tests: extract testutils.override_os_uname

Combine the very similar override_uname_arch() and override_uname_os()
in a new helper function, to reduce duplication.

Also use a 'try/finally' block to ensure that the original
os.uname() is restored.

This will make it simpler to adopt platform.uname() instead in later
work.

2 files changed, 52 insertions, 0 deletions

diff --git a/tests/testutils/__init__.py b/tests/testutils/__init__.py
index 67378c959..31912fed9 100644
--- a/tests/testutils/__init__.py
+++ b/tests/testutils/__init__.py
@@ -30,3 +30,4 @@ from .junction import generate_junction
 from .runner_integration import wait_for_cache_granularity
 from .python_repo import setup_pypi_repo
 from .yaml import yaml_file_get_provenance
+from .platform import override_os_uname
diff --git a/tests/testutils/platform.py b/tests/testutils/platform.py
new file mode 100644
index 000000000..e00a131bd
--- /dev/null
+++ b/tests/testutils/platform.py
@@ -0,0 +1,51 @@
+#
+#  Copyright (C) 2019 Bloomberg Finance LP
+#
+#  This program is free software; you can redistribute it and/or
+#  modify it under the terms of the GNU Lesser General Public
+#  License as published by the Free Software Foundation; either
+#  version 2 of the License, or (at your option) any later version.
+#
+#  This library is distributed in the hope that it will be useful,
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	 See the GNU
+#  Lesser General Public License for more details.
+#
+#  You should have received a copy of the GNU Lesser General Public
+#  License along with this library. If not, see <http://www.gnu.org/licenses/>.
+#
+#  Authors:
+#        Angelos Evripiotis <jevripiotis@bloomberg.net>
+
+from contextlib import contextmanager
+import os
+
+
+# override_platform_uname()
+#
+# Context manager to override the reported value of `os.uname()`.
+#
+# Args:
+#   system (str): Optional str to replace the 1st entry of uname with.
+#   machine (str): Optional str to replace the 5th entry of uname with.
+#
+@contextmanager
+def override_os_uname(*, system=None, machine=None):
+    orig_func = os.uname
+    result = orig_func()
+
+    result = list(result)
+    if system is not None:
+        result[0] = system
+    if machine is not None:
+        result[4] = machine
+    result = tuple(result)
+
+    def override_func():
+        return result
+
+    os.uname = override_func
+    try:
+        yield
+    finally:
+        os.uname = orig_func