5 Handy Groovy Shortcuts

Groovy's main advantage over Java programming is the ability for a developer to implement a solution in fewer lines of code. Groovy's idioms produce concise, short, and clean code. Of course, on first look the code may look strange to a Java developer. But once you learn Groovy's shortcuts you realize the value of consciseness and how less noise produces easier maintenance of code. To me, this is simple: "Since there is less code to look at, there is less code to understand. Learn the shortcuts and idioms and produce less code to do more."

Over the last year, I adopted Groovy as an enterprise implementation language. Here are 5 Groovy programming shortcuts that I found to be very handy. They are listed as tests, in the model of TDD.

Spread Dot Operator

The spread dot operator calls a method on every item in a collection. Upon the invocations, it creates a new list from the return items.  So instead of looping through a collection to make a call on each object, use the spread dot operator.

Let's say we want to get the first 3 letters of each username:

    void testSpreadDot() {
      def emails = ["nirav@yahoo.com", "bob@gmail.com", "jacob@msn.com"]
      def firstThreeLetters = emails*.getAt(0..2)
      assertEquals(firstThreeLetters, ["nir", "bob", "jac"])
    } 

This is very useful when utilizing several common design patterns or just plan old polymorphism. You are able to call an interface many times with minimal code.

mockFor and MockFor in Grails

I recently came across a small shortcoming in Grails' mockFor feature. I wasn't able to return a value from a service that was mocked. I get an error where the return value is always a closure, not the value I intended. (Note this occurred in grails v1.1).

I found that using Groovy's MockFor is just as convenient and does not contain this shortcoming.

Concept Overview

Often a developer would like to use mocks to isolate code and verify that a unit of code is operating correctly. The rationale is: "Given that collaborators are behaving in a specific way, the code under test behaves as expected." In other words, if collaborator returns A, then the code under test will perform B. If the collaborator returns C, then the code under test will perform D.

Many Java mock frameworks provide this ability, including EasyMock and JMock, to name a few.

mockFor Shortcoming

On a grails project, I wanted a mock to return a certain value. This did not work. Let me provide an example to illustrate the problem.

Grails SpringOne 2GX Presentation Summary

This month I had the privilege of attending the SpringOne 2GX conference in Chicago. It was an amazing event for me where I got to meet the leaders in the field and learned many new things.  I primarily went to dive in deep into the latest Groovy and Grails developments, technologies, and trends. This blog serves as a housing place for my notes on each presentation I attended.  At the end of the blog, I have posted the original presentations and made them available.


Grails 1.3 Update
by Graeme Rocher

Industry Usage

• Grails has 499 plugins
• Lots of high profile sights such as eHarmony, LinkedIn, Wired, Walmart, Sky, SitOrSquat, Northwestern Memorial Hospital, Many Moons

Grails Tooling

• Eclipse STS - much improved
• Unit test improvements - see test reports in console, run integration tests
• code completion, highlighting errors, gsp completion, tag attribute completion
• grails command window, auto completion, create apps wizard