test_retry.py

# Copyright 2017 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import datetime
import itertools
import re

try:
    from unittest import mock
except:
    import mock
import pytest
import requests.exceptions

from google.api_core import exceptions
from google.api_core import retry
from google.auth import exceptions as auth_exceptions


def test_if_exception_type():
    predicate = retry.if_exception_type(ValueError)

    assert predicate(ValueError())
    assert not predicate(TypeError())


def test_if_exception_type_multiple():
    predicate = retry.if_exception_type(ValueError, TypeError)

    assert predicate(ValueError())
    assert predicate(TypeError())
    assert not predicate(RuntimeError())


def test_if_transient_error():
    assert retry.if_transient_error(exceptions.InternalServerError(""))
    assert retry.if_transient_error(exceptions.TooManyRequests(""))
    assert retry.if_transient_error(exceptions.ServiceUnavailable(""))
    assert retry.if_transient_error(requests.exceptions.ConnectionError(""))
    assert retry.if_transient_error(auth_exceptions.TransportError(""))
    assert not retry.if_transient_error(exceptions.InvalidArgument(""))


# Make uniform return half of its maximum, which will be the calculated
# sleep time.
@mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
def test_exponential_sleep_generator_base_2(uniform):
    gen = retry.exponential_sleep_generator(1, 60, multiplier=2)

    result = list(itertools.islice(gen, 8))
    assert result == [1, 2, 4, 8, 16, 32, 60, 60]


@mock.patch("time.sleep", autospec=True)
@mock.patch(
    "google.api_core.datetime_helpers.utcnow",
    return_value=datetime.datetime.min,
    autospec=True,
)
def test_retry_target_success(utcnow, sleep):
    predicate = retry.if_exception_type(ValueError)
    call_count = [0]

    def target():
        call_count[0] += 1
        if call_count[0] < 3:
            raise ValueError()
        return 42

    result = retry.retry_target(target, predicate, range(10), None)

    assert result == 42
    assert call_count[0] == 3
    sleep.assert_has_calls([mock.call(0), mock.call(1)])


@mock.patch("time.sleep", autospec=True)
@mock.patch(
    "google.api_core.datetime_helpers.utcnow",
    return_value=datetime.datetime.min,
    autospec=True,
)
def test_retry_target_w_on_error(utcnow, sleep):
    predicate = retry.if_exception_type(ValueError)
    call_count = {"target": 0}
    to_raise = ValueError()

    def target():
        call_count["target"] += 1
        if call_count["target"] < 3:
            raise to_raise
        return 42

    on_error = mock.Mock()

    result = retry.retry_target(target, predicate, range(10), None, on_error=on_error)

    assert result == 42
    assert call_count["target"] == 3

    on_error.assert_has_calls([mock.call(to_raise), mock.call(to_raise)])
    sleep.assert_has_calls([mock.call(0), mock.call(1)])


@mock.patch("time.sleep", autospec=True)
@mock.patch(
    "google.api_core.datetime_helpers.utcnow",
    return_value=datetime.datetime.min,
    autospec=True,
)
def test_retry_target_non_retryable_error(utcnow, sleep):
    predicate = retry.if_exception_type(ValueError)
    exception = TypeError()
    target = mock.Mock(side_effect=exception)

    with pytest.raises(TypeError) as exc_info:
        retry.retry_target(target, predicate, range(10), None)

    assert exc_info.value == exception
    sleep.assert_not_called()


@mock.patch("time.sleep", autospec=True)
@mock.patch("google.api_core.datetime_helpers.utcnow", autospec=True)
def test_retry_target_deadline_exceeded(utcnow, sleep):
    predicate = retry.if_exception_type(ValueError)
    exception = ValueError("meep")
    target = mock.Mock(side_effect=exception)
    # Setup the timeline so that the first call takes 5 seconds but the second
    # call takes 6, which puts the retry over the deadline.
    utcnow.side_effect = [
        # The first call to utcnow establishes the start of the timeline.
        datetime.datetime.min,
        datetime.datetime.min + datetime.timedelta(seconds=5),
        datetime.datetime.min + datetime.timedelta(seconds=11),
    ]

    with pytest.raises(exceptions.RetryError) as exc_info:
        retry.retry_target(target, predicate, range(10), deadline=10)

    assert exc_info.value.cause == exception
    assert exc_info.match("Deadline of 10.0s exceeded")
    assert exc_info.match("last exception: meep")
    assert target.call_count == 2


def test_retry_target_bad_sleep_generator():
    with pytest.raises(ValueError, match="Sleep generator"):
        retry.retry_target(mock.sentinel.target, mock.sentinel.predicate, [], None)


class TestRetry(object):
    def test_constructor_defaults(self):
        retry_ = retry.Retry()
        assert retry_._predicate == retry.if_transient_error
        assert retry_._initial == 1
        assert retry_._maximum == 60
        assert retry_._multiplier == 2
        assert retry_._deadline == 120
        assert retry_._on_error is None
        assert retry_.deadline == 120

    def test_constructor_options(self):
        _some_function = mock.Mock()

        retry_ = retry.Retry(
            predicate=mock.sentinel.predicate,
            initial=1,
            maximum=2,
            multiplier=3,
            deadline=4,
            on_error=_some_function,
        )
        assert retry_._predicate == mock.sentinel.predicate
        assert retry_._initial == 1
        assert retry_._maximum == 2
        assert retry_._multiplier == 3
        assert retry_._deadline == 4
        assert retry_._on_error is _some_function

    def test_with_deadline(self):
        retry_ = retry.Retry(
            predicate=mock.sentinel.predicate,
            initial=1,
            maximum=2,
            multiplier=3,
            deadline=4,
            on_error=mock.sentinel.on_error,
        )
        new_retry = retry_.with_deadline(42)
        assert retry_ is not new_retry
        assert new_retry._deadline == 42

        # the rest of the attributes should remain the same
        assert new_retry._predicate is retry_._predicate
        assert new_retry._initial == retry_._initial
        assert new_retry._maximum == retry_._maximum
        assert new_retry._multiplier == retry_._multiplier
        assert new_retry._on_error is retry_._on_error

    def test_with_predicate(self):
        retry_ = retry.Retry(
            predicate=mock.sentinel.predicate,
            initial=1,
            maximum=2,
            multiplier=3,
            deadline=4,
            on_error=mock.sentinel.on_error,
        )
        new_retry = retry_.with_predicate(mock.sentinel.predicate)
        assert retry_ is not new_retry
        assert new_retry._predicate == mock.sentinel.predicate

        # the rest of the attributes should remain the same
        assert new_retry._deadline == retry_._deadline
        assert new_retry._initial == retry_._initial
        assert new_retry._maximum == retry_._maximum
        assert new_retry._multiplier == retry_._multiplier
        assert new_retry._on_error is retry_._on_error

    def test_with_delay_noop(self):
        retry_ = retry.Retry(
            predicate=mock.sentinel.predicate,
            initial=1,
            maximum=2,
            multiplier=3,
            deadline=4,
            on_error=mock.sentinel.on_error,
        )
        new_retry = retry_.with_delay()
        assert retry_ is not new_retry
        assert new_retry._initial == retry_._initial
        assert new_retry._maximum == retry_._maximum
        assert new_retry._multiplier == retry_._multiplier

    def test_with_delay(self):
        retry_ = retry.Retry(
            predicate=mock.sentinel.predicate,
            initial=1,
            maximum=2,
            multiplier=3,
            deadline=4,
            on_error=mock.sentinel.on_error,
        )
        new_retry = retry_.with_delay(initial=5, maximum=6, multiplier=7)
        assert retry_ is not new_retry
        assert new_retry._initial == 5
        assert new_retry._maximum == 6
        assert new_retry._multiplier == 7

        # the rest of the attributes should remain the same
        assert new_retry._deadline == retry_._deadline
        assert new_retry._predicate is retry_._predicate
        assert new_retry._on_error is retry_._on_error

    def test_with_delay_partial_options(self):
        retry_ = retry.Retry(
            predicate=mock.sentinel.predicate,
            initial=1,
            maximum=2,
            multiplier=3,
            deadline=4,
            on_error=mock.sentinel.on_error,
        )
        new_retry = retry_.with_delay(initial=4)
        assert retry_ is not new_retry
        assert new_retry._initial == 4
        assert new_retry._maximum == 2
        assert new_retry._multiplier == 3

        new_retry = retry_.with_delay(maximum=4)
        assert retry_ is not new_retry
        assert new_retry._initial == 1
        assert new_retry._maximum == 4
        assert new_retry._multiplier == 3

        new_retry = retry_.with_delay(multiplier=4)
        assert retry_ is not new_retry
        assert new_retry._initial == 1
        assert new_retry._maximum == 2
        assert new_retry._multiplier == 4

        # the rest of the attributes should remain the same
        assert new_retry._deadline == retry_._deadline
        assert new_retry._predicate is retry_._predicate
        assert new_retry._on_error is retry_._on_error

    def test___str__(self):
        def if_exception_type(exc):
            return bool(exc)  # pragma: NO COVER

        # Explicitly set all attributes as changed Retry defaults should not
        # cause this test to start failing.
        retry_ = retry.Retry(
            predicate=if_exception_type,
            initial=1.0,
            maximum=60.0,
            multiplier=2.0,
            deadline=120.0,
            on_error=None,
        )
        assert re.match(
            (
                r"<Retry predicate=<function.*?if_exception_type.*?>, "
                r"initial=1.0, maximum=60.0, multiplier=2.0, deadline=120.0, "
                r"on_error=None>"
            ),
            str(retry_),
        )

    @mock.patch("time.sleep", autospec=True)
    def test___call___and_execute_success(self, sleep):
        retry_ = retry.Retry()
        target = mock.Mock(spec=["__call__"], return_value=42)
        # __name__ is needed by functools.partial.
        target.__name__ = "target"

        decorated = retry_(target)
        target.assert_not_called()

        result = decorated("meep")

        assert result == 42
        target.assert_called_once_with("meep")
        sleep.assert_not_called()

    # Make uniform return half of its maximum, which is the calculated sleep time.
    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
    @mock.patch("time.sleep", autospec=True)
    def test___call___and_execute_retry(self, sleep, uniform):

        on_error = mock.Mock(spec=["__call__"], side_effect=[None])
        retry_ = retry.Retry(predicate=retry.if_exception_type(ValueError))

        target = mock.Mock(spec=["__call__"], side_effect=[ValueError(), 42])
        # __name__ is needed by functools.partial.
        target.__name__ = "target"

        decorated = retry_(target, on_error=on_error)
        target.assert_not_called()

        result = decorated("meep")

        assert result == 42
        assert target.call_count == 2
        target.assert_has_calls([mock.call("meep"), mock.call("meep")])
        sleep.assert_called_once_with(retry_._initial)
        assert on_error.call_count == 1

    # Make uniform return half of its maximum, which is the calculated sleep time.
    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
    @mock.patch("time.sleep", autospec=True)
    def test___call___and_execute_retry_hitting_deadline(self, sleep, uniform):

        on_error = mock.Mock(spec=["__call__"], side_effect=[None] * 10)
        retry_ = retry.Retry(
            predicate=retry.if_exception_type(ValueError),
            initial=1.0,
            maximum=1024.0,
            multiplier=2.0,
            deadline=9.9,
        )

        utcnow = datetime.datetime.utcnow()
        utcnow_patcher = mock.patch(
            "google.api_core.datetime_helpers.utcnow", return_value=utcnow
        )

        target = mock.Mock(spec=["__call__"], side_effect=[ValueError()] * 10)
        # __name__ is needed by functools.partial.
        target.__name__ = "target"

        decorated = retry_(target, on_error=on_error)
        target.assert_not_called()

        with utcnow_patcher as patched_utcnow:
            # Make sure that calls to fake time.sleep() also advance the mocked
            # time clock.
            def increase_time(sleep_delay):
                patched_utcnow.return_value += datetime.timedelta(seconds=sleep_delay)
            sleep.side_effect = increase_time

            with pytest.raises(exceptions.RetryError):
                decorated("meep")

        assert target.call_count == 5
        target.assert_has_calls([mock.call("meep")] * 5)
        assert on_error.call_count == 5

        # check the delays
        assert sleep.call_count == 4  # once between each successive target calls
        last_wait = sleep.call_args.args[0]
        total_wait = sum(call_args.args[0] for call_args in sleep.call_args_list)

        assert last_wait == 2.9   # and not 8.0, because the last delay was shortened
        assert total_wait == 9.9  # the same as the deadline

    @mock.patch("time.sleep", autospec=True)
    def test___init___without_retry_executed(self, sleep):
        _some_function = mock.Mock()

        retry_ = retry.Retry(
            predicate=retry.if_exception_type(ValueError), on_error=_some_function
        )
        # check the proper creation of the class
        assert retry_._on_error is _some_function

        target = mock.Mock(spec=["__call__"], side_effect=[42])
        # __name__ is needed by functools.partial.
        target.__name__ = "target"

        wrapped = retry_(target)

        result = wrapped("meep")

        assert result == 42
        target.assert_called_once_with("meep")
        sleep.assert_not_called()
        _some_function.assert_not_called()

    # Make uniform return half of its maximum, which is the calculated sleep time.
    @mock.patch("random.uniform", autospec=True, side_effect=lambda m, n: n / 2.0)
    @mock.patch("time.sleep", autospec=True)
    def test___init___when_retry_is_executed(self, sleep, uniform):
        _some_function = mock.Mock()

        retry_ = retry.Retry(
            predicate=retry.if_exception_type(ValueError), on_error=_some_function
        )
        # check the proper creation of the class
        assert retry_._on_error is _some_function

        target = mock.Mock(
            spec=["__call__"], side_effect=[ValueError(), ValueError(), 42]
        )
        # __name__ is needed by functools.partial.
        target.__name__ = "target"

        wrapped = retry_(target)
        target.assert_not_called()

        result = wrapped("meep")

        assert result == 42
        assert target.call_count == 3
        assert _some_function.call_count == 2
        target.assert_has_calls([mock.call("meep"), mock.call("meep")])
        sleep.assert_any_call(retry_._initial)