Add test_baseexception from CPython 3.8

Lib/test/exception_hierarchy.txt

@@ -0,0 +1,65 @@
+BaseException
+ +-- SystemExit
+ +-- KeyboardInterrupt
+ +-- GeneratorExit
+ +-- Exception
+      +-- StopIteration
+      +-- StopAsyncIteration
+      +-- ArithmeticError
+      |    +-- FloatingPointError
+      |    +-- OverflowError
+      |    +-- ZeroDivisionError
+      +-- AssertionError
+      +-- AttributeError
+      +-- BufferError
+      +-- EOFError
+      +-- ImportError
+      |    +-- ModuleNotFoundError
+      +-- LookupError
+      |    +-- IndexError
+      |    +-- KeyError
+      +-- MemoryError
+      +-- NameError
+      |    +-- UnboundLocalError
+      +-- OSError
+      |    +-- BlockingIOError
+      |    +-- ChildProcessError
+      |    +-- ConnectionError
+      |    |    +-- BrokenPipeError
+      |    |    +-- ConnectionAbortedError
+      |    |    +-- ConnectionRefusedError
+      |    |    +-- ConnectionResetError
+      |    +-- FileExistsError
+      |    +-- FileNotFoundError
+      |    +-- InterruptedError
+      |    +-- IsADirectoryError
+      |    +-- NotADirectoryError
+      |    +-- PermissionError
+      |    +-- ProcessLookupError
+      |    +-- TimeoutError
+      +-- ReferenceError
+      +-- RuntimeError
+      |    +-- NotImplementedError
+      |    +-- RecursionError
+      +-- SyntaxError
+      |    +-- TargetScopeError
+      |    +-- IndentationError
+      |         +-- TabError
+      +-- SystemError
+      +-- TypeError
+      +-- ValueError
+      |    +-- UnicodeError
+      |         +-- UnicodeDecodeError
+      |         +-- UnicodeEncodeError
+      |         +-- UnicodeTranslateError
+      +-- Warning
+           +-- DeprecationWarning
+           +-- PendingDeprecationWarning
+           +-- RuntimeWarning
+           +-- SyntaxWarning
+           +-- UserWarning
+           +-- FutureWarning
+           +-- ImportWarning
+           +-- UnicodeWarning
+           +-- BytesWarning
+           +-- ResourceWarning

Lib/test/test_baseexception.py

@@ -0,0 +1,183 @@
+import unittest
+import builtins
+import os
+from platform import system as platform_system
+
+
+class ExceptionClassTests(unittest.TestCase):
+
+    """Tests for anything relating to exception objects themselves (e.g.,
+    inheritance hierarchy)"""
+
+    def test_builtins_new_style(self):
+        self.assertTrue(issubclass(Exception, object))
+
+    def verify_instance_interface(self, ins):
+        for attr in ("args", "__str__", "__repr__"):
+            self.assertTrue(hasattr(ins, attr),
+                    "%s missing %s attribute" %
+                        (ins.__class__.__name__, attr))
+
+    def test_inheritance(self):
+        # Make sure the inheritance hierarchy matches the documentation
+        exc_set = set()
+        for object_ in builtins.__dict__.values():
+            try:
+                if issubclass(object_, BaseException):
+                    exc_set.add(object_.__name__)
+            except TypeError:
+                pass
+
+        inheritance_tree = open(os.path.join(os.path.split(__file__)[0],
+                                                'exception_hierarchy.txt'))
+        try:
+            superclass_name = inheritance_tree.readline().rstrip()
+            try:
+                last_exc = getattr(builtins, superclass_name)
+            except AttributeError:
+                self.fail("base class %s not a built-in" % superclass_name)
+            self.assertIn(superclass_name, exc_set,
+                          '%s not found' % superclass_name)
+            exc_set.discard(superclass_name)
+            superclasses = []  # Loop will insert base exception
+            last_depth = 0
+            for exc_line in inheritance_tree:
+                exc_line = exc_line.rstrip()
+                depth = exc_line.rindex('-')
+                exc_name = exc_line[depth+2:]  # Slice past space
+                if '(' in exc_name:
+                    paren_index = exc_name.index('(')
+                    platform_name = exc_name[paren_index+1:-1]
+                    exc_name = exc_name[:paren_index-1]  # Slice off space
+                    if platform_system() != platform_name:
+                        exc_set.discard(exc_name)
+                        continue
+                if '[' in exc_name:
+                    left_bracket = exc_name.index('[')
+                    exc_name = exc_name[:left_bracket-1]  # cover space
+                try:
+                    exc = getattr(builtins, exc_name)
+                except AttributeError:
+                    self.fail("%s not a built-in exception" % exc_name)
+                if last_depth < depth:
+                    superclasses.append((last_depth, last_exc))
+                elif last_depth > depth:
+                    while superclasses[-1][0] >= depth:
+                        superclasses.pop()
+                self.assertTrue(issubclass(exc, superclasses[-1][1]),
+                "%s is not a subclass of %s" % (exc.__name__,
+                    superclasses[-1][1].__name__))
+                try:  # Some exceptions require arguments; just skip them
+                    self.verify_instance_interface(exc())
+                except TypeError:
+                    pass
+                self.assertIn(exc_name, exc_set)
+                exc_set.discard(exc_name)
+                last_exc = exc
+                last_depth = depth
+        finally:
+            inheritance_tree.close()
+        self.assertEqual(len(exc_set), 0, "%s not accounted for" % exc_set)
+
+    interface_tests = ("length", "args", "str", "repr")
+
+    def interface_test_driver(self, results):
+        for test_name, (given, expected) in zip(self.interface_tests, results):
+            self.assertEqual(given, expected, "%s: %s != %s" % (test_name,
+                given, expected))
+
+    def test_interface_single_arg(self):
+        # Make sure interface works properly when given a single argument
+        arg = "spam"
+        exc = Exception(arg)
+        results = ([len(exc.args), 1], [exc.args[0], arg],
+                   [str(exc), str(arg)],
+            [repr(exc), '%s(%r)' % (exc.__class__.__name__, arg)])
+        self.interface_test_driver(results)
+
+    def test_interface_multi_arg(self):
+        # Make sure interface correct when multiple arguments given
+        arg_count = 3
+        args = tuple(range(arg_count))
+        exc = Exception(*args)
+        results = ([len(exc.args), arg_count], [exc.args, args],
+                [str(exc), str(args)],
+                [repr(exc), exc.__class__.__name__ + repr(exc.args)])
+        self.interface_test_driver(results)
+
+    def test_interface_no_arg(self):
+        # Make sure that with no args that interface is correct
+        exc = Exception()
+        results = ([len(exc.args), 0], [exc.args, tuple()],
+                [str(exc), ''],
+                [repr(exc), exc.__class__.__name__ + '()'])
+        self.interface_test_driver(results)
+
+class UsageTests(unittest.TestCase):
+
+    """Test usage of exceptions"""
+
+    def raise_fails(self, object_):
+        """Make sure that raising 'object_' triggers a TypeError."""
+        try:
+            raise object_
+        except TypeError:
+            return  # What is expected.
+        self.fail("TypeError expected for raising %s" % type(object_))
+
+    def catch_fails(self, object_):
+        """Catching 'object_' should raise a TypeError."""
+        try:
+            try:
+                raise Exception
+            except object_:
+                pass
+        except TypeError:
+            pass
+        except Exception:
+            self.fail("TypeError expected when catching %s" % type(object_))
+
+        try:
+            try:
+                raise Exception
+            except (object_,):
+                pass
+        except TypeError:
+            return
+        except Exception:
+            self.fail("TypeError expected when catching %s as specified in a "
+                        "tuple" % type(object_))
+
+    def test_raise_new_style_non_exception(self):
+        # You cannot raise a new-style class that does not inherit from
+        # BaseException; the ability was not possible until BaseException's
+        # introduction so no need to support new-style objects that do not
+        # inherit from it.
+        class NewStyleClass(object):
+            pass
+        self.raise_fails(NewStyleClass)
+        self.raise_fails(NewStyleClass())
+
+    def test_raise_string(self):
+        # Raising a string raises TypeError.
+        self.raise_fails("spam")
+
+    def test_catch_non_BaseException(self):
+        # Trying to catch an object that does not inherit from BaseException
+        # is not allowed.
+        class NonBaseException(object):
+            pass
+        self.catch_fails(NonBaseException)
+        self.catch_fails(NonBaseException())
+
+    def test_catch_BaseException_instance(self):
+        # Catching an instance of a BaseException subclass won't work.
+        self.catch_fails(BaseException())
+
+    def test_catch_string(self):
+        # Catching a string is bad.
+        self.catch_fails("spam")
+
+
+if __name__ == '__main__':
+    unittest.main()