plugin.py

import os, hashlib


class CircleCIError(Exception):
    """Raised for problems running the CirleCI py.test plugin"""


def read_circleci_env_variables():
    """Read and convert CIRCLE_* environment variables"""
    circle_node_total = int(os.environ.get("CIRCLE_NODE_TOTAL", "1").strip() or "1")
    circle_node_index = int(os.environ.get("CIRCLE_NODE_INDEX", "0").strip() or "0")

    if circle_node_index >= circle_node_total:
        raise CircleCIError("CIRCLE_NODE_INDEX={} >= CIRCLE_NODE_TOTAL={}, should be less".format(circle_node_index, circle_node_total))

    return (circle_node_total, circle_node_index)


def pytest_report_header(config):
    """Add CircleCI information to report"""
    circle_node_total, circle_node_index = read_circleci_env_variables()
    return "CircleCI total nodes: {}, this node index: {}".format(circle_node_total, circle_node_index)


def pytest_collection_modifyitems(session, config, items):
    """
    Use CircleCI env vars to determine which tests to run

    - CIRCLE_NODE_TOTAL indicates total number of nodes tests are running on
    - CIRCLE_NODE_INDEX indicates which node this is

    Will run a subset of tests based on the node index.

    """
    circle_node_total, circle_node_index = read_circleci_env_variables()
    deselected = []
    for index, item in enumerate(list(items)):
        item_location = ':'.join(map(str, item.location)).encode('utf-8')
        item_hash = int(hashlib.sha1(item_location).hexdigest(), 16)
        if (item_hash % circle_node_total) != circle_node_index:
            deselected.append(item)
            items.remove(item)
    config.hook.pytest_deselected(items=deselected)