Scala Code Quality Assurance - ScalaIO Paris

ScalaIO 2014 - Paris
Roch Delsalle
Mister Bell

Transcript

1. Scala Code quality assurance by Roch Delsalle Scala io Paris 2014 @D_Roch
2. 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.
3. 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,
4. Why it is worth it ? for safe production!
5. it’s at your own risk in production!
6. Why it is worth it? coding without bugs, really? Fail early... not in production Avoid repetitive tasks Increase your deployment velocity
7. 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
8. Code Coverage techniques definition Line level coverage Branch level coverage Statement level coverage is always under construction T he road to success…
9. 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?
10. 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:
11. 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:
12. 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
13. BRANCH LEVEL COVERAGE going everywhere If / else statements Match statements Partial function cases Try / catch / finally clauses
14. 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…
15. Bytecode instrumentation Java only Using JVM Java Agent Done natively in the VM Notified at runtime when a statement is execution
16. Bytecode instrumentation Java only Scala bytecode output is more complex Not reliable for instrumentation
17. Bytecode instrumentation Java only Let’s say you are using line level coverage for this example You write two lines of Scala 1rst line compiles to 100 bytecodes 2d line compiles to 10 bytecodes If you have only tested line 2 you would get 9% coverage, when it should be 50%
18. Abstract syntax tree Scala’s way Need to write temporary files Runtime bytecode instrumentation works well for Java … not for Scala
19. scoverage, the modular choice scalability SCOVERAGE SCALA CODE COVERAGE scoverage.org github.com/scoverage Samuel Stephen https://github.com/sksamuel
20. Code instrumentation input Go on, Maestro! SBT Scala Build Tool GRADLE Build automation MAVEN Software project management
21. Code quality inspection HTML output
22. Code quality inspection XML output <?xml version="1.0"?>
 <statements>
 <statement>
 <source>/scoverage-samples/src/main/scala/com/sksamuel/scoverage/samples/Platform.scala</source>
 <package>com.sksamuel.scoverage.samples</package>
 <class>Platform</class>
 <classType>Class</classType>
 <method>&lt;none&gt;</method>
 <id>137</id>
 <start>374</start>
 <end>374</end>
 <line>12</line>
 <description>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
 })</description>
 <symbolName>akka.actor.Props.apply</symbolName>

23. Static Code AnalYSERS results & interfaces • Scapegoat • FindBugs • checkstyle • ScalaStyle
24. Code quality inspection results & interfaces SonarQUBE Scala Sonar Tool https://github.com/SonarCommunity/sonar-scala
25. Code quality inspection results & interfaces
26. Code quality inspection Sonar Scoverage Plugin Statement level coverage Branch level coverage + SCOVERAGE SCALA CODE COVERAGE = Radoslav Buranský http://buransky.com results & interfaces
27. Possible workflow it’s your choice SCOVERAGE SCALA CODE COVERAGE build result analysis
28. Possible workflow our choice SCOVERAGE SCALA CODE COVERAGE build result analysis Scala Backend JS FRONTEND
29. Code quality inspection results & interfaces
30. External tools integration Sing sing sing PASSED WAITING FAILED GOD mode on Let’s pray What? no way!
31. industrialisation don’t reapeat yourself Generate docs Generate API results for frontend developers
32. deployment INDUSTRIALISATION put your hands in the air capistrano-sbt Deploy your apps To any number of machines https://github.com/yyuu/capistranosbt
33. deployment INDUSTRIALISATION put your hands in the air Magenta/Riff-Raff : The Guardian's scala-based deployment lib OR Capistrano-sbt
34. Thank you any questions? @D_Roch Scala io Paris 2014