Bug 917550 - [mozprocess] ProcessHandler commandline attr broken;r=wlach

Consistently store `cmd` as a string and `args` as a list. Throw an
error when `args` are over-specified. Document the complete usage of the
`cmd` and `args` options.

mozprocess/mozprocess/processhandler.py

@@ -31,8 +31,8 @@ class ProcessHandlerMixin(object):
     """
     A class for launching and manipulating local processes.
 
-    :param cmd: command to run.
-    :param args: is a list of arguments to pass to the command (defaults to None).
+    :param cmd: command to run. May be a string or a list. If specified as a list, the first element will be interpreted as the command, and all additional elements will be interpreted as arguments to that command.
+    :param args: list of arguments to pass to the command (defaults to None). Must not be set when `cmd` is specified as a list.
     :param cwd: working directory for command (defaults to None).
     :param env: is the environment to use for the process (defaults to os.environ).
     :param ignore_children: causes system to ignore child processes when True, defaults to False (which tracks child processes).
@@ -582,11 +582,12 @@ def __init__(self,
 
         # It is common for people to pass in the entire array with the cmd and
         # the args together since this is how Popen uses it.  Allow for that.
-        if not isinstance(self.cmd, list):
-            self.cmd = [self.cmd]
-
-        if self.args:
-            self.cmd = self.cmd + self.args
+        if isinstance(self.cmd, list):
+            if self.args != None:
+                raise TypeError("cmd and args must not both be lists")
+            (self.cmd, self.args) = (self.cmd[0], self.cmd[1:])
+        elif self.args is None:
+            self.args = []
 
     @property
     def timedOut(self):
@@ -624,7 +625,7 @@ def run(self, timeout=None, outputTimeout=None):
         args.update(self.keywordargs)
 
         # launch the process
-        self.proc = self.Process(self.cmd, **args)
+        self.proc = self.Process([self.cmd] + self.args, **args)
 
         self.processOutput(timeout=timeout, outputTimeout=outputTimeout)
 

mozprocess/tests/test_mozprocess.py

@@ -136,6 +136,48 @@ def test_process_normal_finish(self):
                               p.proc.returncode,
                               p.didTimeout)
 
+    def test_commandline_no_args(self):
+        """Command line is reported correctly when no arguments are specified"""
+        p = processhandler.ProcessHandler(self.proclaunch, cwd=here)
+        self.assertEqual(p.commandline, self.proclaunch)
+
+    def test_commandline_overspecified(self):
+        """Command line raises an exception when the arguments are specified ambiguously"""
+        err = None
+        try:
+            p = processhandler.ProcessHandler([self.proclaunch, "process_normal_finish.ini"],
+                                              args=["1", "2", "3"],
+                                              cwd=here)
+        except TypeError, e:
+            err = e
+
+        self.assertTrue(err)
+
+    def test_commandline_from_list(self):
+        """Command line is reported correctly when command and arguments are specified in a list"""
+        p = processhandler.ProcessHandler([self.proclaunch, "process_normal_finish.ini"],
+                                          cwd=here)
+        self.assertEqual(p.commandline, self.proclaunch + ' process_normal_finish.ini')
+
+    def test_commandline_over_specified(self):
+        """Command line raises an exception when the arguments are specified ambiguously"""
+        err = None
+        try:
+            p = processhandler.ProcessHandler([self.proclaunch, "process_normal_finish.ini"],
+                                              args=["1", "2", "3"],
+                                              cwd=here)
+        except TypeError, e:
+            err = e
+
+        self.assertTrue(err)
+
+    def test_commandline_from_args(self):
+        """Command line is reported correctly when arguments are specified in a dedicated list"""
+        p = processhandler.ProcessHandler(self.proclaunch,
+                                          args=["1", "2", "3"],
+                                          cwd=here)
+        self.assertEqual(p.commandline, self.proclaunch + ' 1 2 3')
+
     def test_process_wait(self):
         """Process is started runs to completion while we wait indefinitely"""