Click test plan add a new variable with name = tool and value = jmeter. Since this value is defined at Test Plan level so it is available to all threads we create in our test plan.

Add a new thread group

Add a if controller.And two requests to this controller.In if controller in Condition(Default Javascript) type

 "${tool}"=="jmeter"

And a new Debug sampler to the thread group as well.

Then if we run the test plan it will execute both the tests as x declared in test plan is equal to jmeter and so value given in if condition is true.

If we try something like this

 "${tool}"=="loadrunner" 

The respnse data of debug sampler defined after the if loop can we used to check the actual value of tool variable.