test.py

# some tests were stolen from https://github.com/snoack/python-goto/blob/master/test_goto.py

import dis
from goto import with_goto, patch, goto, label
import pytest

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(patch(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 = []
    code.append('result = True')
    code.append('goto .foo')
    for i in range(2**12):
        code.append('label .l{0}'.format(i))
    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)


def test_jump_out_of_nested_2_loops():
    @with_goto
    def func():
        x = 1
        for i in range(2):
            for j in range(2):
                # These are more than 256 bytes of bytecode
                x += x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x
                x += x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x
                x += x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x+x

                goto .end
        label .end
        return (i, j)

    assert func() == (0, 0)


def test_jump_out_of_nested_11_loops():
    @with_goto
    def func():
        x = 1
        for i1 in range(2):
            for i2 in range(2):
                for i3 in range(2):
                    for i4 in range(2):
                        for i5 in range(2):
                            for i6 in range(2):
                                for i7 in range(2):
                                    for i8 in range(2):
                                        for i9 in range(2):
                                            for i10 in range(2):
                                                for i11 in range(2):
                                                    # These are more than
                                                    # 256 bytes of bytecode
                                                    x += x+x+x+x+x+x+x+x+x+x+x
                                                    x += x+x+x+x+x+x+x+x+x+x+x
                                                    x += x+x+x+x+x+x+x+x+x+x+x
                                                    x += x+x+x+x+x+x+x+x+x+x+x
                                                    x += x+x+x+x+x+x+x+x+x+x+x

                                                    goto .end
        label .end
        return (i1, i2, i3, i4, i5, i6, i7, i8, i9, i10, i11)

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


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 Exception:
            rv = 'except'
        finally:
            rv = 'finally'
        label .end
        return rv

    assert func() is None


def test_jump_into_try_block():
    # this is supported since try block takes no parameter
    @with_goto
    def func():
        try:
            label .block
        except Exception:
            pass
        goto .block


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

    pytest.raises(SyntaxError, with_goto, func)


def test_jump_to_ambiguous_label():
    def func():
        label .ambiguous
        goto .ambiguous
        label .ambiguous

    pytest.raises(SyntaxError, with_goto, func)


def test_implicit_pushpop_block():
    @with_goto
    def func():
        res = False
        goto .enter
        try:
            try:
                try:
                    label .enter
                    res = True
                    goto .outer
                except: pass
            except: pass
            label .outer
            goto .exit
        except: pass
        label .exit
        return res

    assert func()


def test_implicit_pushpop_block_2():
    @with_goto
    def func():
        res = False
        goto .enter
        try:
            label .enter
            with open("test.py", 'r'):
                res = True
                raise FileExistsError
        except FileExistsError:
            goto .end
        label .end
        return res

    assert func()


def test_lineno_decrease():
    def func():
        try:
            with open("something"):
                pass
            print(
                func(),
                func()
            )
        except:
            pass
        print("hehe")
    original = func.__code__
    modified = patch(original)

    linetab1 = tuple(dis.findlinestarts(original))
    linetab2 = tuple(dis.findlinestarts(modified))

    assert linetab1 == linetab2


def test_goto_except_block():
    def func():
        goto .exc
        try:
            pass
        except Exception:
            label .exc

    pytest.raises(SyntaxError, with_goto, func)


def test_goto_except_block_2():
    def func():
        goto .exc
        try:
            pass
        except:
            label .exc

    pytest.raises(SyntaxError, with_goto, func)