avocado.core.remote: Handle urls without assigned files

The remote runner url=>file is rather simple, it takes the url and if
the file does not exists, it uses test_dir + url. Fabric should copy
that file, but it silently ignores missing files, therefor (unless the
file already exists on the remote machine) it fails later in the code
with "Unable to discover ...".

This patch adds check to make sure the mapped file exists. If not it
raises exception.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

avocado/core/remote/runner.py

@@ -61,6 +61,9 @@ class RemoteTestRunner(TestRunner):
             url = self.job.urls[i]
             if not os.path.exists(url):     # use test_dir path + py
                 url = os.path.join(data_dir.get_test_dir(), url)
+            if not os.path.exists(url):
+                raise exceptions.JobError("Unable to map test id '%s' to file"
+                                          % self.job.urls[i])
             url = os.path.abspath(url)  # always use abspath; avoid clashes
             # modify url to remote_path + abspath
             paths.add(url)