JMeter Random Variable Element not recognise variable from previous step

Question

tl;dr When I use my variable created in Regular Expression Extractor I cannot use it in Random Variable as Maximum Value

Long description:

• My test structure:
  • 
• I have variable my_test what is crated in Regular Expression Extractor
  • request: GET //echo.getpostman.com/get?test=123
  • regex:
  • 
• Then I want it use as Maximum Value in Regular Expression Extractor
  • 
• So finally I can make request:
  • //echo.getpostman.com/get?test=${rand}

Unfortunately I get error from Random Variable
2016/10/07 07:52:41 ERROR - jmeter.config.RandomVariableConfig: maximum(${my_test}) must be > minimum1)

Why my_test is not evaluated?

I have tried ${__javaScript(parseInt('${my_test}'))} but it looks like it is evaluated before my variable initialization 2016/10/07 08:06:01 ERROR - jmeter.config.RandomVariableConfig: maximum(NaN) must be > minimum1)
If I initialize this variable in Test Plan in User Defined Variables value from that setting will be used - not updated by regex.

I know that I can do //echo.getpostman.com/get?test=${__Random(0,${my_test})}
I'm just curious how pass my variable as value for Maximum Value in Regular Expression Extractor.

Answer 1

It seems that Random Variable element does not evaluate variables, maybe it worth creating an issue in JMeter Issue Tracker

As a workaround you can substitute it with __Random() function directly where required like:

• ${__Random(1,${my_test},)} - if you need the value right away, directly in you URL:

  //echo.getpostman.com/get?test=${__Random(1,${my_test},)}
  

• ${__Random(1,${my_test},rand)} - if if you need to store the value into ${rand} variable as well

See:

• Using JMeter Functions article for extended information on this and others JMeter Functions.
• Function Helper Dialog - an utility helping to generate correct function syntax.

Answer 2

I think it's valid for me to comment on a problem I had, I set the random variable and it didn't work at all, I did everything I could to try to solve it. In the end my problem was a space at the beginning of the variable.

Answer 3

One possibility is you can use a Beanshell Postprocessor to write the RegEx value to the variable name. After that you can use it as ${variable_name}

NB: Beanshell function vars.get can be used for getting regex value and vars.put can be used for putting it into your variable.