Re: [RFC PATCH 5/8] tests_pytest: Implement fetch_asset() method for downloading assets

["Daniel P. Berrangé" <berrange@redhat.com>]

On Thu, Jul 11, 2024 at 01:55:43PM +0200, Thomas Huth wrote:
> In the pytests, we cannot use the fetch_asset() function from Avocado
> anymore, so we have to provide our own implementation now instead.
> Thus add such a function based on the _download_with_cache() function
> from tests/vm/basevm.py for this purpose.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  tests/pytest/qemu_pytest/__init__.py | 40 ++++++++++++++++++++--------
>  1 file changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/tests/pytest/qemu_pytest/__init__.py b/tests/pytest/qemu_pytest/__init__.py
> index e3ed32e3de..73d80b3828 100644
> --- a/tests/pytest/qemu_pytest/__init__.py
> +++ b/tests/pytest/qemu_pytest/__init__.py
> @@ -11,6 +11,7 @@
>  # This work is licensed under the terms of the GNU GPL, version 2 or
>  # later.  See the COPYING file in the top-level directory.
>  
> +import hashlib
>  import logging
>  import os
>  import shutil
> @@ -201,17 +202,34 @@ def setUp(self, bin_prefix):
>          self.assertIsNotNone(SOURCE_DIR,'PYTEST_SOURCE_ROOT must be set')
>          self.assertIsNotNone(self.qemu_bin, 'PYTEST_QEMU_BINARY must be set')
>  
> -    def fetch_asset(self, name,
> -                    asset_hash, algorithm=None,
> -                    locations=None, expire=None,
> -                    find_only=False, cancel_on_missing=True):
> -        return super().fetch_asset(name,
> -                        asset_hash=asset_hash,
> -                        algorithm=algorithm,
> -                        locations=locations,
> -                        expire=expire,
> -                        find_only=find_only,
> -                        cancel_on_missing=cancel_on_missing)
> +    def check_hash(self, file_name, expected_hash):
> +        if not expected_hash:
> +            return True
> +        if len(expected_hash) == 32:
> +            sum_prog = 'md5sum'
> +        elif len(expected_hash) == 40:
> +            sum_prog = 'sha1sum'
> +        elif len(expected_hash) == 64:
> +            sum_prog = 'sha256sum'
> +        elif len(expected_hash) == 128:
> +            sum_prog = 'sha512sum'
> +        else:
> +            raise Exception("unknown hash type")

Why shouldn't we just standardize on sha256 as we convert each test
to pytest ? sha512 is overkill, and md5/sha1 shouldn't really be used
anymore.

> +        checksum = subprocess.check_output([sum_prog, file_name]).split()[0]
> +        return expected_hash == checksum.decode("utf-8")
> +
> +    def fetch_asset(self, url, asset_hash):
> +        cache_dir = os.path.expanduser("~/.cache/qemu/download")
> +        if not os.path.exists(cache_dir):
> +            os.makedirs(cache_dir)
> +        fname = os.path.join(cache_dir,
> +                             hashlib.sha1(url.encode("utf-8")).hexdigest())
> +        if os.path.exists(fname) and self.check_hash(fname, asset_hash):
> +            return fname
> +        logging.debug("Downloading %s to %s...", url, fname)
> +        subprocess.check_call(["wget", "-c", url, "-O", fname + ".download"])
> +        os.rename(fname + ".download", fname)
> +        return fname

To avoid a dep on an external command that may not be installed,
I think we could replace wget with native python code:

 import urllib
 from shutil import copyfileobj
 
 with urllib.request.urlopen(url) as src:
    with open(fname + ".download", "w+") as dst
       copyfileobj(src, dst)


With regards,
Daniel
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