Ajust test_job_listing.py to validate file_metadata as a JSON object:

 - After commit 646c8d11 the Job parameter file_metadata is enforced to be a JSON object. Tests have to be changed accordingly.

src/fts3rest/fts3rest/tests/functional/test_job_listing.py

@@ -520,21 +520,23 @@ class TestJobListing(TestController):
         self.push_delegation()
 
         job1 = self._submit(file_metadata='a')
-        job2 = self._submit(file_metadata='5')
+        job2 = self._submit(file_metadata={'key': 'value'})
         job3 = self._submit(file_metadata='?')
+        job4 = self._submit(file_metadata={'key': 5})
 
         jobs = self.app.get(
-            url="/jobs/%s?files=job_id,file_metadata" % ','.join([job1, job2, job3]),
+            url="/jobs/%s?files=job_id,file_metadata" % ','.join([job1, job2, job3, job4]),
             status=200).json
 
-        self.assertEqual(3, len(jobs))
+        self.assertEqual(4, len(jobs))
         self.assertEqual(jobs[0]['job_id'], jobs[0]['files'][0]['job_id'])
-        self.assertEqual('a',               jobs[0]['files'][0]['file_metadata'])
+        self.assertEqual({'label': 'a'},               jobs[0]['files'][0]['file_metadata'])
         self.assertEqual(jobs[1]['job_id'], jobs[1]['files'][0]['job_id'])
-        self.assertEqual('5',               jobs[1]['files'][0]['file_metadata'])
+        self.assertEqual({"key": "value"},               jobs[1]['files'][0]['file_metadata'])
         self.assertEqual(jobs[2]['job_id'], jobs[2]['files'][0]['job_id'])
-        self.assertEqual('?',               jobs[2]['files'][0]['file_metadata'])
-
+        self.assertEqual({'label': '?'},               jobs[2]['files'][0]['file_metadata'])
+        self.assertEqual(jobs[3]['job_id'], jobs[3]['files'][0]['job_id'])
+        self.assertEqual({'key': 5},               jobs[3]['files'][0]['file_metadata'])
     def test_query_something_running(self):
         """
         Query if there are any active or submitted files for a given destination surl