rust-vmm-ci/integration_tests/test_coverage.py

# Copyright 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
# SPDX-License-Identifier: Apache-2.0
"""Test the coverage and update the threshold when coverage is increased."""

import json
import os
import re
import shutil
import subprocess
import platform
import pytest

from utils import get_repo_root_path


def get_coverage_config_path():
    machine = platform.machine()
    target_file = f"coverage_config_{machine}.json"
    # We use a breadth-first search to guarantee that the config file
    # belongs to the crate that is being tested. Otherwise we might end
    # up wrongfully using the config file in the rust-vmm-ci submodule.
    # os.walkdir() offers a depth-first search and couldn't be used here.
    dirs = [os.getcwd()]
    while len(dirs):
        nextDirs = []
        for dir in dirs:
            for file in os.listdir(dir):
                file_path = os.path.join(dir, file)
                if os.path.isdir(file_path):
                    nextDirs.append(file_path)
                elif file == target_file:
                    return file_path
        dirs = nextDirs


REPO_ROOT_PATH = get_repo_root_path()
COVERAGE_CONFIG_PATH = get_coverage_config_path()


def _read_test_config():
    """
    Reads the config of the coverage for the repository being tested.

    Returns a JSON object with the configuration.
    """
    coverage_config = {}
    with open(COVERAGE_CONFIG_PATH) as config_file:
        coverage_config = json.load(config_file)

    assert "coverage_score" in coverage_config
    assert "exclude_path" in coverage_config
    assert "crate_features" in coverage_config

    return coverage_config


def _write_coverage_config(coverage_config):
    """Updates the coverage config file as per `coverage_config`"""
    with open(COVERAGE_CONFIG_PATH, 'w') as outfile:
        json.dump(coverage_config, outfile)


def _get_current_coverage(coverage_config, no_cleanup):
    """Helper function that returns the coverage computed with kcov."""
    kcov_output_dir = os.path.join(REPO_ROOT_PATH, "kcov_output")

    # By default the build output for kcov and unit tests are both in the debug
    # directory. This causes some linker errors that I haven't investigated.
    # Error: error: linking with `cc` failed: exit code: 1
    # An easy fix is to have separate build directories for kcov & unit tests.
    kcov_build_dir = os.path.join(REPO_ROOT_PATH, "kcov_build")

    # Remove kcov output and build directory to be sure we are always working
    # on a clean environment.
    shutil.rmtree(kcov_output_dir, ignore_errors=True)
    shutil.rmtree(kcov_build_dir, ignore_errors=True)

    exclude_pattern = (
        '${CARGO_HOME:-$HOME/.cargo/},'
        'usr/lib/,'
        'lib/'
    )
    exclude_region = "'mod tests {'"
    additional_exclude_path = coverage_config["exclude_path"]
    if additional_exclude_path:
        exclude_pattern += ',' + additional_exclude_path

    additional_kcov_param = ''
    crate_features = coverage_config["crate_features"]
    if crate_features:
        additional_kcov_param += '--features=' + crate_features

    kcov_cmd = "CARGO_TARGET_DIR={} cargo kcov {} --all " \
               "--output {} -- " \
               "--exclude-region={} " \
               "--exclude-pattern={} " \
               "--verify".format(
                   kcov_build_dir,
                   additional_kcov_param,
                   kcov_output_dir,
                   exclude_region,
                   exclude_pattern
               )

    # Pytest closes stdin by default, but some tests might need it to be open.
    # In the future, should the need arise, we can feed custom data to stdin.
    subprocess.run(kcov_cmd, shell=True, check=True, input=b'')

    # Read the coverage reported by kcov.
    coverage_file = os.path.join(kcov_output_dir, 'index.js')
    with open(coverage_file) as cov_output:
        coverage = float(re.findall(
            r'"covered":"(\d+\.\d)"',
            cov_output.read()
        )[0])

    # Remove coverage related directories.
    # If user provided `--no-cleanup` flag, `kcov_output_dir`
    # should not be removed.
    if not no_cleanup:
        shutil.rmtree(kcov_output_dir, ignore_errors=True)
    shutil.rmtree(kcov_build_dir, ignore_errors=True)

    return coverage


def test_coverage(profile, no_cleanup):
    coverage_config = _read_test_config()
    current_coverage = _get_current_coverage(coverage_config, no_cleanup)
    previous_coverage = coverage_config["coverage_score"]
    if previous_coverage < current_coverage:
        if profile == pytest.profile_ci:
            # In the CI Profile we expect the coverage to be manually updated.
            assert False,\
                "Coverage is increased from {} to {}. "\
                "Please update the coverage in coverage_config_{}.json."\
                .format(
                    previous_coverage,
                    current_coverage,
                    platform.machine()
                )
        elif profile == pytest.profile_devel:
            coverage_config["coverage_score"] = current_coverage
            _write_coverage_config(coverage_config)
        else:
            # This should never happen because pytest should only accept
            # the valid test profiles specified with `choices` in
            # `pytest_addoption`.
            assert False, "Invalid test profile."
    elif previous_coverage > current_coverage:
        diff = float(previous_coverage - current_coverage)
        assert False, "Coverage drops by {:.2f}%. Please add unit tests for " \
                      "the uncovered lines.".format(diff)