ansible/test/runner/lib/executor.py

"""Execute Ansible tests."""

from __future__ import absolute_import, print_function

import json
import os
import re
import tempfile
import time
import textwrap
import functools
import shutil
import stat
import random
import string
import atexit

import lib.pytar
import lib.thread

from lib.core_ci import (
    AnsibleCoreCI,
    SshKey,
)

from lib.manage_ci import (
    ManageWindowsCI,
    ManageNetworkCI,
)

from lib.cloud import (
    cloud_filter,
    cloud_init,
    get_cloud_environment,
    get_cloud_platforms,
)

from lib.util import (
    EnvironmentConfig,
    ApplicationWarning,
    ApplicationError,
    SubprocessError,
    MissingEnvironmentVariable,
    display,
    run_command,
    common_environment,
    remove_tree,
    make_dirs,
    is_shippable,
    is_binary_file,
    find_executable,
    raw_command,
)

from lib.test import (
    TestConfig,
)

from lib.ansible_util import (
    ansible_environment,
)

from lib.target import (
    IntegrationTarget,
    walk_external_targets,
    walk_internal_targets,
    walk_posix_integration_targets,
    walk_network_integration_targets,
    walk_windows_integration_targets,
    walk_units_targets,
    walk_compile_targets,
)

from lib.changes import (
    ShippableChanges,
    LocalChanges,
)

from lib.git import (
    Git,
)

from lib.classification import (
    categorize_changes,
)

from lib.test import (
    TestMessage,
    TestSuccess,
    TestFailure,
    TestSkipped,
)

SUPPORTED_PYTHON_VERSIONS = (
    '2.6',
    '2.7',
    '3.5',
    '3.6',
)

COMPILE_PYTHON_VERSIONS = SUPPORTED_PYTHON_VERSIONS

coverage_path = ''  # pylint: disable=locally-disabled, invalid-name


def check_startup():
    """Checks to perform at startup before running commands."""
    check_legacy_modules()


def check_legacy_modules():
    """Detect conflicts with legacy core/extras module directories to avoid problems later."""
    for directory in 'core', 'extras':
        path = 'lib/ansible/modules/%s' % directory

        for root, _, file_names in os.walk(path):
            if file_names:
                # the directory shouldn't exist, but if it does, it must contain no files
                raise ApplicationError('Files prohibited in "%s". '
                                       'These are most likely legacy modules from version 2.2 or earlier.' % root)


def create_shell_command(command):
    """
    :type command: list[str]
    :rtype: list[str]
    """
    optional_vars = (
        'TERM',
    )

    cmd = ['/usr/bin/env']
    cmd += ['%s=%s' % (var, os.environ[var]) for var in optional_vars if var in os.environ]
    cmd += command

    return cmd


def install_command_requirements(args):
    """
    :type args: EnvironmentConfig
    """
    generate_egg_info(args)

    if not args.requirements:
        return

    packages = []

    if isinstance(args, TestConfig):
        if args.coverage:
            packages.append('coverage')
        if args.junit:
            packages.append('junit-xml')

    extras = []

    if isinstance(args, TestConfig):
        extras += ['cloud.%s' % cp for cp in get_cloud_platforms(args)]

    cmd = generate_pip_install(args.command, packages, extras)

    if not cmd:
        return

    try:
        run_command(args, cmd)
    except SubprocessError as ex:
        if ex.status != 2:
            raise

        # If pip is too old it won't understand the arguments we passed in, so we'll need to upgrade it.

        # Installing "coverage" on ubuntu 16.04 fails with the error:
        # AttributeError: 'Requirement' object has no attribute 'project_name'
        # See: https://bugs.launchpad.net/ubuntu/xenial/+source/python-pip/+bug/1626258
        # Upgrading pip works around the issue.
        run_command(args, ['pip', 'install', '--upgrade', 'pip'])
        run_command(args, cmd)


def generate_egg_info(args):
    """
    :type args: EnvironmentConfig
    """
    if os.path.isdir('lib/ansible.egg-info'):
        return

    run_command(args, ['python', 'setup.py', 'egg_info'], capture=args.verbosity < 3)


def generate_pip_install(command, packages=None, extras=None):
    """
    :type command: str
    :type packages: list[str] | None
    :type extras: list[str] | None
    :rtype: list[str] | None
    """
    constraints = 'test/runner/requirements/constraints.txt'
    requirements = 'test/runner/requirements/%s.txt' % command

    options = []

    requirements_list = [requirements]

    if extras:
        for extra in extras:
            requirements_list.append('test/runner/requirements/%s.%s.txt' % (command, extra))

    for requirements in requirements_list:
        if os.path.exists(requirements) and os.path.getsize(requirements):
            options += ['-r', requirements]

    if packages:
        options += packages

    if not options:
        return None

    return ['pip', 'install', '--disable-pip-version-check', '-c', constraints] + options


def command_shell(args):
    """
    :type args: ShellConfig
    """
    if args.delegate:
        raise Delegate()

    install_command_requirements(args)

    cmd = create_shell_command(['bash', '-i'])
    run_command(args, cmd)


def command_posix_integration(args):
    """
    :type args: PosixIntegrationConfig
    """
    internal_targets = command_integration_filter(args, walk_posix_integration_targets())
    command_integration_filtered(args, internal_targets)


def command_network_integration(args):
    """
    :type args: NetworkIntegrationConfig
    """
    internal_targets = command_integration_filter(args, walk_network_integration_targets())
    platform_targets = set(a for t in internal_targets for a in t.aliases if a.startswith('network/'))

    if args.platform:
        instances = []  # type: list [lib.thread.WrappedThread]

        # generate an ssh key (if needed) up front once, instead of for each instance
        SshKey(args)

        for platform_version in args.platform:
            platform, version = platform_version.split('/', 1)
            platform_target = 'network/%s/' % platform

            if platform_target not in platform_targets and 'network/basics/' not in platform_targets:
                display.warning('Skipping "%s" because selected tests do not target the "%s" platform.' % (
                    platform_version, platform))
                continue

            instance = lib.thread.WrappedThread(functools.partial(network_run, args, platform, version))
            instance.daemon = True
            instance.start()
            instances.append(instance)

        install_command_requirements(args)

        while any(instance.is_alive() for instance in instances):
            time.sleep(1)

        remotes = [instance.wait_for_result() for instance in instances]
        inventory = network_inventory(remotes)

        filename = 'test/integration/inventory.networking'

        display.info('>>> Inventory: %s\n%s' % (filename, inventory.strip()), verbosity=3)

        if not args.explain:
            with open(filename, 'w') as inventory_fd:
                inventory_fd.write(inventory)
    else:
        install_command_requirements(args)

    command_integration_filtered(args, internal_targets)


def network_run(args, platform, version):
    """
    :type args: NetworkIntegrationConfig
    :type platform: str
    :type version: str
    :rtype: AnsibleCoreCI
    """

    core_ci = AnsibleCoreCI(args, platform, version, stage=args.remote_stage)
    core_ci.start()
    core_ci.wait()

    manage = ManageNetworkCI(core_ci)
    manage.wait()

    return core_ci


def network_inventory(remotes):
    """
    :type remotes: list[AnsibleCoreCI]
    :rtype: str
    """
    groups = dict([(remote.platform, []) for remote in remotes])

    for remote in remotes:
        options = dict(
            ansible_host=remote.connection.hostname,
            ansible_user=remote.connection.username,
            ansible_ssh_private_key_file=remote.ssh_key.key,
            ansible_network_os=remote.platform,
            ansible_connection='local'
        )

        groups[remote.platform].append(
            '%s %s' % (
                remote.name.replace('.', '_'),
                ' '.join('%s="%s"' % (k, options[k]) for k in sorted(options)),
            )
        )

    template = ''

    for group in groups:
        hosts = '\n'.join(groups[group])

        template += textwrap.dedent("""
        [%s]
        %s
        """) % (group, hosts)

    inventory = template

    return inventory


def command_windows_integration(args):
    """
    :type args: WindowsIntegrationConfig
    """
    internal_targets = command_integration_filter(args, walk_windows_integration_targets())

    if args.windows:
        instances = []  # type: list [lib.thread.WrappedThread]

        for version in args.windows:
            instance = lib.thread.WrappedThread(functools.partial(windows_run, args, version))
            instance.daemon = True
            instance.start()
            instances.append(instance)

        install_command_requirements(args)

        while any(instance.is_alive() for instance in instances):
            time.sleep(1)

        remotes = [instance.wait_for_result() for instance in instances]
        inventory = windows_inventory(remotes)

        filename = 'test/integration/inventory.winrm'

        display.info('>>> Inventory: %s\n%s' % (filename, inventory.strip()), verbosity=3)

        if not args.explain:
            with open(filename, 'w') as inventory_fd:
                inventory_fd.write(inventory)
    else:
        install_command_requirements(args)

    try:
        command_integration_filtered(args, internal_targets)
    finally:
        pass


def windows_run(args, version):
    """
    :type args: WindowsIntegrationConfig
    :type version: str
    :rtype: AnsibleCoreCI
    """
    core_ci = AnsibleCoreCI(args, 'windows', version, stage=args.remote_stage)
    core_ci.start()
    core_ci.wait()

    manage = ManageWindowsCI(core_ci)
    manage.wait()

    return core_ci


def windows_inventory(remotes):
    """
    :type remotes: list[AnsibleCoreCI]
    :rtype: str
    """
    hosts = []

    for remote in remotes:
        options = dict(
            ansible_host=remote.connection.hostname,
            ansible_user=remote.connection.username,
            ansible_password=remote.connection.password,
            ansible_port=remote.connection.port,
        )

        hosts.append(
            '%s %s' % (
                remote.name.replace('/', '_'),
                ' '.join('%s="%s"' % (k, options[k]) for k in sorted(options)),
            )
        )

    template = """
    [windows]
    %s

    [windows:vars]
    ansible_connection=winrm
    ansible_winrm_server_cert_validation=ignore

    # support winrm connection tests (temporary solution, does not support testing enable/disable of pipelining)
    [winrm:children]
    windows

    # support winrm binary module tests (temporary solution)
    [testhost_binary_modules:children]
    windows
    """

    template = textwrap.dedent(template)
    inventory = template % ('\n'.join(hosts))

    return inventory


def command_integration_filter(args, targets):
    """
    :type args: IntegrationConfig
    :type targets: collections.Iterable[IntegrationTarget]
    :rtype: tuple[IntegrationTarget]
    """
    targets = tuple(targets)
    changes = get_changes_filter(args)
    require = (args.require or []) + changes
    exclude = (args.exclude or [])

    internal_targets = walk_internal_targets(targets, args.include, exclude, require)
    environment_exclude = get_integration_filter(args, internal_targets)

    environment_exclude += cloud_filter(args, internal_targets)

    if environment_exclude:
        exclude += environment_exclude
        internal_targets = walk_internal_targets(targets, args.include, exclude, require)

    if not internal_targets:
        raise AllTargetsSkipped()

    if args.start_at and not any(t.name == args.start_at for t in internal_targets):
        raise ApplicationError('Start at target matches nothing: %s' % args.start_at)

    cloud_init(args, internal_targets)

    if args.delegate:
        raise Delegate(require=changes, exclude=exclude)

    install_command_requirements(args)

    return internal_targets


def command_integration_filtered(args, targets):
    """
    :type args: IntegrationConfig
    :type targets: tuple[IntegrationTarget]
    """
    found = False

    targets_iter = iter(targets)

    test_dir = os.path.expanduser('~/ansible_testing')

    if any('needs/ssh/' in target.aliases for target in targets):
        max_tries = 20
        display.info('SSH service required for tests. Checking to make sure we can connect.')
        for i in range(1, max_tries + 1):
            try:
                run_command(args, ['ssh', '-o', 'BatchMode=yes', 'localhost', 'id'], capture=True)
                display.info('SSH service responded.')
                break
            except SubprocessError:
                if i == max_tries:
                    raise
                seconds = 3
                display.warning('SSH service not responding. Waiting %d second(s) before checking again.' % seconds)
                time.sleep(seconds)

    start_at_task = args.start_at_task

    for target in targets_iter:
        if args.start_at and not found:
            found = target.name == args.start_at

            if not found:
                continue

        tries = 2 if args.retry_on_error else 1
        verbosity = args.verbosity

        cloud_environment = get_cloud_environment(args, target)

        original_environment = EnvironmentDescription()

        display.info('>>> Environment Description\n%s' % original_environment, verbosity=3)

        try:
            while tries:
                tries -= 1

                if not args.explain:
                    # create a fresh test directory for each test target
                    remove_tree(test_dir)
                    make_dirs(test_dir)

                try:
                    if target.script_path:
                        command_integration_script(args, target)
                    else:
                        command_integration_role(args, target, start_at_task)
                        start_at_task = None
                    break
                except SubprocessError:
                    if cloud_environment:
                        cloud_environment.on_failure(target, tries)

                    if not original_environment.validate(target.name, throw=False):
                        raise

                    if not tries:
                        raise

                    display.warning('Retrying test target "%s" with maximum verbosity.' % target.name)
                    display.verbosity = args.verbosity = 6

            original_environment.validate(target.name, throw=True)
        except:
            display.notice('To resume at this test target, use the option: --start-at %s' % target.name)

            next_target = next(targets_iter, None)

            if next_target:
                display.notice('To resume after this test target, use the option: --start-at %s' % next_target.name)

            raise
        finally:
            display.verbosity = args.verbosity = verbosity


def integration_environment(args, target, cmd):
    """
    :type args: IntegrationConfig
    :type target: IntegrationTarget
    :type cmd: list[str]
    :rtype: dict[str, str]
    """
    env = ansible_environment(args)

    integration = dict(
        JUNIT_OUTPUT_DIR=os.path.abspath('test/results/junit'),
        ANSIBLE_CALLBACK_WHITELIST='junit',
    )

    env.update(integration)

    cloud_environment = get_cloud_environment(args, target)

    if cloud_environment:
        cloud_environment.configure_environment(env, cmd)

    return env


def command_integration_script(args, target):
    """
    :type args: IntegrationConfig
    :type target: IntegrationTarget
    """
    display.info('Running %s integration test script' % target.name)

    cmd = ['./%s' % os.path.basename(target.script_path)]

    if args.verbosity:
        cmd.append('-' + ('v' * args.verbosity))

    env = integration_environment(args, target, cmd)
    cwd = target.path

    intercept_command(args, cmd, target_name=target.name, env=env, cwd=cwd)


def command_integration_role(args, target, start_at_task):
    """
    :type args: IntegrationConfig
    :type target: IntegrationTarget
    :type start_at_task: str
    """
    display.info('Running %s integration test role' % target.name)

    vars_file = 'integration_config.yml'

    if isinstance(args, WindowsIntegrationConfig):
        inventory = 'inventory.winrm'
        hosts = 'windows'
        gather_facts = False
    elif isinstance(args, NetworkIntegrationConfig):
        inventory = 'inventory.networking'
        hosts = target.name[:target.name.find('_')]
        gather_facts = False
        if hosts == 'net':
            hosts = 'all'
    else:
        inventory = 'inventory'
        hosts = 'testhost'
        gather_facts = True

        cloud_environment = get_cloud_environment(args, target)

        if cloud_environment:
            hosts = cloud_environment.inventory_hosts or hosts

    playbook = '''
- hosts: %s
  gather_facts: %s
  roles:
    - { role: %s }
    ''' % (hosts, gather_facts, target.name)

    with tempfile.NamedTemporaryFile(dir='test/integration', prefix='%s-' % target.name, suffix='.yml') as pb_fd:
        pb_fd.write(playbook.encode('utf-8'))
        pb_fd.flush()

        filename = os.path.basename(pb_fd.name)

        display.info('>>> Playbook: %s\n%s' % (filename, playbook.strip()), verbosity=3)

        cmd = ['ansible-playbook', filename, '-i', inventory, '-e', '@%s' % vars_file]

        if start_at_task:
            cmd += ['--start-at-task', start_at_task]

        if args.verbosity:
            cmd.append('-' + ('v' * args.verbosity))

        env = integration_environment(args, target, cmd)
        cwd = 'test/integration'

        env['ANSIBLE_ROLES_PATH'] = os.path.abspath('test/integration/targets')

        intercept_command(args, cmd, target_name=target.name, env=env, cwd=cwd)


def command_units(args):
    """
    :type args: UnitsConfig
    """
    changes = get_changes_filter(args)
    require = (args.require or []) + changes
    include, exclude = walk_external_targets(walk_units_targets(), args.include, args.exclude, require)

    if not include:
        raise AllTargetsSkipped()

    if args.delegate:
        raise Delegate(require=changes)

    install_command_requirements(args)

    version_commands = []

    for version in SUPPORTED_PYTHON_VERSIONS:
        # run all versions unless version given, in which case run only that version
        if args.python and version != args.python:
            continue

        env = ansible_environment(args)

        cmd = [
            'pytest',
            '--boxed',
            '-r', 'a',
            '--color',
            'yes' if args.color else 'no',
            '--junit-xml',
            'test/results/junit/python%s-units.xml' % version,
        ]

        if args.collect_only:
            cmd.append('--collect-only')

        if args.verbosity:
            cmd.append('-' + ('v' * args.verbosity))

        if exclude:
            cmd += ['--ignore=%s' % target.path for target in exclude]

        cmd += [target.path for target in include]

        version_commands.append((version, cmd, env))

    for version, command, env in version_commands:
        display.info('Unit test with Python %s' % version)

        try:
            intercept_command(args, command, target_name='units', env=env, python_version=version)
        except SubprocessError as ex:
            # pytest exits with status code 5 when all tests are skipped, which isn't an error for our use case
            if ex.status != 5:
                raise


def command_compile(args):
    """
    :type args: CompileConfig
    """
    changes = get_changes_filter(args)
    require = (args.require or []) + changes
    include, exclude = walk_external_targets(walk_compile_targets(), args.include, args.exclude, require)

    if not include:
        raise AllTargetsSkipped()

    if args.delegate:
        raise Delegate(require=changes)

    install_command_requirements(args)

    total = 0
    failed = []

    for version in COMPILE_PYTHON_VERSIONS:
        # run all versions unless version given, in which case run only that version
        if args.python and version != args.python:
            continue

        display.info('Compile with Python %s' % version)

        result = compile_version(args, version, include, exclude)
        result.write(args)

        total += 1

        if isinstance(result, TestFailure):
            failed.append('compile --python %s' % version)

    if failed:
        message = 'The %d compile test(s) listed below (out of %d) failed. See error output above for details.\n%s' % (
            len(failed), total, '\n'.join(failed))

        if args.failure_ok:
            display.error(message)
        else:
            raise ApplicationError(message)


def compile_version(args, python_version, include, exclude):
    """
    :type args: CompileConfig
    :type python_version: str
    :type include: tuple[CompletionTarget]
    :param exclude: tuple[CompletionTarget]
    :rtype: TestResult
    """
    command = 'compile'
    test = ''

    # optional list of regex patterns to exclude from tests
    skip_file = 'test/compile/python%s-skip.txt' % python_version

    if os.path.exists(skip_file):
        with open(skip_file, 'r') as skip_fd:
            skip_paths = skip_fd.read().splitlines()
    else:
        skip_paths = []

    # augment file exclusions
    skip_paths += [e.path for e in exclude]

    skip_paths = sorted(skip_paths)

    python = 'python%s' % python_version
    cmd = [python, 'test/compile/compile.py']

    if skip_paths:
        cmd += ['-x', '|'.join(skip_paths)]

    cmd += [target.path if target.path == '.' else './%s' % target.path for target in include]

    try:
        stdout, stderr = run_command(args, cmd, capture=True)
        status = 0
    except SubprocessError as ex:
        stdout = ex.stdout
        stderr = ex.stderr
        status = ex.status

    if stderr:
        raise SubprocessError(cmd=cmd, status=status, stderr=stderr, stdout=stdout)

    if args.explain:
        return TestSkipped(command, test, python_version=python_version)

    pattern = r'^(?P<path>[^:]*):(?P<line>[0-9]+):(?P<column>[0-9]+): (?P<message>.*)$'

    results = [re.search(pattern, line).groupdict() for line in stdout.splitlines()]

    results = [TestMessage(
        message=r['message'],
        path=r['path'].replace('./', ''),
        line=int(r['line']),
        column=int(r['column']),
    ) for r in results]

    if results:
        return TestFailure(command, test, messages=results, python_version=python_version)

    return TestSuccess(command, test, python_version=python_version)


def intercept_command(args, cmd, target_name, capture=False, env=None, data=None, cwd=None, python_version=None):
    """
    :type args: TestConfig
    :type cmd: collections.Iterable[str]
    :type capture: bool
    :type env: dict[str, str] | None
    :type data: str | None
    :type cwd: str | None
    :type python_version: str | None
    :rtype: str | None, str | None
    """
    if not env:
        env = common_environment()

    cmd = list(cmd)
    inject_path = get_coverage_path(args)
    config_path = os.path.join(inject_path, 'injector.json')
    version = python_version or args.python_version
    interpreter = find_executable('python%s' % version)
    coverage_file = os.path.abspath(os.path.join(inject_path, '..', 'output', '%s=%s=%s=%s=coverage' % (
        args.command, target_name, args.coverage_label or 'local-%s' % version, version)))

    env['PATH'] = inject_path + os.pathsep + env['PATH']
    env['ANSIBLE_TEST_PYTHON_VERSION'] = version
    env['ANSIBLE_TEST_PYTHON_INTERPRETER'] = interpreter

    config = dict(
        python_interpreter=interpreter,
        coverage_file=coverage_file if args.coverage else None,
    )

    if not args.explain:
        with open(config_path, 'w') as config_fd:
            json.dump(config, config_fd, indent=4, sort_keys=True)

    return run_command(args, cmd, capture=capture, env=env, data=data, cwd=cwd)


def get_coverage_path(args):
    """
    :type args: TestConfig
    :rtype: str
    """
    global coverage_path  # pylint: disable=locally-disabled, global-statement, invalid-name

    if coverage_path:
        return os.path.join(coverage_path, 'coverage')

    prefix = 'ansible-test-coverage-'
    tmp_dir = '/tmp'

    if args.explain:
        return os.path.join(tmp_dir, '%stmp' % prefix, 'coverage')

    src = os.path.abspath(os.path.join(os.getcwd(), 'test/runner/injector/'))

    coverage_path = tempfile.mkdtemp('', prefix, dir=tmp_dir)
    os.chmod(coverage_path, stat.S_IRWXU | stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH | stat.S_IXOTH)

    shutil.copytree(src, os.path.join(coverage_path, 'coverage'))
    shutil.copy('.coveragerc', os.path.join(coverage_path, 'coverage', '.coveragerc'))

    for root, dir_names, file_names in os.walk(coverage_path):
        for name in dir_names + file_names:
            os.chmod(os.path.join(root, name), stat.S_IRWXU | stat.S_IRGRP | stat.S_IXGRP | stat.S_IROTH | stat.S_IXOTH)

    for directory in 'output', 'logs':
        os.mkdir(os.path.join(coverage_path, directory))
        os.chmod(os.path.join(coverage_path, directory), stat.S_IRWXU | stat.S_IRWXG | stat.S_IRWXO)

    atexit.register(cleanup_coverage_dir)

    return os.path.join(coverage_path, 'coverage')


def cleanup_coverage_dir():
    """Copy over coverage data from temporary directory and purge temporary directory."""
    output_dir = os.path.join(coverage_path, 'output')

    for filename in os.listdir(output_dir):
        src = os.path.join(output_dir, filename)
        dst = os.path.join(os.getcwd(), 'test', 'results', 'coverage')
        shutil.copy(src, dst)

    logs_dir = os.path.join(coverage_path, 'logs')

    for filename in os.listdir(logs_dir):
        random_suffix = ''.join(random.choice(string.ascii_letters + string.digits) for _ in range(8))
        new_name = '%s.%s.log' % (os.path.splitext(os.path.basename(filename))[0], random_suffix)
        src = os.path.join(logs_dir, filename)
        dst = os.path.join(os.getcwd(), 'test', 'results', 'logs', new_name)
        shutil.copy(src, dst)

    shutil.rmtree(coverage_path)


def get_changes_filter(args):
    """
    :type args: TestConfig
    :rtype: list[str]
    """
    paths = detect_changes(args)

    if paths is None:
        return []  # change detection not enabled, do not filter targets

    if not paths:
        raise NoChangesDetected()

    commands = categorize_changes(paths, args.command)

    targets = commands.get(args.command)

    if targets is None:
        raise NoTestsForChanges()

    if targets == ['all']:
        return []  # changes require testing all targets, do not filter targets

    return targets


def detect_changes(args):
    """
    :type args: TestConfig
    :rtype: list[str] | None
    """
    if is_shippable():
        display.info('Shippable detected, collecting parameters from environment.')
        paths = detect_changes_shippable(args)
    elif args.changed_from or args.changed_path:
        paths = args.changed_path or []
        if args.changed_from:
            with open(args.changed_from, 'r') as changes_fd:
                paths += changes_fd.read().splitlines()
    elif args.changed:
        paths = detect_changes_local(args)
    else:
        return None  # change detection not enabled

    display.info('Detected changes in %d file(s).' % len(paths))

    for path in paths:
        display.info(path, verbosity=1)

    return paths


def detect_changes_shippable(args):
    """Initialize change detection on Shippable.
    :type args: TestConfig
    :rtype: list[str]
    """
    git = Git(args)
    result = ShippableChanges(args, git)

    if result.is_pr:
        job_type = 'pull request'
    elif result.is_tag:
        job_type = 'tag'
    else:
        job_type = 'merge commit'

    display.info('Processing %s for branch %s commit %s' % (job_type, result.branch, result.commit))

    if not args.metadata.changes:
        args.metadata.populate_changes(result.diff)

    return result.paths


def detect_changes_local(args):
    """
    :type args: TestConfig
    :rtype: list[str]
    """
    git = Git(args)
    result = LocalChanges(args, git)

    display.info('Detected branch %s forked from %s at commit %s' % (
        result.current_branch, result.fork_branch, result.fork_point))

    if result.untracked and not args.untracked:
        display.warning('Ignored %s untracked file(s). Use --untracked to include them.' %
                        len(result.untracked))

    if result.committed and not args.committed:
        display.warning('Ignored %s committed change(s). Omit --ignore-committed to include them.' %
                        len(result.committed))

    if result.staged and not args.staged:
        display.warning('Ignored %s staged change(s). Omit --ignore-staged to include them.' %
                        len(result.staged))

    if result.unstaged and not args.unstaged:
        display.warning('Ignored %s unstaged change(s). Omit --ignore-unstaged to include them.' %
                        len(result.unstaged))

    names = set()

    if args.tracked:
        names |= set(result.tracked)
    if args.untracked:
        names |= set(result.untracked)
    if args.committed:
        names |= set(result.committed)
    if args.staged:
        names |= set(result.staged)
    if args.unstaged:
        names |= set(result.unstaged)

    if not args.metadata.changes:
        args.metadata.populate_changes(result.diff)

        for path in result.untracked:
            if is_binary_file(path):
                args.metadata.changes[path] = ((0, 0),)
                continue

            with open(path, 'r') as source_fd:
                line_count = len(source_fd.read().splitlines())

            args.metadata.changes[path] = ((1, line_count),)

    return sorted(names)


def get_integration_filter(args, targets):
    """
    :type args: IntegrationConfig
    :type targets: tuple[IntegrationTarget]
    :rtype: list[str]
    """
    if args.tox:
        # tox has the same exclusions as the local environment
        return get_integration_local_filter(args, targets)

    if args.docker:
        return get_integration_docker_filter(args, targets)

    if args.remote:
        return get_integration_remote_filter(args, targets)

    return get_integration_local_filter(args, targets)


def get_integration_local_filter(args, targets):
    """
    :type args: IntegrationConfig
    :type targets: tuple[IntegrationTarget]
    :rtype: list[str]
    """
    exclude = []

    if os.getuid() != 0:
        skip = 'needs/root/'
        skipped = [target.name for target in targets if skip in target.aliases]
        if skipped:
            exclude.append(skip)
            display.warning('Excluding tests marked "%s" which require running as root: %s'
                            % (skip.rstrip('/'), ', '.join(skipped)))

    # consider explicit testing of destructive as though --allow-destructive was given
    include_destructive = any(target.startswith('destructive/') for target in args.include)

    if not args.allow_destructive and not include_destructive:
        skip = 'destructive/'
        skipped = [target.name for target in targets if skip in target.aliases]
        if skipped:
            exclude.append(skip)
            display.warning('Excluding tests marked "%s" which require --allow-destructive to run locally: %s'
                            % (skip.rstrip('/'), ', '.join(skipped)))

    return exclude


def get_integration_docker_filter(args, targets):
    """
    :type args: IntegrationConfig
    :type targets: tuple[IntegrationTarget]
    :rtype: list[str]
    """
    exclude = []

    if not args.docker_privileged:
        skip = 'needs/privileged/'
        skipped = [target.name for target in targets if skip in target.aliases]
        if skipped:
            exclude.append(skip)
            display.warning('Excluding tests marked "%s" which require --docker-privileged to run under docker: %s'
                            % (skip.rstrip('/'), ', '.join(skipped)))

    if args.docker.endswith('py3'):
        skip = 'skip/python3/'
        skipped = [target.name for target in targets if skip in target.aliases]
        if skipped:
            exclude.append(skip)
            display.warning('Excluding tests marked "%s" which are not yet supported on python 3: %s'
                            % (skip.rstrip('/'), ', '.join(skipped)))

    return exclude


def get_integration_remote_filter(args, targets):
    """
    :type args: IntegrationConfig
    :type targets: tuple[IntegrationTarget]
    :rtype: list[str]
    """
    parts = args.remote.split('/', 1)

    platform = parts[0]

    exclude = []

    skip = 'skip/%s/' % platform
    skipped = [target.name for target in targets if skip in target.aliases]
    if skipped:
        exclude.append(skip)
        display.warning('Excluding tests marked "%s" which are not yet supported on %s: %s'
                        % (skip.rstrip('/'), platform, ', '.join(skipped)))

    return exclude


class EnvironmentDescription(object):
    """Description of current running environment."""
    def __init__(self):
        """Initialize snapshot of environment configuration."""
        versions = ['']
        versions += SUPPORTED_PYTHON_VERSIONS
        versions += list(set(v.split('.')[0] for v in SUPPORTED_PYTHON_VERSIONS))

        python_paths = dict((v, find_executable('python%s' % v, required=False)) for v in sorted(versions))
        python_versions = dict((v, self.get_version([python_paths[v], '-V'])) for v in sorted(python_paths) if python_paths[v])

        pip_paths = dict((v, find_executable('pip%s' % v, required=False)) for v in sorted(versions))
        pip_versions = dict((v, self.get_version([pip_paths[v], '--version'])) for v in sorted(pip_paths) if pip_paths[v])
        pip_interpreters = dict((v, self.get_shebang(pip_paths[v])) for v in sorted(pip_paths) if pip_paths[v])

        self.data = dict(
            python_paths=python_paths,
            python_versions=python_versions,
            pip_paths=pip_paths,
            pip_versions=pip_versions,
            pip_interpreters=pip_interpreters,
        )

    def __str__(self):
        """
        :rtype: str
        """
        return json.dumps(self.data, sort_keys=True, indent=4)

    def validate(self, target_name, throw):
        """
        :type target_name: str
        :type throw: bool
        :rtype: bool
        """
        current = EnvironmentDescription()

        original_json = str(self)
        current_json = str(current)

        if original_json == current_json:
            return True

        message = ('Test target "%s" has changed the test environment!\n'
                   'If these changes are necessary, they must be reverted before the test finishes.\n'
                   '>>> Original Environment\n'
                   '%s\n'
                   '>>> Current Environment\n'
                   '%s' % (target_name, original_json, current_json))

        if throw:
            raise ApplicationError(message)

        display.error(message)

        return False

    @staticmethod
    def get_version(command):
        """
        :type command: list[str]
        :rtype: str
        """
        stdout, stderr = raw_command(command, capture=True, cmd_verbosity=2)
        return (stdout or '').strip() + (stderr or '').strip()

    @staticmethod
    def get_shebang(path):
        """
        :type path: str
        :rtype: str
        """
        with open(path) as script_fd:
            return script_fd.readline()


class NoChangesDetected(ApplicationWarning):
    """Exception when change detection was performed, but no changes were found."""
    def __init__(self):
        super(NoChangesDetected, self).__init__('No changes detected.')


class NoTestsForChanges(ApplicationWarning):
    """Exception when changes detected, but no tests trigger as a result."""
    def __init__(self):
        super(NoTestsForChanges, self).__init__('No tests found for detected changes.')


class ShellConfig(EnvironmentConfig):
    """Configuration for the shell command."""
    def __init__(self, args):
        """
        :type args: any
        """
        super(ShellConfig, self).__init__(args, 'shell')


class SanityConfig(TestConfig):
    """Configuration for the sanity command."""
    def __init__(self, args):
        """
        :type args: any
        """
        super(SanityConfig, self).__init__(args, 'sanity')

        self.test = args.test  # type: list [str]
        self.skip_test = args.skip_test  # type: list [str]
        self.list_tests = args.list_tests  # type: bool

        if args.base_branch:
            self.base_branch = args.base_branch  # str
        elif is_shippable():
            try:
                self.base_branch = os.environ['BASE_BRANCH']  # str
            except KeyError as ex:
                raise MissingEnvironmentVariable(name=ex.args[0])

            if self.base_branch:
                self.base_branch = 'origin/%s' % self.base_branch
        else:
            self.base_branch = ''


class IntegrationConfig(TestConfig):
    """Configuration for the integration command."""
    def __init__(self, args, command):
        """
        :type args: any
        :type command: str
        """
        super(IntegrationConfig, self).__init__(args, command)

        self.start_at = args.start_at  # type: str
        self.start_at_task = args.start_at_task  # type: str
        self.allow_destructive = args.allow_destructive if 'allow_destructive' in args else False  # type: bool
        self.retry_on_error = args.retry_on_error  # type: bool


class PosixIntegrationConfig(IntegrationConfig):
    """Configuration for the posix integration command."""

    def __init__(self, args):
        """
        :type args: any
        """
        super(PosixIntegrationConfig, self).__init__(args, 'integration')


class WindowsIntegrationConfig(IntegrationConfig):
    """Configuration for the windows integration command."""

    def __init__(self, args):
        """
        :type args: any
        """
        super(WindowsIntegrationConfig, self).__init__(args, 'windows-integration')

        self.windows = args.windows  # type: list [str]

        if self.windows:
            self.allow_destructive = True


class NetworkIntegrationConfig(IntegrationConfig):
    """Configuration for the network integration command."""

    def __init__(self, args):
        """
        :type args: any
        """
        super(NetworkIntegrationConfig, self).__init__(args, 'network-integration')

        self.platform = args.platform  # type list [str]


class UnitsConfig(TestConfig):
    """Configuration for the units command."""
    def __init__(self, args):
        """
        :type args: any
        """
        super(UnitsConfig, self).__init__(args, 'units')

        self.collect_only = args.collect_only  # type: bool


class CompileConfig(TestConfig):
    """Configuration for the compile command."""
    def __init__(self, args):
        """
        :type args: any
        """
        super(CompileConfig, self).__init__(args, 'compile')


class Delegate(Exception):
    """Trigger command delegation."""
    def __init__(self, exclude=None, require=None):
        """
        :type exclude: list[str] | None
        :type require: list[str] | None
        """
        super(Delegate, self).__init__()

        self.exclude = exclude or []
        self.require = require or []


class AllTargetsSkipped(ApplicationWarning):
    """All targets skipped."""
    def __init__(self):
        super(AllTargetsSkipped, self).__init__('All targets skipped.')