tractor/tests/test_debugger.py

"""
That "native" debug mode better work!

All these tests can be understood (somewhat) by running the equivalent
`examples/debugging/` scripts manually.

TODO:
    - none of these tests have been run successfully on windows yet but
      there's been manual testing that verified it works.
    - wonder if any of it'll work on OS X?

"""
from os import path
from typing import Optional
import platform
import sys
import time

import pytest
import pexpect
from pexpect.exceptions import (
    TIMEOUT,
    EOF,
)

from conftest import repodir

# TODO: The next great debugger audit could be done by you!
# - recurrent entry to breakpoint() from single actor *after* and an
#   error in another task?
# - root error before child errors
# - root error after child errors
# - root error before child breakpoint
# - root error after child breakpoint
# - recurrent root errors


if platform.system() == 'Windows':
    pytest.skip(
        'Debugger tests have no windows support (yet)',
        allow_module_level=True,
    )


def examples_dir():
    """Return the abspath to the examples directory.
    """
    return path.join(repodir(), 'examples', 'debugging/')


def mk_cmd(ex_name: str) -> str:
    """Generate a command suitable to pass to ``pexpect.spawn()``.
    """
    return ' '.join(
        ['python',
         path.join(examples_dir(), f'{ex_name}.py')]
    )


@pytest.fixture
def spawn(
    start_method,
    testdir,
    arb_addr,
) -> 'pexpect.spawn':

    if start_method != 'trio':
        pytest.skip(
            "Debugger tests are only supported on the trio backend"
        )

    def _spawn(cmd):
        return testdir.spawn(
            cmd=mk_cmd(cmd),
            expect_timeout=3,
        )

    return _spawn


def assert_before(
    child,
    patts: list[str],

) -> None:

    before = str(child.before.decode())

    for patt in patts:
        try:
            assert patt in before
        except AssertionError:
            print(before)
            raise


@pytest.fixture(
    params=[False, True],
    ids='ctl-c={}'.format,
)
def ctlc(request) -> bool:

    use_ctlc = request.param

    if (
        sys.version_info <= (3, 10)
        and use_ctlc
    ):
        # on 3.9 it seems the REPL UX
        # is highly unreliable and frankly annoying
        # to test for. It does work from manual testing
        # but i just don't think it's wroth it to try
        # and get this working especially since we want to
        # be 3.10+ mega-asap.
        pytest.skip('Py3.9 and `pdbpp` son no bueno..')

    if use_ctlc:
        # XXX: disable pygments highlighting for auto-tests
        # since some envs (like actions CI) will struggle
        # the the added color-char encoding..
        from tractor._debug import TractorConfig
        TractorConfig.use_pygements = False

    yield use_ctlc


@pytest.mark.parametrize(
    'user_in_out',
    [
        ('c', 'AssertionError'),
        ('q', 'AssertionError'),
    ],
    ids=lambda item: f'{item[0]} -> {item[1]}',
)
def test_root_actor_error(spawn, user_in_out):
    """Demonstrate crash handler entering pdbpp from basic error in root actor.
    """
    user_input, expect_err_str = user_in_out

    child = spawn('root_actor_error')

    # scan for the pdbpp prompt
    child.expect(r"\(Pdb\+\+\)")

    before = str(child.before.decode())

    # make sure expected logging and error arrives
    assert "Attaching to pdb in crashed actor: ('root'" in before
    assert 'AssertionError' in before

    # send user command
    child.sendline(user_input)

    # process should exit
    child.expect(pexpect.EOF)
    assert expect_err_str in str(child.before)


@pytest.mark.parametrize(
    'user_in_out',
    [
        ('c', None),
        ('q', 'bdb.BdbQuit'),
    ],
    ids=lambda item: f'{item[0]} -> {item[1]}',
)
def test_root_actor_bp(spawn, user_in_out):
    """Demonstrate breakpoint from in root actor.
    """
    user_input, expect_err_str = user_in_out
    child = spawn('root_actor_breakpoint')

    # scan for the pdbpp prompt
    child.expect(r"\(Pdb\+\+\)")

    assert 'Error' not in str(child.before)

    # send user command
    child.sendline(user_input)
    child.expect('\r\n')

    # process should exit
    child.expect(pexpect.EOF)

    if expect_err_str is None:
        assert 'Error' not in str(child.before)
    else:
        assert expect_err_str in str(child.before)


def do_ctlc(
    child,
    count: int = 3,
    delay: float = 0.1,
    patt: Optional[str] = None,

    # XXX: literally no idea why this is an issue in CI but likely will
    # flush out (hopefully) with proper 3.10 release of `pdbpp`...
    expect_prompt: bool = True,

) -> None:

    # make sure ctl-c sends don't do anything but repeat output
    for _ in range(count):
        time.sleep(delay)
        child.sendcontrol('c')

        # TODO: figure out why this makes CI fail..
        # if you run this test manually it works just fine..
        from conftest import _ci_env
        if expect_prompt and not _ci_env:
            before = str(child.before.decode())
            time.sleep(delay)
            child.expect(r"\(Pdb\+\+\)")
            time.sleep(delay)

            if patt:
                # should see the last line on console
                assert patt in before


def test_root_actor_bp_forever(
    spawn,
    ctlc: bool,
):
    "Re-enter a breakpoint from the root actor-task."
    child = spawn('root_actor_breakpoint_forever')

    # do some "next" commands to demonstrate recurrent breakpoint
    # entries
    for _ in range(10):

        child.expect(r"\(Pdb\+\+\)")

        if ctlc:
            do_ctlc(child)

        child.sendline('next')

    # do one continue which should trigger a
    # new task to lock the tty
    child.sendline('continue')
    child.expect(r"\(Pdb\+\+\)")

    # seems that if we hit ctrl-c too fast the
    # sigint guard machinery might not kick in..
    time.sleep(0.001)

    if ctlc:
        do_ctlc(child)

    # XXX: this previously caused a bug!
    child.sendline('n')
    child.expect(r"\(Pdb\+\+\)")

    child.sendline('n')
    child.expect(r"\(Pdb\+\+\)")

    # quit out of the loop
    child.sendline('q')
    child.expect(pexpect.EOF)


@pytest.mark.parametrize(
    'do_next',
    (True, False),
    ids='do_next={}'.format,
)
def test_subactor_error(
    spawn,
    ctlc: bool,
    do_next: bool,
):
    "Single subactor raising an error"

    child = spawn('subactor_error')

    # scan for the pdbpp prompt
    child.expect(r"\(Pdb\+\+\)")

    before = str(child.before.decode())
    assert "Attaching to pdb in crashed actor: ('name_error'" in before

    if do_next:
        child.sendline('n')

    else:
        # make sure ctl-c sends don't do anything but repeat output
        if ctlc:
            do_ctlc(
                child,
            )

        # send user command and (in this case it's the same for 'continue'
        # vs. 'quit') the debugger should enter a second time in the nursery
        # creating actor
        child.sendline('continue')

    child.expect(r"\(Pdb\+\+\)")
    before = str(child.before.decode())

    # root actor gets debugger engaged
    assert "Attaching to pdb in crashed actor: ('root'" in before
    # error is a remote error propagated from the subactor
    assert "RemoteActorError: ('name_error'" in before

    # another round
    if ctlc:
        do_ctlc(child)

    child.sendline('c')
    child.expect('\r\n')

    # process should exit
    child.expect(pexpect.EOF)


def test_subactor_breakpoint(
    spawn,
    ctlc: bool,
):
    "Single subactor with an infinite breakpoint loop"

    child = spawn('subactor_breakpoint')

    # scan for the pdbpp prompt
    child.expect(r"\(Pdb\+\+\)")

    before = str(child.before.decode())
    assert "Attaching pdb to actor: ('breakpoint_forever'" in before

    # do some "next" commands to demonstrate recurrent breakpoint
    # entries
    for _ in range(10):
        child.sendline('next')
        child.expect(r"\(Pdb\+\+\)")

        if ctlc:
            do_ctlc(child)

    # now run some "continues" to show re-entries
    for _ in range(5):
        child.sendline('continue')
        child.expect(r"\(Pdb\+\+\)")
        before = str(child.before.decode())
        assert "Attaching pdb to actor: ('breakpoint_forever'" in before

        if ctlc:
            do_ctlc(child)

    # finally quit the loop
    child.sendline('q')

    # child process should exit but parent will capture pdb.BdbQuit
    child.expect(r"\(Pdb\+\+\)")

    before = str(child.before.decode())
    assert "RemoteActorError: ('breakpoint_forever'" in before
    assert 'bdb.BdbQuit' in before

    if ctlc:
        do_ctlc(child)

    # quit the parent
    child.sendline('c')

    # process should exit
    child.expect(pexpect.EOF)

    before = str(child.before.decode())
    assert "RemoteActorError: ('breakpoint_forever'" in before
    assert 'bdb.BdbQuit' in before


def test_multi_subactors(
    spawn,
    ctlc: bool,
):
    '''
    Multiple subactors, both erroring and
    breakpointing as well as a nested subactor erroring.

    '''
    child = spawn(r'multi_subactors')

    # scan for the pdbpp prompt
    child.expect(r"\(Pdb\+\+\)")

    before = str(child.before.decode())
    assert "Attaching pdb to actor: ('breakpoint_forever'" in before

    if ctlc:
        do_ctlc(child)

    # do some "next" commands to demonstrate recurrent breakpoint
    # entries
    for _ in range(10):
        child.sendline('next')
        child.expect(r"\(Pdb\+\+\)")

        if ctlc:
            do_ctlc(child)

    # continue to next error
    child.sendline('c')

    # first name_error failure
    child.expect(r"\(Pdb\+\+\)")
    before = str(child.before.decode())
    assert "Attaching to pdb in crashed actor: ('name_error'" in before
    assert "NameError" in before

    if ctlc:
        do_ctlc(child)

    # continue again
    child.sendline('c')

    # 2nd name_error failure
    child.expect(r"\(Pdb\+\+\)")

    assert_before(child, [
        "Attaching to pdb in crashed actor: ('name_error_1'",
        "NameError",
    ])

    if ctlc:
        do_ctlc(child)

    # breakpoint loop should re-engage
    child.sendline('c')
    child.expect(r"\(Pdb\+\+\)")
    before = str(child.before.decode())
    assert "Attaching pdb to actor: ('breakpoint_forever'" in before

    if ctlc:
        do_ctlc(child)

    # wait for spawn error to show up
    spawn_err = "Attaching to pdb in crashed actor: ('spawn_error'"
    start = time.time()
    while (
        spawn_err not in before
        and (time.time() - start) < 3
    ):
        child.sendline('c')
        time.sleep(0.1)
        child.expect(r"\(Pdb\+\+\)")
        before = str(child.before.decode())

        if ctlc:
            do_ctlc(child)

    # 2nd depth nursery should trigger
    if not ctlc:
        assert_before(child, [
            spawn_err,
            "RemoteActorError: ('name_error_1'",
        ])

    # now run some "continues" to show re-entries
    for _ in range(5):
        child.sendline('c')
        child.expect(r"\(Pdb\+\+\)")

    # quit the loop and expect parent to attach
    child.sendline('q')
    child.expect(r"\(Pdb\+\+\)")
    before = str(child.before.decode())

    assert_before(child, [
        # debugger attaches to root
        "Attaching to pdb in crashed actor: ('root'",

        # expect a multierror with exceptions for each sub-actor
        "RemoteActorError: ('breakpoint_forever'",
        "RemoteActorError: ('name_error'",
        "RemoteActorError: ('spawn_error'",
        "RemoteActorError: ('name_error_1'",
        'bdb.BdbQuit',
    ])

    if ctlc:
        do_ctlc(child)

    # process should exit
    child.sendline('c')
    child.expect(pexpect.EOF)

    # repeat of previous multierror for final output
    assert_before(child, [
        "RemoteActorError: ('breakpoint_forever'",
        "RemoteActorError: ('name_error'",
        "RemoteActorError: ('spawn_error'",
        "RemoteActorError: ('name_error_1'",
        'bdb.BdbQuit',
    ])


def test_multi_daemon_subactors(
    spawn,
    loglevel: str,
    ctlc: bool
):
    '''
    Multiple daemon subactors, both erroring and breakpointing within a
    stream.

    '''
    child = spawn('multi_daemon_subactors')

    child.expect(r"\(Pdb\+\+\)")

    # there is a race for which subactor will acquire
    # the root's tty lock first

    before = str(child.before.decode())

    bp_forever_msg = "Attaching pdb to actor: ('bp_forever'"
    name_error_msg = "NameError"

    if bp_forever_msg in before:
        next_msg = name_error_msg

    elif name_error_msg in before:
        next_msg = bp_forever_msg

    else:
        raise ValueError("Neither log msg was found !?")

    if ctlc:
        do_ctlc(child)

    # NOTE: previously since we did not have clobber prevention
    # in the root actor this final resume could result in the debugger
    # tearing down since both child actors would be cancelled and it was
    # unlikely that `bp_forever` would re-acquire the tty lock again.
    # Now, we should have a final resumption in the root plus a possible
    # second entry by `bp_forever`.

    child.sendline('c')
    child.expect(r"\(Pdb\+\+\)")
    before = str(child.before.decode())

    assert next_msg in before

    # XXX: hooray the root clobbering the child here was fixed!
    # IMO, this demonstrates the true power of SC system design.

    # now the root actor won't clobber the bp_forever child
    # during it's first access to the debug lock, but will instead
    # wait for the lock to release, by the edge triggered
    # ``_debug.Lock.no_remote_has_tty`` event before sending cancel messages
    # (via portals) to its underlings B)

    # at some point here there should have been some warning msg from
    # the root announcing it avoided a clobber of the child's lock, but
    # it seems unreliable in testing here to gnab it:
    # assert "in use by child ('bp_forever'," in before

    if ctlc:
        do_ctlc(child)

    # wait for final error in root
    while True:

        child.sendline('c')
        child.expect(r"\(Pdb\+\+\)")
        before = str(child.before.decode())
        try:

            # root error should be packed as remote error
            assert "_exceptions.RemoteActorError: ('name_error'" in before
            break

        except AssertionError:
            assert bp_forever_msg in before

        if ctlc:
            do_ctlc(child)

    try:
        child.sendline('c')
        child.expect(pexpect.EOF)

    except TIMEOUT:
        # Failed to exit using continue..?
        child.sendline('q')
        child.expect(pexpect.EOF)


def test_multi_subactors_root_errors(
    spawn,
    ctlc: bool
):
    '''
    Multiple subactors, both erroring and breakpointing as well as
    a nested subactor erroring.

    '''
    child = spawn('multi_subactor_root_errors')

    # scan for the pdbpp prompt
    child.expect(r"\(Pdb\+\+\)")

    # at most one subactor should attach before the root is cancelled
    before = str(child.before.decode())
    assert "NameError: name 'doggypants' is not defined" in before

    if ctlc:
        do_ctlc(child)

    # continue again to catch 2nd name error from
    # actor 'name_error_1' (which is 2nd depth).
    child.sendline('c')
    try:
        child.expect(r"\(Pdb\+\+\)")
    except TIMEOUT:
        child.sendline('')

    # XXX: lol honestly no idea why CI is cuck but
    # seems like this likely falls into our unhandled nested
    # case and isn't working in that env due to raciness..
    name = 'name_error' if ctlc else 'name_error_1'
    assert_before(child, [
        f"Attaching to pdb in crashed actor: ('{name}'",
        "NameError",
    ])

    if ctlc:
        do_ctlc(child)

    child.sendline('c')
    child.expect(r"\(Pdb\+\+\)")
    assert_before(child, [
        "Attaching to pdb in crashed actor: ('spawn_error'",
        # boxed error from previous step
        "RemoteActorError: ('name_error_1'",
        "NameError",
    ])

    if ctlc:
        do_ctlc(child)

    child.sendline('c')
    child.expect(r"\(Pdb\+\+\)")
    assert_before(child, [
        "Attaching to pdb in crashed actor: ('root'",
        # boxed error from previous step
        "RemoteActorError: ('name_error'",
        "NameError",
    ])

    # warnings assert we probably don't need
    # assert "Cancelling nursery in ('spawn_error'," in before

    if ctlc:
        do_ctlc(child)

    # continue again
    child.sendline('c')
    child.expect(pexpect.EOF)

    before = str(child.before.decode())
    # error from root actor and root task that created top level nursery
    assert "AssertionError" in before


def test_multi_nested_subactors_error_through_nurseries(
    spawn,

    # TODO: address debugger issue for nested tree:
    # <issuelink>
    # ctlc: bool,
):
    """Verify deeply nested actors that error trigger debugger entries
    at each actor nurserly (level) all the way up the tree.

    """
    # NOTE: previously, inside this script was a bug where if the
    # parent errors before a 2-levels-lower actor has released the lock,
    # the parent tries to cancel it but it's stuck in the debugger?
    # A test (below) has now been added to explicitly verify this is
    # fixed.

    child = spawn('multi_nested_subactors_error_up_through_nurseries')

    timed_out_early: bool = False

    for i in range(12):
        try:
            child.expect(r"\(Pdb\+\+\)")
            child.sendline('c')
            time.sleep(0.1)

        except EOF:

            # race conditions on how fast the continue is sent?
            print(f"Failed early on {i}?")
            timed_out_early = True
            break
    else:
        child.expect(pexpect.EOF)

    if not timed_out_early:
        before = str(child.before.decode())
        assert "NameError" in before


@pytest.mark.timeout(15)
def test_root_nursery_cancels_before_child_releases_tty_lock(
    spawn,
    start_method,
    ctlc: bool,
):
    """Test that when the root sends a cancel message before a nested
    child has unblocked (which can happen when it has the tty lock and
    is engaged in pdb) it is indeed cancelled after exiting the debugger.
    """
    timed_out_early = False

    child = spawn('root_cancelled_but_child_is_in_tty_lock')

    child.expect(r"\(Pdb\+\+\)")

    before = str(child.before.decode())
    assert "NameError: name 'doggypants' is not defined" in before
    assert "tractor._exceptions.RemoteActorError: ('name_error'" not in before
    time.sleep(0.5)

    if ctlc:
        do_ctlc(child)

    child.sendline('c')

    for i in range(4):
        time.sleep(0.5)
        try:
            child.expect(r"\(Pdb\+\+\)")

        except (
            EOF,
            TIMEOUT,
        ):
            # races all over..

            print(f"Failed early on {i}?")
            before = str(child.before.decode())

            timed_out_early = True

            # race conditions on how fast the continue is sent?
            break

        before = str(child.before.decode())
        assert "NameError: name 'doggypants' is not defined" in before

        if ctlc:
            do_ctlc(child)

        child.sendline('c')
        time.sleep(0.1)

    for i in range(3):
        try:
            child.expect(pexpect.EOF)
            break
        except TIMEOUT:
            child.sendline('c')
            time.sleep(0.1)
            print('child was able to grab tty lock again?')
    else:
        child.sendline('q')
        child.expect(pexpect.EOF)

    if not timed_out_early:

        before = str(child.before.decode())
        assert "tractor._exceptions.RemoteActorError: ('spawner0'" in before
        assert "tractor._exceptions.RemoteActorError: ('name_error'" in before
        assert "NameError: name 'doggypants' is not defined" in before


def test_root_cancels_child_context_during_startup(
    spawn,
    ctlc: bool,
):
    '''Verify a fast fail in the root doesn't lock up the child reaping
    and all while using the new context api.

    '''
    child = spawn('fast_error_in_root_after_spawn')

    child.expect(r"\(Pdb\+\+\)")

    before = str(child.before.decode())
    assert "AssertionError" in before

    if ctlc:
        do_ctlc(child)

    child.sendline('c')
    child.expect(pexpect.EOF)


def test_different_debug_mode_per_actor(
    spawn,
    ctlc: bool,
):
    child = spawn('per_actor_debug')
    child.expect(r"\(Pdb\+\+\)")

    # only one actor should enter the debugger
    before = str(child.before.decode())
    assert "Attaching to pdb in crashed actor: ('debugged_boi'" in before
    assert "RuntimeError" in before

    if ctlc:
        do_ctlc(child)

    child.sendline('c')
    child.expect(pexpect.EOF)

    before = str(child.before.decode())

    # NOTE: this debugged actor error currently WON'T show up since the
    # root will actually cancel and terminate the nursery before the error
    # msg reported back from the debug mode actor is processed.
    # assert "tractor._exceptions.RemoteActorError: ('debugged_boi'" in before

    assert "tractor._exceptions.RemoteActorError: ('crash_boi'" in before

    # the crash boi should not have made a debugger request but
    # instead crashed completely
    assert "tractor._exceptions.RemoteActorError: ('crash_boi'" in before
    assert "RuntimeError" in before