The build/tests/functional subdirectories are consuming huge amounts
of disk space.

Split the location for scratch files into a 'scratch' sub-directory,
separate from log files, and delete it upon completion of each test.
The new env variable QEMU_TEST_KEEP_SCRATCH can be set to preserve
this scratch dir for debugging access if required.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 docs/devel/testing/functional.rst      |  6 ++++++
 tests/functional/qemu_test/testcase.py | 14 +++++++++-----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/docs/devel/testing/functional.rst b/docs/devel/testing/functional.rst
index bf6f1bb81e..6b5d0c5b98 100644
--- a/docs/devel/testing/functional.rst
+++ b/docs/devel/testing/functional.rst
@@ -65,6 +65,12 @@ to the QEMU binary that should be used for the test, for example::
   $ export QEMU_TEST_QEMU_BINARY=$PWD/qemu-system-x86_64
   $ python3 ../tests/functional/test_file.py
 
+The test framework will automatically purge any scratch files created during
+the tests. If needing to debug a failed test, it is possible to keep these
+files around on disk by setting ```QEMU_TEST_KEEP_SCRATCH=1``` as an env
+variable.  Any preserved files will be deleted the next time the test is run
+without this variable set.
+
 Overview
 --------
 
diff --git a/tests/functional/qemu_test/testcase.py b/tests/functional/qemu_test/testcase.py
index 411978b5ef..b9418e2ac0 100644
--- a/tests/functional/qemu_test/testcase.py
+++ b/tests/functional/qemu_test/testcase.py
@@ -13,8 +13,9 @@
 
 import logging
 import os
-import subprocess
 import pycotap
+import shutil
+import subprocess
 import sys
 import unittest
 import uuid
@@ -40,11 +41,12 @@ def setUp(self, bin_prefix):
         self.assertIsNotNone(self.qemu_bin, 'QEMU_TEST_QEMU_BINARY must be set')
         self.arch = self.qemu_bin.split('-')[-1]
 
-        self.workdir = os.path.join(BUILD_DIR, 'tests/functional', self.arch,
-                                    self.id())
+        self.outputdir = os.path.join(BUILD_DIR, 'tests', 'functional',
+                                      self.arch, self.id())
+        self.workdir = os.path.join(self.outputdir, 'scratch')
         os.makedirs(self.workdir, exist_ok=True)
 
-        self.logdir = self.workdir
+        self.logdir = self.outputdir
         self.log_filename = os.path.join(self.logdir, 'base.log')
         self.log = logging.getLogger('qemu-test')
         self.log.setLevel(logging.DEBUG)
@@ -56,6 +58,8 @@ def setUp(self, bin_prefix):
         self.log.addHandler(self._log_fh)
 
     def tearDown(self):
+        if "QEMU_TEST_KEEP_SCRATCH" not in os.environ:
+            shutil.rmtree(self.workdir)
         self.log.removeHandler(self._log_fh)
 
     def main():
@@ -108,7 +112,7 @@ def setUp(self):
 
         console_log = logging.getLogger('console')
         console_log.setLevel(logging.DEBUG)
-        self.console_log_name = os.path.join(self.workdir, 'console.log')
+        self.console_log_name = os.path.join(self.logdir, 'console.log')
         self._console_log_fh = logging.FileHandler(self.console_log_name,
                                                    mode='w')
         self._console_log_fh.setLevel(logging.DEBUG)
-- 
2.46.0