taar/tests/test_cache.py

from taar.cache import Clock, JSONCache
import time
import pytest
from taar.context import Context


EXPECTED_JSON = {"foo": 42}
EXPECTED_S3_JSON = {"foo": "bar"}


class MockUtils:
    def __init__(self):
        self._fetch_count = 0
        self._get_count = 0

    def fetch_json(self, url):
        self._fetch_count += 1
        return EXPECTED_JSON

    def get_s3_json_content(self, s3_bucket, s3_key):
        self._get_count += 1
        return EXPECTED_S3_JSON


def test_clock():
    cl = Clock()
    assert time.time() == pytest.approx(cl.time(), 0.1)


def test_fetch_json():
    """ Just test a URL that we know will fail """
    ctx = Context()
    ctx['utils'] = utils = MockUtils()
    ctx['clock'] = Clock()
    cache = JSONCache(ctx)
    jdata = cache.fetch_json("http://127.0.0.1:9001/some-nonexistant-url-foo.json")
    assert jdata == EXPECTED_JSON

    assert utils._fetch_count == 1
    for i in range(10):
        cache.fetch_json("http://127.0.0.1:9001/some-nonexistant-url-foo.json")
    assert utils._fetch_count == 1


def test_get_s3_json_content():
    """ Just test an S3 bucket and key that doesn't exist """
    ctx = Context()
    ctx['utils'] = utils = MockUtils()
    ctx['clock'] = Clock()
    cache = JSONCache(ctx)
    jdata = cache.get_s3_json_content("taar_not_my_bucket", "this/is/not/a/valid/path")
    assert jdata == EXPECTED_S3_JSON

    assert utils._get_count == 1
    for i in range(10):
        cache.get_s3_json_content("taar_not_my_bucket", "this/is/not/a/valid/path")
    assert utils._get_count == 1


def test_expiry():
    """ Just test a URL that we know will fail """
    class MockClock:
        def __init__(self):
            self._now = 100

        def time(self):
            return self._now

    ctx = Context()
    utils = MockUtils()
    ctx['utils'] = utils
    ctx['clock'] = MockClock()

    cache = JSONCache(ctx)

    cache._ttl = 0  # Set TTL to nothing
    cache.refresh_expiry()

    jdata = cache.fetch_json("http://127.0.0.1:9001/some-nonexistant-url-foo.json")
    assert jdata == EXPECTED_JSON
    jdata = cache.get_s3_json_content("taar_not_my_bucket", "this/is/not/a/valid/path")
    assert jdata == EXPECTED_S3_JSON

    assert utils._get_count == 1
    assert utils._fetch_count == 1

    for i in range(10):
        cache.fetch_json("http://127.0.0.1:9001/some-nonexistant-url-foo.json")
        cache.get_s3_json_content("taar_not_my_bucket", "this/is/not/a/valid/path")

    # Cache expires each time
    assert utils._get_count == 11
    assert utils._fetch_count == 11