Talk delivered by Craig Smith and Paul King at Agile 2008 in Toronto, Canada on 7 August 2008. Developer practices for traditional and agile Java development are well understood and documented. But dynamic languages - Groovy, Ruby, and others - change the ground rules. Many of the common practices, refactoring techniques, and design patterns we have been taught either no longer apply or should be applied differently and some new techniques come into play. In this talk, techniques for agile development with dynamic languages are discussed. How should we better apply refactoring techniques? What new aspects do we need to think about?

1. ©ASERT/Suncorp2006-2008
Technical lessons learned
turning the agile dials to eleven!
Dr Paul King
ASERT, Australia
Craig Smith
Suncorp, Australia
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2. ©ASERT/Suncorp2006-2008
Topics
• Introduction
• Quality Metrics
• Dealing with Boundaries
• Easing the
mocking burden
• Instance providers
• Autochecking
• Atoms, Molecules and
disposable tests
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3. Introduction
• Initial goals (dials to ten)
– 100% code coverage from unit tests
– All production code paired and test-driven
– Minimal design up front but an appreciation
for when such design made sense
– Customer focused outcomes
– Full continuous integration
– Daily pair rotation
– Continuous improvement through retrospectives
– High levels of automation
– Light-weight metrics to monitor progress
• Now how can we crank the dials further?
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4. Agile 2008 - 4
Quality Metrics
• Duplication
– 0% duplication or build breaks (threshold = 4 lines)
• Now cranking back this metric for acceptance tests
• Method and Class Complexity
– Extremely simple classes and code
• Rarely used escape mechanism
• Graph true exceptions over time
• Method and Class Size
– Approx 10 lines per method, 80 lines per class
• 5-7 lines led to Ravioli code so we cranked this back
• Still hard to do try … catch … finally
but for us that need mostly occurs in boundaries
• To split 50 lines, use approx 7 methods of 7 lines not
two 25-line methods or twenty five 2-line methods
©ASERT/Suncorp2006-2008

5. Dealing with Boundaries
• Boundaries used with 3rd party APIs
• Ways to create
– IDE plugin to create static boundaries
– Groovy to automatically eliminate checked
exceptions through a language feature
– Use autoboundaries of an interface
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package autoboundary.java.io;
public interface File {
String getCanonicalPath();
}
public class FileBoundary {
private File delegate;
public String getCanonicalPath() {
try {
return delegate
.getCanonicalPath();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}

6. Easing the mocking burden…
• Mocking became a pain point
– JMock 1 style mocking, small classes, 100% test
driven, rampant refactoring
• Want to avoid boiler plate set up of tests
– Instead of this:
– Have ‘magic’ framework allowing auto mock creation
• Based on most specific constructor matching fields
• Using naming conventions or annotations (shown):
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private DocumentProperties docProps;
private DocumentReader reader;
private WordCounter counter;
@Before public void before() {
reader = context.mock(DocumentReader.class);
counter = context.mock(WordCounter.class);
docProps = new DocumentPropertiesImpl(reader, counter);
}
@Subject DocumentPropertiesImpl docProps;
@Mock DocumentReader reader;
@Mock WordCounter counter;

7. …Easing the mocking burden
• Avoid cumbersome expectation DSL:
– Not this:
– Instead this:
– Then have IDE support to convert between the two:
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expectOneCallTo("getName", mockAuthor)
.will(returnValue(name));
name = author.getName();

8. Instance providers
• Instance/mock creation (annotations):
• Also have auto instance provider (naming
convention example):
– POJOs generated recursively or overridden using
numerous other conventions Agile 2008 - 8
©ASERT/Suncorp2006-2008
@Subject(auto=false) DocumentPropertiesImpl docProps;
@Mock private DocumentReader reader;
@Stub private String fileName;
@Wired private DocumentWriter writer;
String uniqueStringA;
String uniqueStringB;
Summer subject = new Summer();
public void testSumStringsAutoTriangulation() {
assertEquals(
uniqueStringA + uniqueStringB,
subject.sum(uniqueStringA, uniqueStringB));
}

9. Autochecking
• Numerous checks built in to testing
framework
– Auto null checking for public
methods and public constructors
– Auto check getters and setters
– Particular project-wide rules to
do with final, equals, hashCode
(not covered by checkstyle)
• Numerous types of classes had further
checks
– Immutable
– Serializable
– Components (remotable)
– Data (non-persistent POJO)
– Domain (persistent POJO)
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10. Atoms, Molecules and disposable tests
• Deleting tests that don’t pull their weight:
– Distinguish between atoms and molecules
– Only support reuse at the molecular level
– Require 100% test coverage at the molecular level
– Can safely discard atomic interaction-based unit tests
• IDE automation allows them to be recreated trivially
– Allow state-based atomic tests to be kept if desired
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11. Stage 2 Velocity
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ScopeinIdealDeveloperHours
Schedule in Iterations
Release 7 Burn-Up Chart Burn-Up

12. Future Directions
• Acceptance-TDD or Functional-TDD
when appropriate
– Grails, Tester and Customer involvement
• Evolve how we use TDD & CI
– Disposable Atomic Tests, Groovy,
BDD, EasyB, Instinct, Performance
• Leverage a broader base
of testing approaches
– Jester, AllPairs, Reductio, Theories, Exploratory, Grids
• Further use of DSLs
– Testing, Business Rules, Workflows, Configuration
• Further use of more powerful languages
– Groovy, Scala, Ruby, Polyglot programming
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13. About the contributing organizations
• About ASERT
– ASERT helps organisations define and make best use of their
eBusiness platforms by providing professional and cost-
effective training and consulting & system development
solutions including but not limited to Agile development,
Java/J2EE development, Groovy and Grails development, SOA
and web services implementations and agile deployment.
• About Suncorp
– Suncorp is one of Australia and New Zealand's largest
diversified financial services providers, supplying banking,
insurance and wealth management products to around 7 million
customers through well-established and recognized brands
such as AAMI, Australian Pensioners Insurance Agency,
Shannons, Vero, Asteron and Tyndall, as well as Suncorp and
GIO. Today, Suncorp is Australia's sixth largest bank and
second largest domestic general insurance group, with over
16,000 staff. Suncorp has representation in 450 offices,
branches and agencies throughout Australia and New Zealand.
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©ASERT/Suncorp2006-2008