那么我们看下是如何去实现的呢。
首先我们使用的unittest.main()加载运行的测试用例，我们点击main看是否能跳转进去。正常跳转到这个函数里面。
我们可以看到有一个加载测试用例的\
默认加载的是defaultTestLoader，那么我去看看这里面有没有我们想要的。
这里我们可以看到 是一个类，这里有个定义的 test，我们看看。接下来是怎么用的。
那么问我们看下如何实现呢。 首选我们去defaultTestLoader
"""Loading unittests.""" import os import re import sys import traceback import types import functools import warnings from config import testname from fnmatch import fnmatch, fnmatchcase from unittest 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 = testname sortTestMethodsUsing = staticmethod(util.three_way_cmp) testNamePatterns = None 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 test 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 test 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 test 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 test 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 shouldIncludeMethod(attrname): if not attrname.startswith(self.testMethodPrefix): return False testFunc = getattr(testCaseClass, attrname) if not callable(testFunc): return False fullName = f'%s.%s.%s' % ( testCaseClass.__module__, testCaseClass.__qualname__, attrname ) return self.testNamePatterns is None or \ any(fnmatchcase(fullName, pattern) for pattern in self.testNamePatterns) testFnNames = list(filter(shouldIncludeMethod, 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, testNamePatterns=None): loader = TestLoader() loader.sortTestMethodsUsing = sortUsing loader.testMethodPrefix = prefix loader.testNamePatterns = testNamePatterns if suiteClass: loader.suiteClass = suiteClass return loader def getTestCaseNames(testCaseClass, prefix, sortUsing=util.three_way_cmp, testNamePatterns=None): return _makeLoader(prefix, sortUsing, testNamePatterns=testNamePatterns).getTestCaseNames(testCaseClass) def makeSuite(testCaseClass, prefix=testname, sortUsing=util.three_way_cmp, suiteClass=suite.TestSuite): return _makeLoader(prefix, sortUsing, suiteClass).loadTestsFromTestCase( testCaseClass) def findTestCases(module, prefix=testname, sortUsing=util.three_way_cmp, suiteClass=suite.TestSuite): return _makeLoader(prefix, sortUsing, suiteClass).loadTestsFromModule(\ module)
