add instructions for how to run the test suite. These instructions are incomplete but a useful starting point

Author: marcuswestin

Readme.md

@@ -858,6 +858,15 @@ will have:
 * As much debugging output and information about your environment (mysql
   version, node version, os, etc.) as you can gather.
 
+## Running unit tests
+
+Set the environment variables `MYSQL_DATABASE`, `MYSQL_HOST`, `MYSQL_PORT`, `MYSQL_USER` and `MYSQL_PASSWORD`. Then run `make test`. E.g.
+
+  mysql -u root -e "CREATE DATABASE IF NOT EXISTS node_mysql_test_db"
+  mysql -u root -e "CREATE USER 'node_mysql_test'@'localhost' IDENTIFIED BY ''"
+  mysql -u root -e "GRANT ALL ON node_mysql_test_db.* TO 'node_mysql_test'@'%'"
+  export MYSQL_DATABASE=node_mysql_test_db && export MYSQL_USER=node_mysql_test && make test
+
 ## Todo
 
 * Prepared statements