test_goto.py

import sys
import pytest
from goto import with_goto

CODE = '''\
i = 0
result = []

label .start
if i == 10:
    goto .end

result.append(i)
i += 1
goto .start

label .end
'''

EXPECTED = list(range(10))


def test_range_as_code():
    ns = {}
    exec(with_goto(compile(CODE, '', 'exec')), ns)
    assert ns['result'] == EXPECTED


def make_function(code):
    lines = ['def func():']
    for line in code:
        lines.append('    ' + line)
    lines.append('    return result')

    ns = {}
    exec('\n'.join(lines), ns)
    return ns['func']


def test_range_as_function():
    assert with_goto(make_function(CODE.splitlines()))() == EXPECTED


def test_EXTENDED_ARG():
    code = []
    for i in range(2**16):
        code.append('label .l{0}'.format(i))
    code.append('result = True')
    code.append('goto .foo')
    code.append('result = "dead code"')
    code.append('label .foo')
    assert with_goto(make_function(code))() is True


def test_jump_out_of_loop():
    @with_goto
    def func():
        for i in range(10):
            goto .end
        label .end
        return i

    assert func() == 0


def test_jump_into_loop():
    def func():
        for i in range(10):
            label .loop
        goto .loop

    pytest.raises(SyntaxError, with_goto, func)

if sys.version_info >= (3, 6):
    def test_jump_out_of_nested_2_loops():
        @with_goto
        def func():
            for i in range(2):
                for j in range(2):
                    goto .end
            label .end
            return (i, j)

        assert func() == (0, 0)

    def test_jump_out_of_nested_3_loops():
        def func():
            for i in range(2):
                for j in range(2):
                    for k in range(2):
                        goto .end
            label .end
            return (i, j, k)

        pytest.raises(SyntaxError, with_goto, func)
else:
    def test_jump_out_of_nested_4_loops():
        @with_goto
        def func():
            for i in range(2):
                for j in range(2):
                    for k in range(2):
                        for m in range(2):
                            goto .end
            label .end
            return (i, j, k, m)

        assert func() == (0, 0, 0, 0)

    def test_jump_out_of_nested_5_loops():
        def func():
            for i in range(2):
                for j in range(2):
                    for k in range(2):
                        for m in range(2):
                            for n in range(2):
                                goto .end
            label .end
            return (i, j, k, m, n)

        pytest.raises(SyntaxError, with_goto, func)


def test_jump_across_loops():
    def func():
        for i in range(10):
            goto .other_loop

        for i in range(10):
            label .other_loop

    pytest.raises(SyntaxError, with_goto, func)


def test_jump_out_of_try_block():
    @with_goto
    def func():
        try:
            rv = None
            goto .end
        except:
            rv = 'except'
        finally:
            rv = 'finally'
        label .end
        return rv

    assert func() == None


def test_jump_into_try_block():
    def func():
        try:
            label .block
        except:
            pass
        goto .block

    pytest.raises(SyntaxError, with_goto, func)


def test_jump_to_unknown_label():
    def func():
        goto .unknown

    pytest.raises(SyntaxError, with_goto, func)


def test_function_is_copy():
    def func():
        pass

    func.foo = 'bar'
    newfunc = with_goto(func)

    assert newfunc is not func
    assert newfunc.foo == 'bar'