[test-suite] Use shellcommand.wrap() when adding the run_under command

[sbaranga]

Summary

When mutating a command like "cd X; ./cmd" to add the run_under
arguments (for example "taskset -c 1"), the mutated command needs to
maintain the "cd X;" part in the output command prefix:

"cd X; taskset -c 1 ./cmd"

If we don't do this, the mutated command cannot be parsed.

Use shellcommand.wrap() to mutate the command instead of string
concatenation, since shellcommand knows how to handle the
"cd X; ..".

[MatzeB]

LGTM. Though I would recommend adding some checks:

litsupport/run_under.py

9–10

This looks like it can fit into a single line.

You should play it safe and abort if run_under_cmd has any of the stdin, stdout, stderr, workdir, envvars properties set because they will get lost here.

[sbaranga]

Raise an exception when the run_under command has any of the stdin, stdout, stderr, workdir or envvars set.

[sbaranga]

Thanks for the review! I've made the changes and committed in r271661.

litsupport/run_under.py

 from litsupport import shellcommand
 from litsupport import testplan
 
 
 def mutateCommandLine(context, commandline):
-    return context.config.run_under + " " + commandline
+    cmd = shellcommand.parse(commandline)
+    run_under_cmd = shellcommand.parse(context.config.run_under)
+
+    if (run_under_cmd.stdin is not None or
+        run_under_cmd.stdout is not None or
+        run_under_cmd.stderr is not None or
+        run_under_cmd.workdir is not None or
+        run_under_cmd.envvars):
+        raise Exception("invalid run_under argument!")
+
+    cmd.wrap(run_under_cmd.executable, run_under_cmd.arguments)
+
+    return cmd.toCommandline()
 
 
 def mutatePlan(context, plan):
     run_under = context.config.run_under
     if run_under:
         plan.runscript = testplan.mutateScript(context, plan.runscript,
                                                mutateCommandLine)