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72 lines
3 KiB
Python
72 lines
3 KiB
Python
"""bytecode_helper - support tools for testing correct bytecode generation"""
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import unittest
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import dis
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import io
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_UNSPECIFIED = object()
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class BytecodeTestCase(unittest.TestCase):
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"""Custom assertion methods for inspecting bytecode."""
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def get_disassembly_as_string(self, co):
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s = io.StringIO()
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dis.dis(co, file=s)
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return s.getvalue()
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def assertInstructionMatches(self, instr, expected, *, line_offset=0):
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# Deliberately test opname first, since that gives a more
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# meaningful error message than testing opcode
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self.assertEqual(instr.opname, expected.opname)
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self.assertEqual(instr.opcode, expected.opcode)
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self.assertEqual(instr.arg, expected.arg)
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self.assertEqual(instr.argval, expected.argval)
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self.assertEqual(instr.argrepr, expected.argrepr)
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self.assertEqual(instr.offset, expected.offset)
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if expected.starts_line is None:
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self.assertIsNone(instr.starts_line)
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else:
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self.assertEqual(instr.starts_line,
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expected.starts_line + line_offset)
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self.assertEqual(instr.is_jump_target, expected.is_jump_target)
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def assertBytecodeExactlyMatches(self, x, expected, *, line_offset=0):
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"""Throws AssertionError if any discrepancy is found in bytecode
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*x* is the object to be introspected
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*expected* is a list of dis.Instruction objects
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Set *line_offset* as appropriate to adjust for the location of the
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object to be disassembled within the test file. If the expected list
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assumes the first line is line 1, then an appropriate offset would be
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``1 - f.__code__.co_firstlineno``.
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"""
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actual = dis.get_instructions(x, line_offset=line_offset)
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self.assertEqual(list(actual), expected)
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def assertInBytecode(self, x, opname, argval=_UNSPECIFIED):
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"""Returns instr if op is found, otherwise throws AssertionError"""
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for instr in dis.get_instructions(x):
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if instr.opname == opname:
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if argval is _UNSPECIFIED or instr.argval == argval:
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return instr
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disassembly = self.get_disassembly_as_string(x)
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if argval is _UNSPECIFIED:
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msg = '%s not found in bytecode:\n%s' % (opname, disassembly)
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else:
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msg = '(%s,%r) not found in bytecode:\n%s'
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msg = msg % (opname, argval, disassembly)
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self.fail(msg)
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def assertNotInBytecode(self, x, opname, argval=_UNSPECIFIED):
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"""Throws AssertionError if op is found"""
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for instr in dis.get_instructions(x):
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if instr.opname == opname:
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disassembly = self.get_disassembly_as_string(co)
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if opargval is _UNSPECIFIED:
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msg = '%s occurs in bytecode:\n%s' % (opname, disassembly)
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elif instr.argval == argval:
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msg = '(%s,%r) occurs in bytecode:\n%s'
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msg = msg % (opname, argval, disassembly)
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self.fail(msg)
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