validate:tools: Enhance the way we detect if ges-launch can be used

We make sure it has been compiled against gst-validate

validate/tools/launcher/apps/ges-launch.py

@@ -19,6 +19,7 @@
 
 import os
 import urlparse
+import subprocess
 from urllib import unquote
 from gi.repository import GES, Gst, GLib
 from baseclasses import GstValidateTest, TestsManager
@@ -166,10 +167,16 @@ class GESTestsManager(TestsManager):
 
 
     def init(self):
-        if which(DEFAULT_GES_LAUNCH):
+        try:
+            if "--set-scenario=" in subprocess.check_output([DEFAULT_GES_LAUNCH, "--help"]):
                 return True
-
-        return False
+            else:
+                self.warning("Can not use ges-launch, it seems not to be compiled against"
+                             " gst-validate")
+        except subprocess.CalledProcessError as e:
+            self.warning("Can not use ges-launch: %s" % e)
+        except OSError as e:
+            self.warning("Can not use ges-launch: %s" % e)
 
     def add_options(self, group):
         group.add_option("-P", "--projects-paths", dest="projects_paths",

validate/tools/launcher/baseclasses.py

@@ -222,13 +222,16 @@ class GstValidateTest(Test):
                                 ))
 
 
-class TestsManager(object):
+class TestsManager(Loggable):
 
     """ A class responsible for managing tests. """
 
     name = ""
 
     def __init__(self):
+
+        Loggable.__init__(self)
+
         self.tests = []
         self.options = None
         self.args = None