overlap_index; add a should-get test

link to #3830
3 jobs for feature-s/3830-calculer-l-index-de-morisita in 5 minutes and 50 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test Tools
passed #303517
test_tools

00:00:06

 
  Test Unit
passed #303518
web
test_server_unit

00:00:16

 
  Test Functional
passed #303519
docker x86_64
test_server_functional

00:05:26