test_resolver.py

from typing import Set

import pytest

from arango.resolver import (
    FallbackHostResolver,
    PeriodicHostResolver,
    RandomHostResolver,
    RoundRobinHostResolver,
    SingleHostResolver,
)


def test_bad_resolver():
    with pytest.raises(ValueError):
        RandomHostResolver(3, 2)


def test_resolver_single_host():
    resolver = SingleHostResolver()
    for _ in range(20):
        assert resolver.get_host_index() == 0


def test_resolver_random_host():
    resolver = RandomHostResolver(10)
    for _ in range(20):
        assert 0 <= resolver.get_host_index() < 10

    resolver = RandomHostResolver(3)
    indexes_to_filter: Set[int] = set()

    index_a = resolver.get_host_index()
    indexes_to_filter.add(index_a)

    index_b = resolver.get_host_index(indexes_to_filter)
    indexes_to_filter.add(index_b)
    assert index_b != index_a

    index_c = resolver.get_host_index(indexes_to_filter)
    indexes_to_filter.clear()
    indexes_to_filter.add(index_c)
    assert index_c not in [index_a, index_b]


def test_resolver_round_robin():
    resolver = RoundRobinHostResolver(10)
    assert resolver.get_host_index() == 0
    assert resolver.get_host_index() == 1
    assert resolver.get_host_index() == 2
    assert resolver.get_host_index() == 3
    assert resolver.get_host_index() == 4
    assert resolver.get_host_index() == 5
    assert resolver.get_host_index() == 6
    assert resolver.get_host_index() == 7
    assert resolver.get_host_index() == 8
    assert resolver.get_host_index() == 9
    assert resolver.get_host_index() == 0


def test_resolver_periodic():
    resolver = PeriodicHostResolver(3, requests_period=3)
    assert resolver.get_host_index() == 0
    assert resolver.get_host_index() == 0
    assert resolver.get_host_index() == 1
    assert resolver.get_host_index() == 1
    assert resolver.get_host_index() == 1
    assert resolver.get_host_index() == 2
    assert resolver.get_host_index() == 2
    assert resolver.get_host_index() == 2
    assert resolver.get_host_index() == 0
    assert resolver.get_host_index() == 0
    assert resolver.get_host_index({0}) == 1
    assert resolver.get_host_index() == 1


def test_resolver_fallback():
    resolver = FallbackHostResolver(4)
    assert resolver.get_host_index() == 0
    assert resolver.get_host_index() == 0
    assert resolver.get_host_index({0, 1, 3}) == 2
    assert resolver.get_host_index({1, 2, 3}) == 0
    assert resolver.get_host_index({0}) == 1
    assert resolver.get_host_index({0}) == 1
    assert resolver.get_host_index() == 1