[pitivi] check: Error messages of GstPluginDependency checks changed to more specific.

[Alexandru Băluț <alexbalut src gnome org>]

commit bd540b9ab251b97a9e7bfd80aba0926aa3c0bdbe
Author: ymdatta <ymdatta protonmail com>
Date:   Wed Dec 12 23:47:54 2018 +0530

    check: Error messages of GstPluginDependency checks changed to more specific.
    
    Fixes #2190

 pitivi/check.py | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)
---
diff --git a/pitivi/check.py b/pitivi/check.py
index 9ca390b3..9765e480 100644
--- a/pitivi/check.py
+++ b/pitivi/check.py
@@ -176,6 +176,23 @@ class GstPluginDependency(Dependency):
     def _format_version(self, plugin):
         return _string_to_list(plugin.get_version())
 
+    def __repr__(self):
+        if self.satisfied:
+            return ""
+
+        if not self.component:
+            # Translators: %s is a Python module name or another os component
+            message = _("- %s GStreamer plug-in not found on the system") % self.modulename
+        else:
+            # Translators: %s is a Python module name or another os component
+            message = _("- %s Gstreamer plug-in version %s is installed but Pitivi requires at least version 
%s") % (
+                self.modulename, self.version_installed, self.version_required_string)
+
+        if self.additional_message is not None:
+            message += "\n    -> " + self.additional_message
+
+        return message
+
 
 class GstDependency(GIDependency):