Add test `Draw_segments_no_traj`

Trajectories/Tests/tests.json

@@ -167,5 +167,15 @@
             "component_1980897.gv",
             "-t", "$my_data_dir/Eurec4A/Graph_anti_c19e69d/traj_segm.json"
 	]
+    },
+    "Draw_segments_no_traj":
+    {
+	"description": "draw_segments.py without the option -t.",
+	"command":
+	[
+            "$src_dir/Trajectories/draw_segments.py",
+            "$tests_old_dir/Cost_function_no_debug/segments_cost_functions.graphml",
+            "segments.gv"
+	]
     }
 }