Lib/test/test_dis.py

# Minimal tests for dis module

from test.support import run_unittest
import unittest
import sys
import dis
import io


def _f(a):
    print(a)
    return 1

dis_f = """\
 %-4d         0 LOAD_GLOBAL              0 (print)
              3 LOAD_FAST                0 (a)
              6 CALL_FUNCTION            1
              9 POP_TOP

 %-4d        10 LOAD_CONST               1 (1)
             13 RETURN_VALUE
"""%(_f.__code__.co_firstlineno + 1,
     _f.__code__.co_firstlineno + 2)


def bug708901():
    for res in range(1,
                     10):
        pass

dis_bug708901 = """\
 %-4d         0 SETUP_LOOP              23 (to 26)
              3 LOAD_GLOBAL              0 (range)
              6 LOAD_CONST               1 (1)

 %-4d         9 LOAD_CONST               2 (10)
             12 CALL_FUNCTION            2
             15 GET_ITER
        >>   16 FOR_ITER                 6 (to 25)
             19 STORE_FAST               0 (res)

 %-4d        22 JUMP_ABSOLUTE           16
        >>   25 POP_BLOCK
        >>   26 LOAD_CONST               0 (None)
             29 RETURN_VALUE
"""%(bug708901.__code__.co_firstlineno + 1,
     bug708901.__code__.co_firstlineno + 2,
     bug708901.__code__.co_firstlineno + 3)


def bug1333982(x=[]):
    assert 0, ([s for s in x] +
              1)
    pass

dis_bug1333982 = """\
 %-4d         0 LOAD_CONST               1 (0)
              3 JUMP_IF_TRUE            41 (to 47)
              6 POP_TOP
              7 LOAD_GLOBAL              0 (AssertionError)
             10 BUILD_LIST               0
             13 DUP_TOP
             14 STORE_FAST               1 (_[1])
             17 LOAD_FAST                0 (x)
             20 GET_ITER
        >>   21 FOR_ITER                13 (to 37)
             24 STORE_FAST               2 (s)
             27 LOAD_FAST                1 (_[1])
             30 LOAD_FAST                2 (s)
             33 LIST_APPEND
             34 JUMP_ABSOLUTE           21
        >>   37 DELETE_FAST              1 (_[1])

 %-4d        40 LOAD_CONST               2 (1)
             43 BINARY_ADD
             44 RAISE_VARARGS            2
        >>   47 POP_TOP

 %-4d        48 LOAD_CONST               0 (None)
             51 RETURN_VALUE
"""%(bug1333982.__code__.co_firstlineno + 1,
     bug1333982.__code__.co_firstlineno + 2,
     bug1333982.__code__.co_firstlineno + 3)

_BIG_LINENO_FORMAT = """\
%3d           0 LOAD_GLOBAL              0 (spam)
              3 POP_TOP
              4 LOAD_CONST               0 (None)
              7 RETURN_VALUE
"""

dis_module_expected_results = """\
Disassembly of f:
  4           0 LOAD_CONST               0 (None)
              3 RETURN_VALUE

Disassembly of g:
  5           0 LOAD_CONST               0 (None)
              3 RETURN_VALUE

"""


class DisTests(unittest.TestCase):
    def do_disassembly_test(self, func, expected):
        s = io.StringIO()
        save_stdout = sys.stdout
        sys.stdout = s
        dis.dis(func)
        sys.stdout = save_stdout
        got = s.getvalue()
        # Trim trailing blanks (if any).
        lines = got.split('\n')
        lines = [line.rstrip() for line in lines]
        expected = expected.split("\n")
        import difflib
        if expected != lines:
            self.fail(
                "events did not match expectation:\n" +
                "\n".join(difflib.ndiff(expected,
                                        lines)))

    def test_opmap(self):
        self.assertEqual(dis.opmap["STOP_CODE"], 0)
        self.assertEqual(dis.opmap["LOAD_CONST"] in dis.hasconst, True)
        self.assertEqual(dis.opmap["STORE_NAME"] in dis.hasname, True)

    def test_opname(self):
        self.assertEqual(dis.opname[dis.opmap["LOAD_FAST"]], "LOAD_FAST")

    def test_boundaries(self):
        self.assertEqual(dis.opmap["EXTENDED_ARG"], dis.EXTENDED_ARG)
        self.assertEqual(dis.opmap["STORE_NAME"], dis.HAVE_ARGUMENT)

    def test_dis(self):
        self.do_disassembly_test(_f, dis_f)

    def test_bug_708901(self):
        self.do_disassembly_test(bug708901, dis_bug708901)

    def test_bug_1333982(self):
        # XXX: re-enable this test!
        # This one is checking bytecodes generated for an `assert` statement,
        # so fails if the tests are run with -O.  Skip this test then.
        pass # Test has been disabled due to change in the way
             # list comps are handled. The byte code now includes
             # a memory address and a file location, so they change from
             # run to run.
        # if __debug__:
        #    self.do_disassembly_test(bug1333982, dis_bug1333982)

    def test_big_linenos(self):
        def func(count):
            namespace = {}
            func = "def foo():\n " + "".join(["\n "] * count + ["spam\n"])
            exec(func, namespace)
            return namespace['foo']

        # Test all small ranges
        for i in range(1, 300):
            expected = _BIG_LINENO_FORMAT % (i + 2)
            self.do_disassembly_test(func(i), expected)

        # Test some larger ranges too
        for i in range(300, 5000, 10):
            expected = _BIG_LINENO_FORMAT % (i + 2)
            self.do_disassembly_test(func(i), expected)

    def test_big_linenos(self):
        from test import dis_module
        self.do_disassembly_test(dis_module, dis_module_expected_results)

def test_main():
    run_unittest(DisTests)

if __name__ == "__main__":
    test_main()