slapos.cookbook test: use environment variables to pass eggs directories

slapos.cookbook recipe tests sometimes manipulate buildout eggs working set,
which will install packages from pypi. makeRecipe utilty function was
guessing buildout egg folders by parsing builout.cfg, but since a33844a2
(slapos-testing, slapos-sr-testing: Don't duplicate instance.cfg prologue
that is already provided by stack/nxdtest/instance.cfg, 2021-03-22),
these are defined in an extended profile, so this stopped working.

Instead of this fragile pattern, make the test software release pass the eggs
directories with an explicit environment variable.

slapos/test/utils.py

 """Test helpers
 """
+import os
 import sys
-import os.path
-from zc.buildout.configparser import parse
 
-import logging
 
 def makeRecipe(recipe_class, options, name='test', slap_connection=None):
   """Instanciate a recipe of `recipe_class` with `options` with a buildout
   mapping containing a python and an empty `slapos-connection` mapping, unless
   provided as `slap_connection`.
 
-  If running tests in a buildout folder, the test recipe will reuse the
-  `eggs-directory` and `develop-eggs-directory` from this buildout so that the
+  This function expects the test suite to have set SLAPOS_TEST_EGGS_DIRECTORY
+  and SLAPOS_TEST_DEVELOP_EGGS_DIRECTORY environment variables, so that the
   test recipe does not need to install eggs again when using working set.
-  To prevent test accidentally writing to the buildout's eggs repositories, we
-  set `newest` to false and `offline` to true in this case.
   """
   buildout = {
     'buildout': {
@@ -39,39 +35,12 @@ def makeRecipe(recipe_class, options, name='test', slap_connection=None):
   if slap_connection is not None:
     buildout['slap-connection'] = slap_connection
 
-  # are we in buildout folder ?
-  # in SLAPOS-EGG-TEST the usual layout is
-  # ${buildout:directory}/parts/slapos-repository/slapos/test/utils.py in instance buildout, so try
-  # to find a buildout.cfg relative to this file.
-  # What can also happens is that this repository is used from software folder, this is the case in
-  # SLAPOS-SR-TEST. In this case, ${buildout:eggs} is not set in buildout.cfg and we can only assume
-  # it will be the standards eggs and develop-eggs folders.
+  buildout['buildout']['eggs-directory'] = os.environ['SLAPOS_TEST_EGGS_DIRECTORY']
+  buildout['buildout']['develop-eggs-directory'] = os.environ['SLAPOS_TEST_DEVELOP_EGGS_DIRECTORY']
 
-  # {BASE_DIRECTORY}/parts/slapos-repository/slapos/test/utils.py
-  base_directory = os.path.normpath(os.path.join(os.path.dirname(__file__), '..', '..', '..', '..'))
-  buildout_cfg = os.path.join(base_directory, 'buildout.cfg')
-
-  if os.path.exists(buildout_cfg):
-    with open(buildout_cfg) as f:
-      parsed_cfg = parse(f, buildout_cfg)
-
-    # When buildout_cfg is an instance buildout (like in SLAPOS-EGG-TEST),
-    # there's a ${buildout:eggs-directory} we can use.
-    # When buildout_cfg is a software buildout, we can only guess the
-    # standard eggs directories.
-    eggs_directory = parsed_cfg['buildout'].get(
-      'eggs-directory', os.path.join(base_directory, 'eggs'))
-    develop_eggs_directory = parsed_cfg['buildout'].get(
-      'develop-eggs-directory', os.path.join(base_directory, 'develop-eggs'))
-
-    logging.getLogger(__name__).info(
-        'Using eggs-directory (%s) and develop-eggs-directory (%s) from buildout at %s',
-        eggs_directory,
-        develop_eggs_directory,
-        buildout_cfg)
-    buildout['buildout']['eggs-directory'] = eggs_directory
-    buildout['buildout']['develop-eggs-directory'] = develop_eggs_directory
+  # Prevent test from accidentally writing to the buildout's eggs
   buildout['buildout']['newest'] = False
   buildout['buildout']['offline'] = True
+
   return recipe_class(buildout=buildout, name=name, options=options)
 

software/slapos-testing/buildout.hash.cfg

@@ -15,4 +15,4 @@
 
 [template]
 filename = instance.cfg
-md5sum = a6091981a78cb2b10a97e431adc7615c
+md5sum = 2a82b7d5163d042e85b14a645707a093

software/slapos-testing/instance.cfg

@@ -80,6 +80,8 @@ template = inline:
   export PATH=${coreutils:location}/bin:${curl:location}/bin:${openssl:location}/bin:${git:location}/bin:${libxslt:location}/bin:${socat:location}/bin:${lmsensors:location}/bin:${rsync:location}/bin/:${buildout:bin-directory}:$PATH
   export SLAPOS_TEST_IPV4=$${slap-configuration:ipv4-random}
   export SLAPOS_TEST_IPV6=$${slap-configuration:ipv6-random}
+  export SLAPOS_TEST_EGGS_DIRECTORY=$${buildout:eggs-directory}
+  export SLAPOS_TEST_DEVELOP_EGGS_DIRECTORY=$${buildout:develop-eggs-directory}
 
 
 [slapos-test-runner-dot-nxdtest]