Enter the mind of an Agile Developer

Copyright BSG
BSG Grad Share 2014
Computer Science

Plan of Action
• Software Development at BSG
• What is Agile?
• Internal vs. External Quality
• Test Driven Development
(TDD)
• Behaviour Driven Development
(BDD)
• Ping Pong Pairing
• Our Testing Strategy (TDD /
BDD Hybrid)
• Demo

• Agile / Lean Development Methodology (JIRA Greenhopper)
• Architecture and Frameworks used Depend on the Project
 Conventional JSPs and Javascript libraries
 Google Web Toolkit (as used to write Google Wave)
 Tomcat (servlet container) or full application server
 JPA, Hibernate, Hibernate Search, Lucene
• Our Developers use Windows, Linux (Ubuntu) and Mac
• Development Tools
 IntelliJ IDEA or Eclipse IDE
 ANT for build scripts
 Junit, Hamcrest, Jmock and Jbehave for automated testing
 Jenkins for continuous integration
 Github for version control
 Team members are active contributors on global forums, such as
 A choice is made for each project
• Database is usually MySQL or client's choice (we have used Oracle quite often, for example)
Java Development at BSG

What is Agile?
• The highest priority of Agile is to satisfy the customer through early and
continuous delivery of valuable software
– Working software is the primary measure of progress of a project
• Common traits amongst agile methodologies include:
– Frequent product releases
– High levels of real‐time collaboration within the project team and with
customers
– Reduced time intensive documentation
– Regular, recurring assessments of value and risk to allow for change
The Agile Manifesto values:
 Individuals and interactions over processes
and tools
 Working software over comprehensive
documentation
 Customer collaboration over contract
negotiation
 Responding to change over following a plan

What makes a
code base agile?
• Properties:
 Lean (least quantity of code to get the job done)
 Well designed (modularised, layered)
 Tested (comprehensive testing strategy)
• Advantages:
 Easy to change without introducing regression issues/bugs
 Easy to maintain (localisation of issues through tests)
 Easy to understand (code = documentation, tests = specification)

• Internal quality determines your ability to
move forward on a project
• It is about “building software in the
right way” which is achieved through
white box testing (e.g. unit tests)
• Internal quality = all the properties of the
software as seen by the developers that
are desirable in order to facilitate the
process of creating a good product:
concision: code does not suffer from
duplication
cohesion: each module / class / routine does
one thing and does it well
low coupling: minimal interdependencies
and interrelation between objects
simplicity
generality: the problem domain bounds are
known and stated
clarity: the code enjoys a good auto
documentation level
• External Quality determines the fulfilment
of stakeholder requirements
• It is about “building the right software”
which is achieved through black box
testing (e.g. acceptance tests)
• External quality = all the properties of the
software as a product that users can
experience and enjoy:
conformity to their expectations (and
evolution thereof)
reliability
accuracy
ease of use and comfort (including response
delay)
robustness (or adaptability to some
unforeseen condition of use)
openness (or adaptability to future
extensions or evolutions)
Internal vs.
External Quality

Test Driven
Development
• Test-driven development (TDD) is a software development process that relies on the
repetition of a very short development cycle:
 First the developer writes an (initially failing) automated test case that defines a desired
improvement or new function
 then produces the minimum amount of code to pass that test
 and finally refactors the new code to acceptable standards
• Advantages:
 Reduced need to use debugger
 Test driven design (design for testability, “listen to the tests”)
 Incremental
 Faster
 Encourages modularisation and decoupling
 All paths through the code are tested

Behaviour Driven Development
• Behaviour-driven development is an
“outside-in” methodology
• It starts at the outside by identifying
business outcomes, and then drills down
into the feature set that will achieve those
outcomes
• Each feature is captured as a “story”,
which defines the scope of the feature
along with its acceptance criteria
• Ubiquitous domain language
• Non-technical / analytical techniques as
well, e.g. feature injection
• Advantages:
Better commitment and buy-in
Right focus
Evolutionary design
Breaking the knowledge silos in
distributed team
Greater ROI
Predictability & confidence

• Pair programming is an agile
software development technique
in which two programmers work
together at one workstation
One, the driver, writes code while the
other, the observer or navigator, reviews
each line of code as it is typed in
The two programmers switch roles
frequently
• Ping Pong Pairing (P3) combines
the concepts of TDD and Pair
programming, therefore mitigating
some of pitfalls while realising the
benefits of both
Better engagement from developers
Complete code coverage
Concision, least quantity of code to
get the job done
Reduced corner cutting
Ping Pong Pair
Programming

Our Testing
Strategy
A hybrid of BDD and TDD. We use a
combination of state and behaviour
verification.
Language through all tests uses the
same Domain Specific Language
(DSL).
Name tests in an intent revealing
way i.e. test<Method and fixture to
test>_should<Expected result>.

What tests do
we write?
• Acceptance tests
• Integration tests
 Query smoke tests
 Query semantics tests
 Round-trip tests
• Unit tests
 Presenter tests
 Service logic tests
 RPC service tests
• Regression tests

A Layered
Architecture
• Presentation layer
 MVP to allow for testing this layer
• Service layer
 Mock out lower layers
• Persistence layer
 Interact with the DB)

Model View Presenter (MVP)
• A design pattern which facilitates unit testing:
 The model contains the data to be handled by the
presenter and displayed in the view.
 The view simply displays data passed to it from the
presenter, and routes events from the user back to
the presenter.
 The presenter fetches data (the model), performs the
required logic with that data, and passes it to the view
to be displayed.

Mocking
• We use JMock
 Behaviour verification
 Fake dependencies
 Return expected values without touching layers below
• Some other popular mocking frameworks include:
 Mockito
 EasyMock

Helpers
Builders - construct and
persist domain objects to be
used in tests.
Matchers - to make
assertions and compare
the state of objects.

• Developers run tests locally before
pushing changes
• Our Continuous Integration (CI)
server runs the tests as well
• We use Jenkins CI
• A build is triggered when code is
pushed to GitHub
• Jenkins compiles the code and
runs all tests
• If any tests fail a notification email
is sent to the team
Running Tests

Testing and Code
Coverage Demo

References
• http://agilemanifesto.org/
• http://c2.com/cgi/wiki?InternalAndExternalQuality
• http://meekrosoft.wordpress.com/2010/10/31/internal-and-external-software-quality
• http://en.wikipedia.org/wiki/Test-driven_development
• http://en.wikipedia.org/wiki/Behavior_Driven_Development
• http://dannorth.net/
• http://blogs.agilefaqs.com/2012/11/11/benefits-of-behavior-driven-development-bdd/
• http://en.wikipedia.org/wiki/Pair_programming
• http://behave.readthedocs.org/en/latest/philosophy.html

Social media - keep in touch
#2014GradShare #AgileDev

Enter the mind of an Agile Developer

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