Source code for spack.test.util.file_cache

# Copyright 2013-2022 Lawrence Livermore National Security, LLC and other
# Spack Project Developers. See the top-level COPYRIGHT file for details.
#
# SPDX-License-Identifier: (Apache-2.0 OR MIT)

"""Test Spack's FileCache."""
import os
import sys

import pytest

import llnl.util.filesystem as fs

from spack.util.file_cache import CacheError, FileCache


@pytest.fixture()
def file_cache(tmpdir):
    """Returns a properly initialized FileCache instance"""
    return FileCache(str(tmpdir))


def test_write_and_read_cache_file(file_cache):
    """Test writing then reading a cached file."""
    with file_cache.write_transaction('test.yaml') as (old, new):
        assert old is None
        assert new is not None
        new.write("foobar\n")

    with file_cache.read_transaction('test.yaml') as stream:
        text = stream.read()
        assert text == "foobar\n"


def test_write_and_remove_cache_file(file_cache):
    """Test two write transactions on a cached file. Then try to remove an
    entry from it.
    """

    with file_cache.write_transaction('test.yaml') as (old, new):
        assert old is None
        assert new is not None
        new.write("foobar\n")

    with file_cache.write_transaction('test.yaml') as (old, new):
        assert old is not None
        text = old.read()
        assert text == "foobar\n"
        assert new is not None
        new.write("barbaz\n")

    with file_cache.read_transaction('test.yaml') as stream:
        text = stream.read()
        assert text == "barbaz\n"

    file_cache.remove('test.yaml')

    # After removal the file should not exist
    assert not os.path.exists(file_cache.cache_path('test.yaml'))

    # Whether the lock file exists is more of an implementation detail, on Linux they
    # continue to exist, on Windows they don't.
    # assert os.path.exists(file_cache._lock_path('test.yaml'))


@pytest.mark.skipif(sys.platform == 'win32',
                    reason="Not supported on Windows (yet)")
def test_cache_init_entry_fails(file_cache):
    """Test init_entry failures."""
    relpath = fs.join_path('test-dir', 'read-only-file.txt')
    cachefile = file_cache.cache_path(relpath)
    fs.touchp(cachefile)

    # Ensure directory causes exception
    with pytest.raises(CacheError, match='not a file'):
        file_cache.init_entry(os.path.dirname(relpath))

    # Ensure non-readable file causes exception
    os.chmod(cachefile, 0o200)
    with pytest.raises(CacheError, match='Cannot access cache file'):
        file_cache.init_entry(relpath)

    # Ensure read-only parent causes exception
    relpath = fs.join_path('test-dir', 'another-file.txxt')
    cachefile = file_cache.cache_path(relpath)
    os.chmod(os.path.dirname(cachefile), 0o400)
    with pytest.raises(CacheError, match='Cannot access cache dir'):
        file_cache.init_entry(relpath)


def test_cache_write_readonly_cache_fails(file_cache):
    """Test writing a read-only cached file."""
    filename = 'read-only-file.txt'
    path = file_cache.cache_path(filename)
    fs.touch(path)
    os.chmod(path, 0o400)

    with pytest.raises(CacheError, match='Insufficient permissions to write'):
        file_cache.write_transaction(filename)


@pytest.mark.regression('31475')
def test_delete_is_idempotent(file_cache):
    """Deleting a non-existent key should be idempotent, to simplify life when
    running delete with multiple processes"""
    file_cache.remove('test.yaml')