Bug 1451310 - [mozrunner] Catch exceptions when starting the client process. r=ahal

If a ProcessHandler instance has been created, but mozprocess fails
to start the child process, a dangling process_handler instance is
attached to the runner instance. This should be avoided, and a
RunnerNotStartedError has to be thrown.

MozReview-Commit-ID: LgNFVaT9qVs

--HG--
extra : rebase_source : c06aef08d7619ac9d3fe94ad29bdae06f0f79364

testing/mozbase/mozrunner/mozrunner/base/runner.py

@@ -17,6 +17,7 @@ try:
     import mozcrash
 except ImportError:
     mozcrash = None
+from six import reraise
 
 from ..application import DefaultContext
 from ..errors import RunnerNotStartedError
@@ -97,6 +98,8 @@ class BaseRunner(object):
         :param timeout: see process_handler.run()
         :param outputTimeout: see process_handler.run()
         :returns: the process id
+
+        :raises: RunnerNotStartedError
         """
         self.timeout = timeout
         self.output_timeout = outputTimeout
@@ -126,8 +129,14 @@ class BaseRunner(object):
             # TODO: other arguments
         else:
             # this run uses the managed processhandler
-            self.process_handler = self.process_class(cmd, env=encoded_env, **self.process_args)
-            self.process_handler.run(self.timeout, self.output_timeout)
+            try:
+                process = self.process_class(cmd, env=encoded_env, **self.process_args)
+                process.run(self.timeout, self.output_timeout)
+
+                self.process_handler = process
+            except Exception:
+                _, value, tb = sys.exc_info()
+                reraise(RunnerNotStartedError, "Failed to start the process: %s" % value, tb)
 
         self.crashed = 0
         return self.process_handler.pid

testing/mozbase/mozrunner/setup.py

@@ -18,6 +18,7 @@ deps = ['mozdevice >= 0.37',
         'mozlog >= 3.0',
         'mozprocess >= 0.23',
         'mozprofile >= 0.18',
+        'six >= 1.10.0',
         ]
 
 EXTRAS_REQUIRE = {'crash': ['mozcrash >= 1.0']}