[lttng-dev] [PATCH lttng-tools] Fix: test: handle env variables undefined

[Jonathan Rajotte]

Prevent errors on non-existent key fetching e.g LD_PRELOAD & LD_LIBRARY_PATH.
Uses .get() with a default empty string to prevent this case.

Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien at efficios.com>
---
 tests/regression/ust/ust-dl/test_ust-dl.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/regression/ust/ust-dl/test_ust-dl.py b/tests/regression/ust/ust-dl/test_ust-dl.py
index 7117ca1..9801012 100644
--- a/tests/regression/ust/ust-dl/test_ust-dl.py
+++ b/tests/regression/ust/ust-dl/test_ust-dl.py
@@ -46,8 +46,8 @@ enable_ust_tracepoint_event(session_info, "*")
 start_session(session_info)
 
 test_env = os.environ.copy()
-test_env["LD_PRELOAD"] += ":liblttng-ust-dl.so"
-test_env["LD_LIBRARY_PATH"] += ":" + test_path
+test_env["LD_PRELOAD"] = test_env.get("LD_PRELOAD", "") + ":liblttng-ust-dl.so"
+test_env["LD_LIBRARY_PATH"] = test_env.get("LD_LIBRARY_PATH", "") + ":" + test_path
 test_process = subprocess.Popen(test_path + "prog",
                                 stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                                 env=test_env)
-- 
2.5.0