test_sample_rand.py

import decimal
from decimal import Inexact, FloatOperation
from unittest import mock

import pytest

import sentry_sdk
from sentry_sdk.tracing_utils import Baggage


@pytest.mark.parametrize("sample_rand", (0.0, 0.25, 0.5, 0.75))
@pytest.mark.parametrize("sample_rate", (0.0, 0.25, 0.5, 0.75, 1.0))
def test_deterministic_sampled(sentry_init, capture_events, sample_rate, sample_rand):
    """
    Test that sample_rand is generated on new traces, that it is used to
    make the sampling decision, and that it is included in the transaction's
    baggage.
    """
    sentry_init(traces_sample_rate=sample_rate)
    events = capture_events()

    with mock.patch(
        "sentry_sdk.tracing_utils.Random.uniform", return_value=sample_rand
    ):
        with sentry_sdk.start_transaction() as transaction:
            assert (
                transaction.get_baggage().sentry_items["sample_rand"]
                == f"{sample_rand:.6f}"  # noqa: E231
            )

    # Transaction event captured if sample_rand < sample_rate, indicating that
    # sample_rand is used to make the sampling decision.
    assert len(events) == int(sample_rand < sample_rate)


@pytest.mark.parametrize("sample_rand", (0.0, 0.25, 0.5, 0.75))
@pytest.mark.parametrize("sample_rate", (0.0, 0.25, 0.5, 0.75, 1.0))
def test_transaction_uses_incoming_sample_rand(
    sentry_init, capture_events, sample_rate, sample_rand
):
    """
    Test that the transaction uses the sample_rand value from the incoming baggage.
    """
    baggage = Baggage(sentry_items={"sample_rand": f"{sample_rand:.6f}"})  # noqa: E231

    sentry_init(traces_sample_rate=sample_rate)
    events = capture_events()

    with sentry_sdk.start_transaction(baggage=baggage) as transaction:
        assert (
            transaction.get_baggage().sentry_items["sample_rand"]
            == f"{sample_rand:.6f}"  # noqa: E231
        )

    # Transaction event captured if sample_rand < sample_rate, indicating that
    # sample_rand is used to make the sampling decision.
    assert len(events) == int(sample_rand < sample_rate)


def test_decimal_context(sentry_init, capture_events):
    """
    Ensure that having a user altered decimal context with a precision below 6
    does not cause an InvalidOperation exception.
    """
    sentry_init(traces_sample_rate=1.0)
    events = capture_events()

    old_prec = decimal.getcontext().prec
    old_inexact = decimal.getcontext().traps[Inexact]
    old_float_operation = decimal.getcontext().traps[FloatOperation]

    decimal.getcontext().prec = 2
    decimal.getcontext().traps[Inexact] = True
    decimal.getcontext().traps[FloatOperation] = True

    try:
        with mock.patch(
            "sentry_sdk.tracing_utils.Random.uniform", return_value=0.123456789
        ):
            with sentry_sdk.start_transaction() as transaction:
                assert (
                    transaction.get_baggage().sentry_items["sample_rand"] == "0.123456"
                )
    finally:
        decimal.getcontext().prec = old_prec
        decimal.getcontext().traps[Inexact] = old_inexact
        decimal.getcontext().traps[FloatOperation] = old_float_operation

    assert len(events) == 1