test: add an example to illustrate the use of lurette coverage

to check is the worst-case has been reached

test/dijkstra-ring/Makefile

-# Time-stamp: <modified the 11/05/2021 (at 16:46) by Erwan Jahier>
+# Time-stamp: <modified the 28/07/2021 (at 11:44) by Erwan Jahier>
 
 
 test: ring.cmxs lurette1 rdbg_test
@@ -52,4 +52,4 @@ lurette1: ring.lut ring_oracle.lus
 -include Makefile.untracked
 
 clean: genclean
-	rm -f ring_oracle.lus ring.ml
+	rm -f ring.ml

test/dijkstra-ring/ring_oracle.lus

+-- Automatically generated by /home/jahier/.opam/4.12.0/bin/sasa version "v4.5.2" ("6122a58")
+-- on crevetete the 28/7/2021 at 11:23:11
+--sasa -glos ring.dot
+
+include "dijkstra_ring_oracle.lus"
+const an=1; -- actions number
+const pn=8; -- processes number
+const degree=2;
+const min_degree=2;
+const mean_degree=2.000000;
+const diameter=7;
+const card=8;
+const links_number=8;
+const is_cyclic=true;
+const is_connected=true;
+const is_a_tree=false;
+const f=false;
+const t=true;
+const adjacency=[
+	[f,t,f,f,f,f,f,f],
+	[f,f,t,f,f,f,f,f],
+	[f,f,f,t,f,f,f,f],
+	[f,f,f,f,t,f,f,f],
+	[f,f,f,f,f,t,f,f],
+	[f,f,f,f,f,f,t,f],
+	[f,f,f,f,f,f,f,t],
+	[t,f,f,f,f,f,f,f]];
+const k=3;
+
+node oracle(legitimate:bool; 
+  root_c:int;p2_c:int;p3_c:int;p4_c:int;p5_c:int;p6_c:int;p7_c:int;p8_c:int;
+  Enab_root_T,Enab_p2_T,Enab_p3_T,Enab_p4_T,Enab_p5_T,Enab_p6_T,Enab_p7_T,Enab_p8_T:bool;
+  root_T,p2_T,p3_T,p4_T,p5_T,p6_T,p7_T,p8_T:bool) 
+returns (ok, WCReached:bool);
+var
+  	Acti:bool^an^pn;
+	Enab:bool^an^pn;
+let
+  	Acti = [[root_T],[p2_T],[p3_T],[p4_T],[p5_T],[p6_T],[p7_T],[p8_T]];
+  	Enab = [[Enab_root_T],[Enab_p2_T],[Enab_p3_T],[Enab_p4_T],[Enab_p5_T],[Enab_p6_T],[Enab_p7_T],[Enab_p8_T]];
+
+  ok, WCReached = dijkstra_ring_oracle_cov(legitimate, Enab, Acti);
+tel