mirror of https://github.com/python/cpython
44 lines
1.8 KiB
Python
44 lines
1.8 KiB
Python
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import ast
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class ASTTestMixin:
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"""Test mixing to have basic assertions for AST nodes."""
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def assertASTEqual(self, ast1, ast2):
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# Ensure the comparisons start at an AST node
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self.assertIsInstance(ast1, ast.AST)
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self.assertIsInstance(ast2, ast.AST)
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# An AST comparison routine modeled after ast.dump(), but
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# instead of string building, it traverses the two trees
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# in lock-step.
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def traverse_compare(a, b, missing=object()):
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if type(a) is not type(b):
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self.fail(f"{type(a)!r} is not {type(b)!r}")
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if isinstance(a, ast.AST):
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for field in a._fields:
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value1 = getattr(a, field, missing)
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value2 = getattr(b, field, missing)
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# Singletons are equal by definition, so further
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# testing can be skipped.
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if value1 is not value2:
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traverse_compare(value1, value2)
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elif isinstance(a, list):
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try:
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for node1, node2 in zip(a, b, strict=True):
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traverse_compare(node1, node2)
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except ValueError:
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# Attempt a "pretty" error ala assertSequenceEqual()
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len1 = len(a)
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len2 = len(b)
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if len1 > len2:
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what = "First"
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diff = len1 - len2
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else:
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what = "Second"
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diff = len2 - len1
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msg = f"{what} list contains {diff} additional elements."
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raise self.failureException(msg) from None
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elif a != b:
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self.fail(f"{a!r} != {b!r}")
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traverse_compare(ast1, ast2)
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