.')
            error_case, error_message = None, None
            if module is None:
                parts_copy = parts[:]
                while parts_copy:
                    try:
                        module_name = '.'.join(parts_copy)
                        module = __import__(module_name)
                        break
                    except ImportError:
                        next_attribute = parts_copy.pop()
                        # Last error so we can give it to the user if needed.
                        error_case, error_message = _make_failed_import_test(
                            next_attribute, self.suiteClass)
                        if not parts_copy:
                            # Even the top level import failed: report that error.
                            self.errors.append(error_message)
                            return error_case
                parts = parts[1:]
            obj = module
            for part in parts:
                try:
                    parent, obj = obj, getattr(obj, part)
                except AttributeError as e:
                    # We can't traverse some part of the name.
                    if (getattr(obj, '__path__', None) is not None
                        and error_case is not None):
                        # This is a package (no __path__ per importlib docs), and we
                        # encountered an error importing something. We cannot tell
                        # the difference between package.WrongNameTestClass and
                        # package.wrong_module_name so we just report the
                        # ImportError - it is more informative.
                        self.errors.append(error_message)
                        return error_case
                    else:
                        # Otherwise, we signal that an AttributeError has occurred.
                        error_case, error_message = _make_failed_test(
                            part, e, self.suiteClass,
                            'Failed to access attribute:\n%s' % (
                                traceback.format_exc(),))
                        self.errors.append(error_message)
                        return error_case

            if isinstance(obj, types.ModuleType):
                return self.loadTestsFromModule(obj)
            elif isinstance(obj, type) and issubclass(obj, case.TestCase):
                return self.loadTestsFromTestCase(obj)
            elif (isinstance(obj, types.FunctionType) and
                  isinstance(parent, type) and
                  issubclass(parent, case.TestCase)):
                name = parts[-1]
                inst = parent(name)
                # static methods follow a different path
                if not isinstance(getattr(inst, name), types.FunctionType):
                    return self.suiteClass([inst])
            elif isinstance(obj, suite.TestSuite):
                return obj
            if callable(obj):
                test = obj()
                if isinstance(test, suite.TestSuite):
                    return test
                elif isinstance(test, case.TestCase):
                    return self.suiteClass([test])
                else:
                    raise TypeError("calling %s returned %s, not a test" %
                                    (obj, test))
            else:
                raise TypeError("don't know how to make test from: %s" % obj)

        def loadTestsFromNames(self, names, module=None):
            """Return a suite of all tests cases found using the given sequence
            of string specifiers. See 'loadTestsFromName()'.
            """
            suites = [self.loadTestsFromName(name, module) for name in names]
            return self.suiteClass(suites)

        def getTestCaseNames(self, testCaseClass):
            """Return a sorted sequence of method names found within testCaseClass
            """
            def isTestMethod(attrname, testCaseClass=testCaseClass,
                             prefix=self.testMethodPrefix):
                return attrname.startswith(prefix) and \
                    callable(getattr(testCaseClass, attrname))
            testFnNames = list(filter(isTestMethod, dir(testCaseClass)))
            if self.sortTestMethodsUsing:
                testFnNames.sort(key=functools.cmp_to_key(self.sortTestMethodsUsing))
            return testFnNames

        def discover(self, start_dir, pattern='test*.py', top_level_dir=None):
            """Find and return all test modules from the specified start
            directory, recursing into subdirectories to find them and return all
            tests found within them. Only test files that match the pattern will
            be loaded. (Using shell style pattern matching.)

            All test modules must be importable from the top level of the project.
            If the start directory is not the top level directory then the top
            level directory must be specified separately.

            If a test package name (directory with '__init__.py') matches the
            pattern then the package will be checked for a 'load_tests' function. If
            this exists then it will be called with (loader, tests, pattern) unless
            the package has already had load_tests called from the same discovery
            invocation, in which case the package module object is not scanned for
            tests - this ensures that when a package uses discover to further
            discover child tests that infinite recursion does not happen.

            If load_tests exists then discovery does *not* recurse into the package,
            load_tests is responsible for loading all tests in the package.

            The pattern is deliberately not stored as a loader attribute so that
            packages can continue discovery themselves. top_level_dir is stored so
            load_tests does not need to pass this argument in to loader.discover().

            Paths are sorted before being imported to ensure reproducible execution
            order even on filesystems with non-alphabetical ordering like ext3/4.
            """
            set_implicit_top = False
            if top_level_dir is None and self._top_level_dir is not None:
                # make top_level_dir optional if called from load_tests in a package
                top_level_dir = self._top_level_dir
            elif top_level_dir is None:
                set_implicit_top = True
                top_level_dir = start_dir

            top_level_dir = os.path.abspath(top_level_dir)

            if not top_level_dir in sys.path:
                # all test modules must be importable from the top level directory
                # should we *unconditionally* put the start directory in first
                # in sys.path to minimise likelihood of conflicts between installed
                # modules and development versions?
                sys.path.insert(0, top_level_dir)
            self._top_level_dir = top_level_dir

            is_not_importable = False
            is_namespace = False
            tests = []
            if os.path.isdir(os.path.abspath(start_dir)):
                start_dir = os.path.abspath(start_dir)
                if start_dir != top_level_dir:
                    is_not_importable = not os.path.isfile(os.path.join(start_dir, '__init__.py'))
            else:
                # support for discovery from dotted module names
                try:
                    __import__(start_dir)
                except ImportError:
                    is_not_importable = True
                else:
                    the_module = sys.modules[start_dir]
                    top_part = start_dir.split('.')[0]
                    try:
                        start_dir = os.path.abspath(
                           os.path.dirname((the_module.__file__)))
                    except AttributeError:
                        # look for namespace packages
                        try:
                            spec = the_module.__spec__
                        except AttributeError:
                            spec = None

                        if spec and spec.loader is None:
                            if spec.submodule_search_locations is not None:
                                is_namespace = True

                                for path in the_module.__path__:
                                    if (not set_implicit_top and
                                        not path.startswith(top_level_dir)):
                                        continue
                                    self._top_level_dir = \
                                        (path.split(the_module.__name__
                                             .replace(".", os.path.sep))[0])
                                    tests.extend(self._find_tests(path,
                                                                  pattern,
                                                                  namespace=True))
                        elif the_module.__name__ in sys.builtin_module_names:
                            # builtin module
                            raise TypeError('Can not use builtin modules '
                                            'as dotted module names') from None
                        else:
                            raise TypeError(
                                'don\'t know how to discover from {!r}'
                                .format(the_module)) from None

                    if set_implicit_top:
                        if not is_namespace:
                            self._top_level_dir = \
                               self._get_directory_containing_module(top_part)
                            sys.path.remove(top_level_dir)
                        else:
                            sys.path.remove(top_level_dir)

            if is_not_importable:
                raise ImportError('Start directory is not importable: %r' % start_dir)

            if not is_namespace:
                tests = list(self._find_tests(start_dir, pattern))
            return self.suiteClass(tests)

        def _get_directory_containing_module(self, module_name):
            module = sys.modules[module_name]
            full_path = os.path.abspath(module.__file__)

            if os.path.basename(full_path).lower().startswith('__init__.py'):
                return os.path.dirname(os.path.dirname(full_path))
            else:
                # here we have been given a module rather than a package - so
                # all we can do is search the *same* directory the module is in
                # should an exception be raised instead
                return os.path.dirname(full_path)

        def _get_name_from_path(self, path):
            if path == self._top_level_dir:
                return '.'
            path = _jython_aware_splitext(os.path.normpath(path))

            _relpath = os.path.relpath(path, self._top_level_dir)
            assert not os.path.isabs(_relpath), "Path must be within the project"
            assert not _relpath.startswith('..'), "Path must be within the project"

            name = _relpath.replace(os.path.sep, '.')
            return name

        def _get_module_from_name(self, name):
            __import__(name)
            return sys.modules[name]

        def _match_path(self, path, full_path, pattern):
            # override this method to use alternative matching strategy
            return fnmatch(path, pattern)

        def _find_tests(self, start_dir, pattern, namespace=False):
            """Used by discovery. Yields test suites it loads."""
            # Handle the __init__ in this package
            name = self._get_name_from_path(start_dir)
            # name is '.' when start_dir == top_level_dir (and top_level_dir is by
            # definition not a package).
            if name != '.' and name not in self._loading_packages:
                # name is in self._loading_packages while we have called into
                # loadTestsFromModule with name.
                tests, should_recurse = self._find_test_path(
                    start_dir, pattern, namespace)
                if tests is not None:
                    yield tests
                if not should_recurse:
                    # Either an error occurred, or load_tests was used by the
                    # package.
                    return
            # Handle the contents.
            paths = sorted(os.listdir(start_dir))
            for path in paths:
                full_path = os.path.join(start_dir, path)
                tests, should_recurse = self._find_test_path(
                    full_path, pattern, namespace)
                if tests is not None:
                    yield tests
                if should_recurse:
                    # we found a package that didn't use load_tests.
                    name = self._get_name_from_path(full_path)
                    self._loading_packages.add(name)
                    try:
                        yield from self._find_tests(full_path, pattern, namespace)
                    finally:
                        self._loading_packages.discard(name)

        def _find_test_path(self, full_path, pattern, namespace=False):
            """Used by discovery.

            Loads tests from a single file, or a directories' __init__.py when
            passed the directory.

            Returns a tuple (None_or_tests_from_file, should_recurse).
            """
            basename = os.path.basename(full_path)
            if os.path.isfile(full_path):
                if not VALID_MODULE_NAME.match(basename):
                    # valid Python identifiers only
                    return None, False
                if not self._match_path(basename, full_path, pattern):
                    return None, False
                # if the test file matches, load it
                name = self._get_name_from_path(full_path)
                try:
                    module = self._get_module_from_name(name)
                except case.SkipTest as e:
                    return _make_skipped_test(name, e, self.suiteClass), False
                except:
                    error_case, error_message = \
                        _make_failed_import_test(name, self.suiteClass)
                    self.errors.append(error_message)
                    return error_case, False
                else:
                    mod_file = os.path.abspath(
                        getattr(module, '__file__', full_path))
                    realpath = _jython_aware_splitext(
                        os.path.realpath(mod_file))
                    fullpath_noext = _jython_aware_splitext(
                        os.path.realpath(full_path))
                    if realpath.lower() != fullpath_noext.lower():
                        module_dir = os.path.dirname(realpath)
                        mod_name = _jython_aware_splitext(
                            os.path.basename(full_path))
                        expected_dir = os.path.dirname(full_path)
                        msg = ("%r module incorrectly imported from %r. Expected "
                               "%r. Is this module globally installed?")
                        raise ImportError(
                            msg % (mod_name, module_dir, expected_dir))
                    return self.loadTestsFromModule(module, pattern=pattern), False
            elif os.path.isdir(full_path):
                if (not namespace and
                    not os.path.isfile(os.path.join(full_path, '__init__.py'))):
                    return None, False

                load_tests = None
                tests = None
                name = self._get_name_from_path(full_path)
                try:
                    package = self._get_module_from_name(name)
                except case.SkipTest as e:
                    return _make_skipped_test(name, e, self.suiteClass), False
                except:
                    error_case, error_message = \
                        _make_failed_import_test(name, self.suiteClass)
                    self.errors.append(error_message)
                    return error_case, False
                else:
                    load_tests = getattr(package, 'load_tests', None)
                    # Mark this package as being in load_tests (possibly ;))
                    self._loading_packages.add(name)
                    try:
                        tests = self.loadTestsFromModule(package, pattern=pattern)
                        if load_tests is not None:
                            # loadTestsFromModule(package) has loaded tests for us.
                            return tests, False
                        return tests, True
                    finally:
                        self._loading_packages.discard(name)
            else:
                return None, False

    defaultTestLoader = TestLoader()

    def _makeLoader(prefix, sortUsing, suiteClass=None):
        loader = TestLoader()
        loader.sortTestMethodsUsing = sortUsing
        loader.testMethodPrefix = prefix
        if suiteClass:
            loader.suiteClass = suiteClass
        return loader

    def getTestCaseNames(testCaseClass, prefix, sortUsing=util.three_way_cmp):
        return _makeLoader(prefix, sortUsing).getTestCaseNames(testCaseClass)

    def makeSuite(testCaseClass, prefix='test', sortUsing=util.three_way_cmp,
                  suiteClass=suite.TestSuite):
        return _makeLoader(prefix, sortUsing, suiteClass).loadTestsFromTestCase(
            testCaseClass)

    def findTestCases(module, prefix='test', sortUsing=util.three_way_cmp,
                      suiteClass=suite.TestSuite):
        return _makeLoader(prefix, sortUsing, suiteClass).loadTestsFromModule(\
            module)