|
| 1 | +import unittest |
| 2 | +import builtins |
| 3 | +import os |
| 4 | +from platform import system as platform_system |
| 5 | + |
| 6 | + |
| 7 | +class ExceptionClassTests(unittest.TestCase): |
| 8 | + |
| 9 | + """Tests for anything relating to exception objects themselves (e.g., |
| 10 | + inheritance hierarchy)""" |
| 11 | + |
| 12 | + def test_builtins_new_style(self): |
| 13 | + self.assertTrue(issubclass(Exception, object)) |
| 14 | + |
| 15 | + def verify_instance_interface(self, ins): |
| 16 | + for attr in ("args", "__str__", "__repr__"): |
| 17 | + self.assertTrue(hasattr(ins, attr), |
| 18 | + "%s missing %s attribute" % |
| 19 | + (ins.__class__.__name__, attr)) |
| 20 | + |
| 21 | + # TODO: RUSTPYTHON |
| 22 | + @unittest.expectedFailure |
| 23 | + def test_inheritance(self): |
| 24 | + # Make sure the inheritance hierarchy matches the documentation |
| 25 | + exc_set = set() |
| 26 | + for object_ in builtins.__dict__.values(): |
| 27 | + try: |
| 28 | + if issubclass(object_, BaseException): |
| 29 | + exc_set.add(object_.__name__) |
| 30 | + except TypeError: |
| 31 | + pass |
| 32 | + |
| 33 | + inheritance_tree = open(os.path.join(os.path.split(__file__)[0], |
| 34 | + 'exception_hierarchy.txt')) |
| 35 | + try: |
| 36 | + superclass_name = inheritance_tree.readline().rstrip() |
| 37 | + try: |
| 38 | + last_exc = getattr(builtins, superclass_name) |
| 39 | + except AttributeError: |
| 40 | + self.fail("base class %s not a built-in" % superclass_name) |
| 41 | + self.assertIn(superclass_name, exc_set, |
| 42 | + '%s not found' % superclass_name) |
| 43 | + exc_set.discard(superclass_name) |
| 44 | + superclasses = [] # Loop will insert base exception |
| 45 | + last_depth = 0 |
| 46 | + for exc_line in inheritance_tree: |
| 47 | + exc_line = exc_line.rstrip() |
| 48 | + depth = exc_line.rindex('-') |
| 49 | + exc_name = exc_line[depth+2:] # Slice past space |
| 50 | + if '(' in exc_name: |
| 51 | + paren_index = exc_name.index('(') |
| 52 | + platform_name = exc_name[paren_index+1:-1] |
| 53 | + exc_name = exc_name[:paren_index-1] # Slice off space |
| 54 | + if platform_system() != platform_name: |
| 55 | + exc_set.discard(exc_name) |
| 56 | + continue |
| 57 | + if '[' in exc_name: |
| 58 | + left_bracket = exc_name.index('[') |
| 59 | + exc_name = exc_name[:left_bracket-1] # cover space |
| 60 | + try: |
| 61 | + exc = getattr(builtins, exc_name) |
| 62 | + except AttributeError: |
| 63 | + self.fail("%s not a built-in exception" % exc_name) |
| 64 | + if last_depth < depth: |
| 65 | + superclasses.append((last_depth, last_exc)) |
| 66 | + elif last_depth > depth: |
| 67 | + while superclasses[-1][0] >= depth: |
| 68 | + superclasses.pop() |
| 69 | + self.assertTrue(issubclass(exc, superclasses[-1][1]), |
| 70 | + "%s is not a subclass of %s" % (exc.__name__, |
| 71 | + superclasses[-1][1].__name__)) |
| 72 | + try: # Some exceptions require arguments; just skip them |
| 73 | + self.verify_instance_interface(exc()) |
| 74 | + except TypeError: |
| 75 | + pass |
| 76 | + self.assertIn(exc_name, exc_set) |
| 77 | + exc_set.discard(exc_name) |
| 78 | + last_exc = exc |
| 79 | + last_depth = depth |
| 80 | + finally: |
| 81 | + inheritance_tree.close() |
| 82 | + self.assertEqual(len(exc_set), 0, "%s not accounted for" % exc_set) |
| 83 | + |
| 84 | + interface_tests = ("length", "args", "str", "repr") |
| 85 | + |
| 86 | + def interface_test_driver(self, results): |
| 87 | + for test_name, (given, expected) in zip(self.interface_tests, results): |
| 88 | + self.assertEqual(given, expected, "%s: %s != %s" % (test_name, |
| 89 | + given, expected)) |
| 90 | + |
| 91 | + # TODO: RUSTPYTHON |
| 92 | + @unittest.expectedFailure |
| 93 | + def test_interface_single_arg(self): |
| 94 | + # Make sure interface works properly when given a single argument |
| 95 | + arg = "spam" |
| 96 | + exc = Exception(arg) |
| 97 | + results = ([len(exc.args), 1], [exc.args[0], arg], |
| 98 | + [str(exc), str(arg)], |
| 99 | + [repr(exc), '%s(%r)' % (exc.__class__.__name__, arg)]) |
| 100 | + self.interface_test_driver(results) |
| 101 | + |
| 102 | + def test_interface_multi_arg(self): |
| 103 | + # Make sure interface correct when multiple arguments given |
| 104 | + arg_count = 3 |
| 105 | + args = tuple(range(arg_count)) |
| 106 | + exc = Exception(*args) |
| 107 | + results = ([len(exc.args), arg_count], [exc.args, args], |
| 108 | + [str(exc), str(args)], |
| 109 | + [repr(exc), exc.__class__.__name__ + repr(exc.args)]) |
| 110 | + self.interface_test_driver(results) |
| 111 | + |
| 112 | + def test_interface_no_arg(self): |
| 113 | + # Make sure that with no args that interface is correct |
| 114 | + exc = Exception() |
| 115 | + results = ([len(exc.args), 0], [exc.args, tuple()], |
| 116 | + [str(exc), ''], |
| 117 | + [repr(exc), exc.__class__.__name__ + '()']) |
| 118 | + self.interface_test_driver(results) |
| 119 | + |
| 120 | +class UsageTests(unittest.TestCase): |
| 121 | + |
| 122 | + """Test usage of exceptions""" |
| 123 | + |
| 124 | + def raise_fails(self, object_): |
| 125 | + """Make sure that raising 'object_' triggers a TypeError.""" |
| 126 | + try: |
| 127 | + raise object_ |
| 128 | + except TypeError: |
| 129 | + return # What is expected. |
| 130 | + self.fail("TypeError expected for raising %s" % type(object_)) |
| 131 | + |
| 132 | + def catch_fails(self, object_): |
| 133 | + """Catching 'object_' should raise a TypeError.""" |
| 134 | + try: |
| 135 | + try: |
| 136 | + raise Exception |
| 137 | + except object_: |
| 138 | + pass |
| 139 | + except TypeError: |
| 140 | + pass |
| 141 | + except Exception: |
| 142 | + self.fail("TypeError expected when catching %s" % type(object_)) |
| 143 | + |
| 144 | + try: |
| 145 | + try: |
| 146 | + raise Exception |
| 147 | + except (object_,): |
| 148 | + pass |
| 149 | + except TypeError: |
| 150 | + return |
| 151 | + except Exception: |
| 152 | + self.fail("TypeError expected when catching %s as specified in a " |
| 153 | + "tuple" % type(object_)) |
| 154 | + |
| 155 | + def test_raise_new_style_non_exception(self): |
| 156 | + # You cannot raise a new-style class that does not inherit from |
| 157 | + # BaseException; the ability was not possible until BaseException's |
| 158 | + # introduction so no need to support new-style objects that do not |
| 159 | + # inherit from it. |
| 160 | + class NewStyleClass(object): |
| 161 | + pass |
| 162 | + self.raise_fails(NewStyleClass) |
| 163 | + self.raise_fails(NewStyleClass()) |
| 164 | + |
| 165 | + def test_raise_string(self): |
| 166 | + # Raising a string raises TypeError. |
| 167 | + self.raise_fails("spam") |
| 168 | + |
| 169 | + # TODO: RUSTPYTHON |
| 170 | + @unittest.expectedFailure |
| 171 | + def test_catch_non_BaseException(self): |
| 172 | + # Trying to catch an object that does not inherit from BaseException |
| 173 | + # is not allowed. |
| 174 | + class NonBaseException(object): |
| 175 | + pass |
| 176 | + self.catch_fails(NonBaseException) |
| 177 | + self.catch_fails(NonBaseException()) |
| 178 | + |
| 179 | + def test_catch_BaseException_instance(self): |
| 180 | + # Catching an instance of a BaseException subclass won't work. |
| 181 | + self.catch_fails(BaseException()) |
| 182 | + |
| 183 | + def test_catch_string(self): |
| 184 | + # Catching a string is bad. |
| 185 | + self.catch_fails("spam") |
| 186 | + |
| 187 | + |
| 188 | +if __name__ == '__main__': |
| 189 | + unittest.main() |
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