added test_user_script_crash test (Epistimio#709)

Detects if a by-design crashing black-box script Traceback is visible in the stderr output of orion.

tests/functional/commands/black_box_fail.py

@@ -0,0 +1,31 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+"""User script that exits with code given in argument."""
+import argparse
+import sys
+from xmlrpc.client import boolean
+
+
+def execute():
+    """Execute a simple pipeline as an example."""
+    # 1. Get the wanted exit code
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--exitcode", "-e", type=int, default=0, help="wanted exit code"
+    )
+    parser.add_argument(
+        "--crash", "-c", action="store_true", help="make a crash happen"
+    )
+    parser.add_argument("-x", type=float, required=True)
+    inputs = parser.parse_args()
+
+    # 2. if needed, crash !
+    if inputs.crash:
+        print("%b" % False)  # black_box_fail.py : this line should crash
+
+    # 3. exit with the wanted code
+    sys.exit(inputs.exitcode)
+
+
+if __name__ == "__main__":
+    execute()

tests/functional/commands/test_hunt_command.py

@@ -35,3 +35,26 @@ def test_no_name(capsys):
     captured = capsys.readouterr().err
 
     assert captured == "Error: No name provided for the experiment.\n"
+
+
+def test_user_script_crash(capfd):
+    """Checks that the Traceback of a crashing user script is output to stderr"""
+
+    orion.core.cli.main(
+        [
+            "--debug",
+            "hunt",
+            "-n",
+            "test",
+            "--exp-max-trials",
+            "1",
+            "./black_box_fail.py",
+            "-c",
+            "-x~uniform(-5,5)",
+        ]
+    )
+
+    out, err = capfd.readouterr()
+
+    assert "Traceback" in err
+    assert "# black_box_fail.py : this line should crash" in err