Agile TESTING Practices ON THE Java

Platform Creative development in principle

Peter Pilgrim Scala and Java EE

Independent contractor

@peter_pilgrim  

uk.linkedin.com/in/peterpilgrim

2000/  

Xenonique

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About Me •  Scala and Java EE developer independent

contractor •  Digital transformation GOV.UK •  Java Champion •  Working on the JVM since 1998

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Java EE 7 Developer Handbook September  2013  Packt  Publishing    Digital Java EE 7 Web APPS December  2014  

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•  TDD •  Java Technology •  Creative

Development in Principle

•  Scala Technology

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Is TDD Dead? •  TDD is Dead, Long Live Testing Blog article by David Heinemeier Hanson http://david.heinemeierhansson.com/2014/tdd-is-dead-long-live-testing.html

•  Series of 5 Google Hangout Videos @dhh, @kentbeck and @martinfowler http://martinfowler.com/articles/is-tdd-dead/

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“I rarely unit test in the traditional sense of the word, where all dependencies are mocked out, and thousands of tests can close in seconds. It just hasn't been a useful way of dealing with the testing of Rails applications.” D.H.H

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JUnit  

the  mother    of  all  unit  tesFng  frameworks  

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#1 Java unit testing framework on the JVM. Other alternate languages have variants or interoperability.

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2007 JUnit 4.4

XMLUnit, DBTest, HTMLUnit, PerfTest, EasyMock, Test NG, Cactus, SoapUI

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2014 - JUnit 4.12?

Mockito, Concordion, Spring, JMock, Arquillian, Fit/Fitnesse, JBehave, ScalaTest, Spock

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JUnit Test Example #1

import org.junit.*; import static org.junit.Assert.assertThat; import static org.hamcrest.CoreMatchers.*; public class ForexTradingDeskTest { TradingDesk desk = new ForexTradingDesk(); /* ... */ }

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JUnit Test Example #2

public class ForexTradingDeskTest { @Before public void setUp() { desk.acquire(); } @After public void tearDown() {

desk.release(); } /* ... */ }

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Java Test Example #3

@Test public void shouldExecuteTrade() { Trade trade = ForexTrade("GBP","EUR", 10000); desk.execute(trade); assertThat( trade.getStatus(), is(Executed)); }

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These tools were built for the mother language of the Java Virtual Machine.

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Sadly, these tools do not work too with:

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Three development concepts for agile digital applications

Efficiency   Design     Human  Nature  

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#1 Understanding the Efficiency of our Java application development

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30.7% Github projects* have a dependency on JUnit. Yet we, Java developers, still write too much boilerplate, over-engineer design patterns.

We forget about directing the future. *http://www.takipiblog.com/we-analyzed-30000-github-projects-here-are-the-top-100-libraries-in-java-js-and-ruby/

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Hard-­‐coded  dependencies  and  unassailable  fixtures  are  the  issues.  It  does  not  maNer  which  technology.  

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Technology is not the problem. How much do we understand design and architecture?

Java is a programming language. Java is a virtual machine. Java is a platform.

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#1 Completeness: As digital transformation engineers, what would happen to admitted: we can never have 100% coverage complete with just unit-tests?

What are we measuring? How are we measuring? Impossible to prove all branches in a program

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#1 Efficiency: Prefer to write tests than none at all Prefer to mock out dependencies Prefer to test the simplest thing possible

Avoid duplication (cut and paste tests) Reduce fixtures and preconditions

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#1 Efficiency: Prefer integration tests over unit tests. Remove unit tests that over time are always ”green”. Rely on functional and acceptance tests as well.

Hire a developer-in-test into your team Avoid being a unit-test automaton.

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#2 The age-old issue of how do we Design? Time, space and cost are constants

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“TEX would have been a complete failure if I had merely specified it and not participated fully in its initial implementation. The process of implementation constantly led me to unanticipated questions and to new insights about how the original specifications could be improved.” Donald Knuth

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#2  Design  Test-­‐First  may  be  harmful  True  design  presupposes    we  have  ability  to  escape  restric@ons.  It  requires  to  innovate  around  the  architectural  boundaries.  

Edit  -­‐>  Compile  -­‐>  Test  -­‐>  Refactor    

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#2  Design  Our  problem  is  abstrac@on  “Debugging  is  not  what  you  do  when  you  fire  up  the  debugger.  It  is  when  you  lie  back  in  the  chair  and  look  at  the  ceiling.”  

Crea@vity  is  a  thought  process  

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#2  Design  –    Problem  solving  versus  art  Balance  crea@vity  whilst  respecFng  produc@vity  and  testability  

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#2  Design  –  search  the  Internet  for  a  video  

Bret  Victor,  Inven@ng  on  Principle  

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#3 Human Nature It’s always about the folk. How long did it take to learn this simple truth in computer science?

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#3 Human Nature Now it is about everyone on the planet We are serving the digital customers for all the screens of our lives

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#3 Human Nature Developers require UX education. We cannot afford to not invest in learning. Digital transformation is open for all people.

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#3 Human Nature

“He said it was more important that the company avoid the appearance of having done something wrong than that we stop before producing an incorrect result. I left the company.“

Jim Coplien, Why Unit Testing is a Waste hNp://www.rbcs-­‐us.com/documents/Why-­‐Most-­‐Unit-­‐TesFng-­‐is-­‐Waste.pdf  

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#3 Human Nature Good developers are generally good writers. Great developers can create AM #1: “Interactions and individuals over processes and tools”

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Scala Test #1

import collection.mutable.Stack import org.scalatest._ class StackSpec extends FlatSpec with Matchers { /* ... */

}

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Scala Test #2

class StackSpec extends FlatSpec with Matchers { "A Stack" should "pop values in last-in-first-out order" in { val stack = new Stack[Int] stack.push(1) stack.push(2) stack.pop() should be (2) stack.pop() should be (1) } /* ... */ }

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Scala Test #3

class StackSpec extends FlatSpec with Matchers { /* ... */ it should "throw NoSuchElementException if an empty stack is popped" in { val emptyStack = new Stack[Int] a [NoSuchElementException] should be thrownBy {

emptyStack.pop() } } }

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How to avoid null pointers in Scala Programming?

val greeting1: Option[String] = Some("AOTB14") val greeting2: Option[String] = None

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Pattern Matching

def checker(p : Option[String]): String = { p match { case Some(v) => v case _ => "Unexpected" } } checker(greeting1) // "Hello AOTB14" checker(greeting2) // "Unspecified"

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Scala’s generic immutable list collection type

val list: List[Int] = List(1,2,3,4) list.foreach { x => println(x) } // 1,2,3,4

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Scala’s option behaves like collection type #2

greeting1.foreach { x => println(s"Work: ${x}" ) } // Work: Hello AOTB14

greeting2.foreach { x => println(s"Work: ${x}" ) } // *** nothing happens ***

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Read, Evaluate, Print, Loop •  Scala, Clojure, Groovy, Kotlin, Ceylon, Fantom All have a interpretative mode •  Java JDK does not (yet) have an official REPL (However try out javarepl.com online) •  Fingers crossed Project Kulla in JDK 9 http://blog.gmane.org/gmane.comp.java.openjdk.general

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#DailyWork2014 GOV.UK •  Develop Scala applications •  Play Framework, RESTful Services, MongoDB •  Cucumber testing: acceptance & functional •  Collaborative design, pairing and reviews •  SCRUM, Sometimes Kanban •  Physical storyboards, retros, planning •  Heavy dose of UX / User Centric •  Government Digital Service

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•  TDD •  Java Technology •  Creative

Development in Principle

•  Scala Technology

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Recipe for Success

• Be creative and artistic again •  Leave a digital legacy of achievement •  Be efficient, evolve design and aware of

human nature

•  Invent your own principles

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@peter_pilgrim  

uk.linkedin.com/in/peterpilgrim

2000/  

Xenonique

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