Result: make sure every job has a result directory

This change makes the initialization of the job results happen a lot
earlier than usual, at job instantiation time.  It matches the use
cases of the "Job API", that is, when users want to manipulate job
instances.

With this, change it's possible to execute snippets of code such
as:

   >>> from avocado.core.job import Job
   >>> job = avocado.core.Job()
   >>> job.log.info("Checking if system is ready")

And have that persisted at `job.logdir`, with the "Checking if system
is ready" message logged at `job.logfile`.

This also addresses the issue that, once a job is created, its result
dir is never removed, even if it's empty.  The Avocado test runner
still behaves mostly the same, that is, if the existing job has no
tests (such as when none of the test names given were resolved), it
will proceed to the job execution.  I'd argue that, since it's not
possible (or I'd say desirable) that test resolution happens outside
the context of a job, this is the logical way to go.

This reinforces the change that a job without a test suite is still a
valid job.  That's is the reason for the removal of the test that
checked if job results directory were removed if Avocado was executed
without test names as parameters.

Reference: https://trello.com/c/hu4vxQOLSigned-off-by: NCleber Rosa <crosa@redhat.com>

avocado/core/job.py

@@ -89,7 +89,11 @@ class Job(object):
         if unique_id is None:
             unique_id = job_id.create_unique_job_id()
         self.unique_id = unique_id
+        #: The log directory for this job, also known as the job results
+        #: directory.  If it's set to None, it means that the job results
+        #: directory has not yet been created.
         self.logdir = None
+        self._setup_job_results()
         raw_log_level = settings.get_value('job.output', 'loglevel',
                                            default='debug')
         mapping = {'info': logging.INFO,
@@ -109,6 +113,7 @@ class Job(object):
         self.sysinfo = None
         self.timeout = getattr(self.args, 'job_timeout', 0)
         self.__logging_handlers = {}
+        self.__start_job_logging()
         self.funcatexit = data_structures.CallbackRegister("JobExit %s"
                                                            % self.unique_id,
                                                            _TEST_LOGGER)
@@ -125,6 +130,9 @@ class Job(object):
         self._job_pre_post_dispatcher = None
 
     def _setup_job_results(self):
+        """
+        Prepares a job result directory, also known as logdir, for this job
+        """
         logdir = getattr(self.args, 'logdir', None)
         if self.standalone:
             if logdir is not None:
@@ -140,6 +148,8 @@ class Job(object):
                 logdir = os.path.abspath(logdir)
                 self.logdir = data_dir.create_job_logs_dir(logdir=logdir,
                                                            unique_id=self.unique_id)
+        if not (self.standalone or getattr(self.args, "dry_run", False)):
+            self._update_latest_link()
         self.logfile = os.path.join(self.logdir, "job.log")
         self.idfile = os.path.join(self.logdir, "id")
         with open(self.idfile, 'w') as id_file_obj:
@@ -240,9 +250,6 @@ class Job(object):
                 sysinfo_dir = path.init_dir(self.logdir, 'sysinfo')
                 self.sysinfo = sysinfo.SysInfo(basedir=sysinfo_dir)
 
-    def _remove_job_results(self):
-        shutil.rmtree(self.logdir, ignore_errors=True)
-
     def _make_test_runner(self):
         if hasattr(self.args, 'test_runner'):
             test_runner_class = self.args.test_runner
@@ -291,10 +298,8 @@ class Job(object):
         try:
             suite = loader.loader.discover(urls)
         except loader.LoaderUnhandledUrlError as details:
-            self._remove_job_results()
             raise exceptions.OptionValidationError(details)
         except KeyboardInterrupt:
-            self._remove_job_results()
             raise exceptions.JobError('Command interrupted by user...')
 
         if not getattr(self.args, "dry_run", False):
@@ -421,14 +426,10 @@ class Job(object):
                 :class:`avocado.core.exceptions.JobBaseException` errors,
                 that configure a job failure.
         """
-        self._setup_job_results()
-        self.__start_job_logging()
-
         self.create_test_suite()
         self.pre_tests()
 
         if not self.test_suite:
-            self._remove_job_results()
             if self.urls:
                 e_msg = ("No tests found for given urls, try 'avocado list -V "
                          "%s' for details" % " ".join(self.urls))
@@ -450,8 +451,6 @@ class Job(object):
         self.args.test_result_total = mux.get_number_of_tests(self.test_suite)
 
         self._make_old_style_test_result()
-        if not (self.standalone or getattr(self.args, "dry_run", False)):
-            self._update_latest_link()
         self._make_test_runner()
         self._start_sysinfo()
 
@@ -495,7 +494,6 @@ class Job(object):
                 self.test_suite = self._make_test_suite(self.urls)
             except loader.LoaderError as details:
                 stacktrace.log_exc_info(sys.exc_info(), 'avocado.app.debug')
-                self._remove_job_results()
                 raise exceptions.OptionValidationError(details)
 
     def pre_tests(self):

selftests/functional/test_argument_parsing.py

@@ -72,9 +72,5 @@ class ArgumentParsingErrorEarlyTest(unittest.TestCase):
         self.run_but_fail_before_create_job_dir('--whacky-option passtest',
                                                 exit_codes.AVOCADO_FAIL)
 
-    def test_empty_option(self):
-        self.run_but_fail_before_create_job_dir('',
-                                                exit_codes.AVOCADO_JOB_FAIL)
-
 if __name__ == '__main__':
     unittest.main()