Scala Code quality assurance by Roch Delsalle ScalaDays Berlin 2014 @D_Roch 

about me and Mister Bell Scala lead developer Specialist in REST API Specialist in continuous integration Code alchemist Roch Delsalle Leader in performance and mobile affiliation in Europe, Latin America and the region of the Middle East. 

what is a quality assurance process? yes, what is it ? Simply, the Automation of repetitive quality check tasks my slime is quality! Don’t laugh, 

Why it is worth it ? for safe production! 

it’s at your own risk in production! 

Why it is worth it? coding without bugs, really? Fail early... not in production Avoid repetitive tasks Increase your deployment velocity 

Continuous Integration the runner Jenkins Fork of Hudson M.I.T. License Self hosted solution Open source gitlab Self hosted solution Open Source travis Hosted solution Open Source 

Code Coverage techniques definition Line level coverage Branch level coverage Statement level coverage is always under construction T he road to success… 

statement level coverage Cover it all ! val status = if (age < 18) "No beer" else "Beer for you” If you test: age = 18 You would get: ! Lines covered : 100 % Statements covered : 50 % Doh! a free beer? 

Line level VS Branch level ready? fight! ! 4 out of 5 lines covered : 80 % 1 out of 2 branches covered : 50 % ! if(cond) { 
 line1 
 line2 
 line3 
 line4 
 } else { 
 line5 
 }
 If your test only goes in the cond being true and never runs the else branch : You would have: 

Statement level coverage vs Branch round 2, fight! ! Statements covered : 100 % Branches covered : 50 % 
 def testMe(cond1:Boolean, cond2:Boolean) = { 
 if (cond1) line1()
 if (cond2) line2()
 }
 If your test only goes in the cond1 being true and cond2 being true: You would have: In order to get 100% branches covered, you will have to add a test with cond1 and cond2 as false 

BRANCH LEVEL COVERAGE going everywhere If / else statements Match statements Partial function cases Try / catch / finally clauses 

Scala code coverage Tools recap SCCT jacoco4sbt Scoverage line level coverage YES YES YES statement coverage NO NO YES branch coverage NO YES YES Instrumentation AST Bytecode AST need some beer… 

Bytecode instrumentation Let’s rock! Using JVM Java Agent Done natively in the VM Notified at runtime when a statement is execution 

Abstract syntax tree Scala’s way Need to write temporary files Runtime bytecode instrumentation works well for Java … not for Scala 

scoverage, the modular choice scalability SCOVERAGE SCALA CODE COVERAGE scoverage.org github.com/scoverage Samuel Stephen https://github.com/sksamuel 

Code instrumentation input Go on, Maestro! SBT Scala Build Tool GRADLE Build automation MAVEN Software project management 

Code quality inspection HTML output 

Code quality inspection XML output 
 
 
 /scoverage-samples/src/main/scala/com/sksamuel/scoverage/samples/Platform.scala
 com.sksamuel.scoverage.samples
 Platform
 Class
 <none>
 137
 374
 374
 12
 akka.actor.Props.apply({
 scoverage.Invoker.invoked(135, "/scoverage-samples/target/scala-2.11/scoverage-data");
 classOf[com.sksamuel.scoverage.samples.OrderEngine]
 }, {
 scoverage.Invoker.invoked(136, "/scoverage-samples/target/scala-2.11/scoverage-data");
 Platform.this.creditEngine
 })
 akka.actor.Props.apply
 

Code quality inspection One more thing… SonarQUBE Scala Sonar Tool Line level coverage Sonar Scoverage Plugin Statement level coverage Branch level coverage + SCOVERAGE SCALA CODE COVERAGE = Radoslav Buranský http://buransky.com 

Code quality inspection results & interfaces 

External tools integration Sing sing sing PASSED WAITING FAILED GOD mode on Let’s pray What? no way! 

Possible workflow it’s your choice SCOVERAGE SCALA CODE COVERAGE build result analysis 

industrialisation don’t reapeat yourself Generate docs Generate API results for frontend developers 

deployment INDUSTRIALISATION put your hands in the air Magenta/Riff-Raff : The Guardian's scala-based deployment lib OR Capistrano-sbt 

Thank you any questions? ScalaDays Berlin 2014 @D_Roch 

Further reading keep the track!