Gatling fetching from csv file

Question

I have created a Gatling simulation, by creating a ".har" file from Google Chrome. And I have changed input parameters & trying to fetch data from a ".csv" file. Now when I run the simulation, how can I check if Gatling simulation has fetched data fields from ".csv" file?

Answer 1

Gatling has quite good error handling/logging connected to feeders.

1. When you provide wrong file name or path of your feeder file you will get following error (java.lang.IllegalArgumentException: Could not locate feeder file). Note that tests will not run.

   java.lang.reflect.InvocationTargetException
   at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
   at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
   at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
   at java.lang.reflect.Method.invoke(Method.java:498)
   at io.gatling.mojo.MainWithArgsInFile.runMain(MainWithArgsInFile.java:50)
   at io.gatling.mojo.MainWithArgsInFile.main(MainWithArgsInFile.java:33)
   Caused by: java.lang.IllegalArgumentException: Could not locate feeder file: file gatling/src/test/resources/data/wrongFile.csv doesn't exist
   at io.gatling.core.feeder.FeederSupport$class.feederBuilder(FeederSupport.scala:53)
   at io.gatling.core.Predef$.feederBuilder(Predef.scala:22)
   at io.gatling.core.feeder.FeederSupport$class.separatedValues(FeederSupport.scala:44)
   at io.gatling.core.Predef$.separatedValues(Predef.scala:22)
   at io.gatling.core.feeder.FeederSupport$class.separatedValues(FeederSupport.scala:41)
   at io.gatling.core.Predef$.separatedValues(Predef.scala:22)
   at io.gatling.core.feeder.FeederSupport$class.csv(FeederSupport.scala:34)
   at io.gatling.core.Predef$.csv(Predef.scala:22)
   at com.scenario.Scenario.<init>(Scenario.scala:10)
   at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
   at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
   at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
   at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
   at java.lang.Class.newInstance(Class.java:442)
   at io.gatling.app.Gatling$.io$gatling$app$Gatling$$$anonfun$1(Gatling.scala:41)
   at io.gatling.app.Gatling.run(Gatling.scala:92)
   at io.gatling.app.Gatling.runIfNecessary(Gatling.scala:75)
   at io.gatling.app.Gatling.start(Gatling.scala:65)
   at io.gatling.app.Gatling$.start(Gatling.scala:57)
   at io.gatling.app.Gatling$.fromArgs(Gatling.scala:49)
   at io.gatling.app.Gatling$.main(Gatling.scala:43)
   at io.gatling.app.Gatling.main(Gatling.scala)
   

2. When your attribute will not matched column name from feeder you will get following error. All tests will end with error.

   00:10:07.937 [ERROR] i.g.h.a.s.HttpRequestAction - 'httpRequest-1' failed to execute: No attribute named 'wrongAttributeName' is defined
   

3. When you have empty file with feeder data you will get following error.

   java.lang.reflect.InvocationTargetException
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at io.gatling.mojo.MainWithArgsInFile.runMain(MainWithArgsInFile.java:50)
      at io.gatling.mojo.MainWithArgsInFile.main(MainWithArgsInFile.java:33)
   Caused by: java.lang.IllegalStateException: Feeder is now empty, stopping engine
      at io.gatling.core.action.SingletonFeed$$anonfun$receive$1.applyOrElse(SingletonFeed.scala:61)
      at akka.actor.Actor$class.aroundReceive(Actor.scala:482)
      at io.gatling.core.akka.BaseActor.aroundReceive(BaseActor.scala:23)
      at akka.actor.ActorCell.receiveMessage(ActorCell.scala:526)
      at akka.actor.ActorCell.invoke(ActorCell.scala:495)
      at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:257)
      at akka.dispatch.Mailbox.run(Mailbox.scala:224)
      at akka.dispatch.Mailbox.exec(Mailbox.scala:234)
      at scala.concurrent.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
      at scala.concurrent.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
      at scala.concurrent.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
      at scala.concurrent.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
   

When non of this appear you can be almost sure that everything is ok. But to verify parameters send by Gatling you can check

1. Gatling logs (change logging level to DEBUG) in logback.xml

   <root level="DEBUG">
       <appender-ref ref="CONSOLE" />
   </root>
   

   And then you will see log similar to

   00:13:53.233 [DEBUG] i.g.h.a.s.HttpTx$ - Sending request=Action name uri=http://your-rest-service?param1=value1&param2=value2: scenario=com.scenario.Scenario Scenario name, userId=1
   

2. Access logs on your server. In Tomcat instruction you can get for example here

Answer 2

Temporarily lower logging level to DEBUG in conf/logback.xml, you'll see the requests that are being generated.