1 | # Tests some corner cases with isinstance() and issubclass(). While these |
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2 | # tests use new style classes and properties, they actually do whitebox |
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3 | # testing of error conditions uncovered when using extension types. |
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4 | |
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5 | import unittest |
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6 | from test import test_support |
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7 | import sys |
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8 | |
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9 | |
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10 | |
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11 | class TestIsInstanceExceptions(unittest.TestCase): |
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12 | # Test to make sure that an AttributeError when accessing the instance's |
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13 | # class's bases is masked. This was actually a bug in Python 2.2 and |
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14 | # 2.2.1 where the exception wasn't caught but it also wasn't being cleared |
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15 | # (leading to an "undetected error" in the debug build). Set up is, |
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16 | # isinstance(inst, cls) where: |
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17 | # |
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18 | # - inst isn't an InstanceType |
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19 | # - cls isn't a ClassType, a TypeType, or a TupleType |
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20 | # - cls has a __bases__ attribute |
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21 | # - inst has a __class__ attribute |
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22 | # - inst.__class__ as no __bases__ attribute |
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23 | # |
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24 | # Sounds complicated, I know, but this mimics a situation where an |
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25 | # extension type raises an AttributeError when its __bases__ attribute is |
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26 | # gotten. In that case, isinstance() should return False. |
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27 | def test_class_has_no_bases(self): |
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28 | class I(object): |
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29 | def getclass(self): |
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30 | # This must return an object that has no __bases__ attribute |
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31 | return None |
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32 | __class__ = property(getclass) |
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33 | |
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34 | class C(object): |
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35 | def getbases(self): |
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36 | return () |
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37 | __bases__ = property(getbases) |
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38 | |
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39 | self.assertEqual(False, isinstance(I(), C())) |
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40 | |
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41 | # Like above except that inst.__class__.__bases__ raises an exception |
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42 | # other than AttributeError |
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43 | def test_bases_raises_other_than_attribute_error(self): |
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44 | class E(object): |
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45 | def getbases(self): |
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46 | raise RuntimeError |
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47 | __bases__ = property(getbases) |
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48 | |
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49 | class I(object): |
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50 | def getclass(self): |
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51 | return E() |
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52 | __class__ = property(getclass) |
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53 | |
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54 | class C(object): |
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55 | def getbases(self): |
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56 | return () |
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57 | __bases__ = property(getbases) |
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58 | |
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59 | self.assertRaises(RuntimeError, isinstance, I(), C()) |
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60 | |
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61 | # Here's a situation where getattr(cls, '__bases__') raises an exception. |
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62 | # If that exception is not AttributeError, it should not get masked |
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63 | def test_dont_mask_non_attribute_error(self): |
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64 | class I: pass |
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65 | |
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66 | class C(object): |
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67 | def getbases(self): |
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68 | raise RuntimeError |
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69 | __bases__ = property(getbases) |
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70 | |
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71 | self.assertRaises(RuntimeError, isinstance, I(), C()) |
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72 | |
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73 | # Like above, except that getattr(cls, '__bases__') raises an |
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74 | # AttributeError, which /should/ get masked as a TypeError |
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75 | def test_mask_attribute_error(self): |
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76 | class I: pass |
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77 | |
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78 | class C(object): |
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79 | def getbases(self): |
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80 | raise AttributeError |
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81 | __bases__ = property(getbases) |
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82 | |
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83 | self.assertRaises(TypeError, isinstance, I(), C()) |
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84 | |
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85 | |
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86 | |
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87 | # These tests are similar to above, but tickle certain code paths in |
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88 | # issubclass() instead of isinstance() -- really PyObject_IsSubclass() |
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89 | # vs. PyObject_IsInstance(). |
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90 | class TestIsSubclassExceptions(unittest.TestCase): |
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91 | def test_dont_mask_non_attribute_error(self): |
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92 | class C(object): |
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93 | def getbases(self): |
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94 | raise RuntimeError |
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95 | __bases__ = property(getbases) |
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96 | |
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97 | class S(C): pass |
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98 | |
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99 | self.assertRaises(RuntimeError, issubclass, C(), S()) |
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100 | |
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101 | def test_mask_attribute_error(self): |
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102 | class C(object): |
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103 | def getbases(self): |
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104 | raise AttributeError |
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105 | __bases__ = property(getbases) |
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106 | |
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107 | class S(C): pass |
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108 | |
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109 | self.assertRaises(TypeError, issubclass, C(), S()) |
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110 | |
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111 | # Like above, but test the second branch, where the __bases__ of the |
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112 | # second arg (the cls arg) is tested. This means the first arg must |
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113 | # return a valid __bases__, and it's okay for it to be a normal -- |
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114 | # unrelated by inheritance -- class. |
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115 | def test_dont_mask_non_attribute_error_in_cls_arg(self): |
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116 | class B: pass |
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117 | |
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118 | class C(object): |
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119 | def getbases(self): |
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120 | raise RuntimeError |
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121 | __bases__ = property(getbases) |
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122 | |
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123 | self.assertRaises(RuntimeError, issubclass, B, C()) |
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124 | |
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125 | def test_mask_attribute_error_in_cls_arg(self): |
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126 | class B: pass |
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127 | |
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128 | class C(object): |
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129 | def getbases(self): |
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130 | raise AttributeError |
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131 | __bases__ = property(getbases) |
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132 | |
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133 | self.assertRaises(TypeError, issubclass, B, C()) |
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134 | |
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135 | |
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136 | |
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137 | # meta classes for creating abstract classes and instances |
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138 | class AbstractClass(object): |
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139 | def __init__(self, bases): |
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140 | self.bases = bases |
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141 | |
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142 | def getbases(self): |
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143 | return self.bases |
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144 | __bases__ = property(getbases) |
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145 | |
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146 | def __call__(self): |
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147 | return AbstractInstance(self) |
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148 | |
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149 | class AbstractInstance(object): |
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150 | def __init__(self, klass): |
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151 | self.klass = klass |
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152 | |
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153 | def getclass(self): |
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154 | return self.klass |
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155 | __class__ = property(getclass) |
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156 | |
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157 | # abstract classes |
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158 | AbstractSuper = AbstractClass(bases=()) |
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159 | |
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160 | AbstractChild = AbstractClass(bases=(AbstractSuper,)) |
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161 | |
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162 | # normal classes |
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163 | class Super: |
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164 | pass |
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165 | |
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166 | class Child(Super): |
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167 | pass |
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168 | |
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169 | # new-style classes |
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170 | class NewSuper(object): |
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171 | pass |
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172 | |
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173 | class NewChild(NewSuper): |
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174 | pass |
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175 | |
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176 | |
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177 | |
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178 | class TestIsInstanceIsSubclass(unittest.TestCase): |
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179 | # Tests to ensure that isinstance and issubclass work on abstract |
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180 | # classes and instances. Before the 2.2 release, TypeErrors were |
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181 | # raised when boolean values should have been returned. The bug was |
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182 | # triggered by mixing 'normal' classes and instances were with |
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183 | # 'abstract' classes and instances. This case tries to test all |
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184 | # combinations. |
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185 | |
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186 | def test_isinstance_normal(self): |
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187 | # normal instances |
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188 | self.assertEqual(True, isinstance(Super(), Super)) |
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189 | self.assertEqual(False, isinstance(Super(), Child)) |
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190 | self.assertEqual(False, isinstance(Super(), AbstractSuper)) |
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191 | self.assertEqual(False, isinstance(Super(), AbstractChild)) |
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192 | |
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193 | self.assertEqual(True, isinstance(Child(), Super)) |
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194 | self.assertEqual(False, isinstance(Child(), AbstractSuper)) |
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195 | |
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196 | def test_isinstance_abstract(self): |
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197 | # abstract instances |
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198 | self.assertEqual(True, isinstance(AbstractSuper(), AbstractSuper)) |
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199 | self.assertEqual(False, isinstance(AbstractSuper(), AbstractChild)) |
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200 | self.assertEqual(False, isinstance(AbstractSuper(), Super)) |
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201 | self.assertEqual(False, isinstance(AbstractSuper(), Child)) |
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202 | |
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203 | self.assertEqual(True, isinstance(AbstractChild(), AbstractChild)) |
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204 | self.assertEqual(True, isinstance(AbstractChild(), AbstractSuper)) |
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205 | self.assertEqual(False, isinstance(AbstractChild(), Super)) |
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206 | self.assertEqual(False, isinstance(AbstractChild(), Child)) |
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207 | |
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208 | def test_subclass_normal(self): |
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209 | # normal classes |
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210 | self.assertEqual(True, issubclass(Super, Super)) |
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211 | self.assertEqual(False, issubclass(Super, AbstractSuper)) |
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212 | self.assertEqual(False, issubclass(Super, Child)) |
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213 | |
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214 | self.assertEqual(True, issubclass(Child, Child)) |
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215 | self.assertEqual(True, issubclass(Child, Super)) |
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216 | self.assertEqual(False, issubclass(Child, AbstractSuper)) |
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217 | |
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218 | def test_subclass_abstract(self): |
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219 | # abstract classes |
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220 | self.assertEqual(True, issubclass(AbstractSuper, AbstractSuper)) |
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221 | self.assertEqual(False, issubclass(AbstractSuper, AbstractChild)) |
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222 | self.assertEqual(False, issubclass(AbstractSuper, Child)) |
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223 | |
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224 | self.assertEqual(True, issubclass(AbstractChild, AbstractChild)) |
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225 | self.assertEqual(True, issubclass(AbstractChild, AbstractSuper)) |
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226 | self.assertEqual(False, issubclass(AbstractChild, Super)) |
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227 | self.assertEqual(False, issubclass(AbstractChild, Child)) |
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228 | |
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229 | def test_subclass_tuple(self): |
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230 | # test with a tuple as the second argument classes |
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231 | self.assertEqual(True, issubclass(Child, (Child,))) |
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232 | self.assertEqual(True, issubclass(Child, (Super,))) |
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233 | self.assertEqual(False, issubclass(Super, (Child,))) |
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234 | self.assertEqual(True, issubclass(Super, (Child, Super))) |
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235 | self.assertEqual(False, issubclass(Child, ())) |
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236 | self.assertEqual(True, issubclass(Super, (Child, (Super,)))) |
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237 | |
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238 | self.assertEqual(True, issubclass(NewChild, (NewChild,))) |
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239 | self.assertEqual(True, issubclass(NewChild, (NewSuper,))) |
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240 | self.assertEqual(False, issubclass(NewSuper, (NewChild,))) |
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241 | self.assertEqual(True, issubclass(NewSuper, (NewChild, NewSuper))) |
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242 | self.assertEqual(False, issubclass(NewChild, ())) |
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243 | self.assertEqual(True, issubclass(NewSuper, (NewChild, (NewSuper,)))) |
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244 | |
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245 | self.assertEqual(True, issubclass(int, (long, (float, int)))) |
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246 | if test_support.have_unicode: |
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247 | self.assertEqual(True, issubclass(str, (unicode, (Child, NewChild, basestring)))) |
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248 | |
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249 | def test_subclass_recursion_limit(self): |
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250 | # make sure that issubclass raises RuntimeError before the C stack is |
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251 | # blown |
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252 | self.assertRaises(RuntimeError, blowstack, issubclass, str, str) |
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253 | |
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254 | def test_isinstance_recursion_limit(self): |
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255 | # make sure that issubclass raises RuntimeError before the C stack is |
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256 | # blown |
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257 | self.assertRaises(RuntimeError, blowstack, isinstance, '', str) |
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258 | |
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259 | def blowstack(fxn, arg, compare_to): |
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260 | # Make sure that calling isinstance with a deeply nested tuple for its |
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261 | # argument will raise RuntimeError eventually. |
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262 | tuple_arg = (compare_to,) |
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263 | for cnt in xrange(sys.getrecursionlimit()+5): |
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264 | tuple_arg = (tuple_arg,) |
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265 | fxn(arg, tuple_arg) |
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266 | |
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267 | |
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268 | def test_main(): |
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269 | test_support.run_unittest( |
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270 | TestIsInstanceExceptions, |
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271 | TestIsSubclassExceptions, |
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272 | TestIsInstanceIsSubclass |
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273 | ) |
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274 | |
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275 | |
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276 | if __name__ == '__main__': |
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277 | test_main() |
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