doc(robot): add readme for robot tests.

Refs:CTOR-666

tests/README.md

@@ -0,0 +1,67 @@
+# centreon-plugins Automated tests
+
+## Robot tests
+
+In this project robot is used to order the integration tests.
+
+### install snmpsim
+
+See docker image in ./github/docker/testing/ to find the right package to install and the method to install it.
+Once snmpsim is installed, you need to create the snmp user : 
+
+````bash
+useradd snmp
+mkdir -p /var/lib/snmp/cert_indexes/
+chown snmp:snmp -R /var/lib/snmp/cert_indexes/
+````
+
+to launch snmpsim use this from the root of the project (one level above this file) :
+```bash
+sudo snmpsim-command-responder --logging-method=null --agent-udpv4-endpoint=127.0.0.1:2024 --process-user=snmp --process-group=snmp --data-dir='./tests' &
+# to test it :  snmpwalk -v2c -c hardware/server/lenovo/xcc/snmp/system-health-ok 127.0.0.1:2024
+```
+
+test should be run with the "robot" binary, indicating the path to the test file to run. 
+robot consider every file with .robot extension and try to execute every test case in it. 
+
+```bash
+robot tests/
+```
+
+you can filter the tests run by specifying -e to exclude and -i to include a specific tag before the file path.
+
+
+## Anonymize tests
+
+As most snmpwalk are provided by users, a script allow to anonymize the data and remove oid not used.
+the option  `--no-anonymization` allow to not anonymize the data and only remove oid not used.
+
+```bash
+perl ./tests/scripts/slim_walk.pl --snmpwalk-path=tests/hardware/client.snmpwalk > smaller-file.snmpwalk
+```
+
+
+## unit tests
+
+In this project perl test::v0 is used to run unit tests.
+
+## test coverage
+To check your test coverage you can use Deve::Cover
+when launching any type of test, prepend this to your command : 
+
+```bash
+PERL5OPT=-MDevel::Cover
+```
+
+for exemple for robot : 
+
+```bash
+PERL5OPT=-MDevel::Cover robot tests/
+```
+
+It will create a cover_db/ folder to store all data, you can use the `cover` to generate a html report. 
+```bash
+cover
+```
+
+Then open the coverage.html file in the cover_db/ folder to navigate your code with coverage.