Unit testing the Controllers

As you develop the action methods in a Controller, it is highly recommended that you write the unit test for this code. To run the whole test suite:

> grails test-app

To run all tests for a single controller:

>grails test-app MyController

You can even run a single test

>grails test-app MyController testValidData

The results can be seen here:
./test/reports/html/all-tests.html

Awesome Groovy Collections!

There is a short cut for:

if (errorMap?.size() > 0) {
// do something
}

to

if (errorMap) {
// do something
}

same thing in JSP, you can use:

sublist

   def devices
   int start
   int end  
   def subdevices = devices[start..end]