Add unit test to clean_caches()

client/cipd.py

 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 """Fetches CIPD client and installs packages."""
 
 import contextlib
 import hashlib
 import json
 import logging
@@ skipping 391 matching lines @@
   # Resolve version to instance id.
   # Is it an instance id already? They look like HEX SHA1.
   if isolated_format.is_valid_hash(version, hashlib.sha1):
     instance_id = version
   elif ':' in version: # it's an immutable tag
     # version_cache is {version_digest -> instance id} mapping.
     # It does not take a lot of disk space.
     version_cache = isolateserver.DiskCache(
         unicode(os.path.join(cache_dir, 'versions')),
         isolateserver.CachePolicies(0, 0, 300),
-        hashlib.sha1)
+        hashlib.sha1,
+        trim=True)
     with version_cache:
       version_cache.cleanup()
       # Convert |version| to a string that may be used as a filename in disk
       # cache by hashing it.
       version_digest = hashlib.sha1(version).hexdigest()
       try:
         with version_cache.getfileobj(version_digest) as f:
           instance_id = f.read()
       except isolateserver.CacheMiss:
         instance_id = resolve_version(
             service_url, package_name, version, timeout=timeoutfn())
         version_cache.write(version_digest, instance_id)
   else: # it's a ref
     instance_id = resolve_version(
         service_url, package_name, version, timeout=timeoutfn())
 
   # instance_cache is {instance_id -> client binary} mapping.
   # It is bounded by 5 client versions.
   instance_cache = isolateserver.DiskCache(
       unicode(os.path.join(cache_dir, 'clients')),
       isolateserver.CachePolicies(0, 0, 5),
-      hashlib.sha1)
+      hashlib.sha1,
+      trim=True)
   with instance_cache:
     instance_cache.cleanup()
     if instance_id not in instance_cache:
       logging.info('Fetching CIPD client %s:%s', package_name, instance_id)
       fetch_url = get_client_fetch_url(
           service_url, package_name, instance_id, timeout=timeoutfn())
       _fetch_cipd_client(instance_cache, instance_id, fetch_url, timeoutfn)
 
     # A single host can run multiple swarming bots, but ATM they do not share
     # same root bot directory. Thus, it is safe to use the same name for the
@@ skipping 27 matching lines @@
   """
   result = []
   for pkg in packages:
     path, name, version = pkg.split(':', 2)
     if not name:
       raise Error('Invalid package "%s": package name is not specified' % pkg)
     if not version:
       raise Error('Invalid package "%s": version is not specified' % pkg)
     result.append((path, name, version))
   return result