karate\examples\gatling Project is not working throwing "java.lang.ClassNotFoundException: mock.CatsKarateSimulation" starting with gradle

[SergKV]

OS: Win 10 Pro
Gradle: Gradle 8.1.1
Gatling: 3.9.5
Java: openjdk 17.0.7 2023-04-18 LTS

Steps to reproduce:

1. clone git repo
2. navigate to folder -> "karate\examples\gatling"
3. run gatling test with "gradle gatling" or with "gradle gatlingRun" command

Result:
09:52:16.061 [main] ERROR io.gatling.app.Gatling$ - Run crashed
java.lang.IllegalArgumentException: User defined Simulation class mock.CatsKarateSimulation could not be loaded
at io.gatling.app.Selection$Selector.findUserDefinedSimulationInClassloader$1(Selection.scala:84)
at io.gatling.app.Selection$Selector.$anonfun$singleSimulationFromConfig$4(Selection.scala:88)
at scala.Option.orElse(Option.scala:477)
at io.gatling.app.Selection$Selector.$anonfun$singleSimulationFromConfig$3(Selection.scala:88)
at scala.Option.flatMap(Option.scala:283)
at io.gatling.app.Selection$Selector.singleSimulationFromConfig(Selection.scala:87)
at io.gatling.app.Selection$Selector.$anonfun$selection$1(Selection.scala:50)
at scala.Option.getOrElse(Option.scala:201)
at io.gatling.app.Selection$Selector.selection(Selection.scala:42)
at io.gatling.app.Selection$.apply(Selection.scala:35)
at io.gatling.app.Runner.run(Runner.scala:53)
at io.gatling.app.Gatling$.start(Gatling.scala:89)
at io.gatling.app.Gatling$.fromArgs(Gatling.scala:51)
at io.gatling.app.Gatling$.main(Gatling.scala:39)
at io.gatling.app.Gatling.main(Gatling.scala)
Caused by: java.lang.ClassNotFoundException: mock.CatsKarateSimulation
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:375)
at io.gatling.app.Selection$Selector.$anonfun$singleSimulationFromConfig$2(Selection.scala:73)
at scala.util.Try$.apply(Try.scala:210)
at io.gatling.app.Selection$Selector.findUserDefinedSimulationInClassloader$1(Selection.scala:73)
... 14 common frames omitted
Exception in thread "main" java.lang.IllegalArgumentException: User defined Simulation class mock.CatsKarateSimulation could not be loaded
at io.gatling.app.Selection$Selector.findUserDefinedSimulationInClassloader$1(Selection.scala:84)
at io.gatling.app.Selection$Selector.$anonfun$singleSimulationFromConfig$4(Selection.scala:88)
at scala.Option.orElse(Option.scala:477)
at io.gatling.app.Selection$Selector.$anonfun$singleSimulationFromConfig$3(Selection.scala:88)
at scala.Option.flatMap(Option.scala:283)
at io.gatling.app.Selection$Selector.singleSimulationFromConfig(Selection.scala:87)
at io.gatling.app.Selection$Selector.$anonfun$selection$1(Selection.scala:50)
at scala.Option.getOrElse(Option.scala:201)
at io.gatling.app.Selection$Selector.selection(Selection.scala:42)
at io.gatling.app.Selection$.apply(Selection.scala:35)
at io.gatling.app.Runner.run(Runner.scala:53)
at io.gatling.app.Gatling$.start(Gatling.scala:89)
at io.gatling.app.Gatling$.fromArgs(Gatling.scala:51)
at io.gatling.app.Gatling$.main(Gatling.scala:39)
at io.gatling.app.Gatling.main(Gatling.scala)
Caused by: java.lang.ClassNotFoundException: mock.CatsKarateSimulation
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:520)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:375)
at io.gatling.app.Selection$Selector.$anonfun$singleSimulationFromConfig$2(Selection.scala:73)
at scala.util.Try$.apply(Try.scala:210)
at io.gatling.app.Selection$Selector.findUserDefinedSimulationInClassloader$1(Selection.scala:73)
... 14 more

[ptrthomas]

@SergKV this example may indeed be out of date and we are more experienced with maven. please consider submitting a PR - meanwhile 1.5.X supports the Java option of Gatling instead of Scala - so see if that helps: https://github.com/karatelabs/karate-todo/tree/karate-1.5

[SergKV]

Thx a lot for instant reaction,
I'll spend some time playing with ideas which you just brought to table.
Going to to turn back and write my results here after some time.

[xloypaypa]

Just fixed that, the issue is:

1. the Scala code is not added as part of testing source code. So when you run the gatlingRun, it will not compile the scala files. So that's why gatling cannot found that class.
2. After added it to src. There are few grammar issues about scala. so just import required language packages.

[ptrthomas]

@xloypaypa merged with thanks !