Variables

All but the simplest scenarios will use session variables. Hyperfoil sports steps that generate values into these variables (randomInt, randomItem, …), processors that write data from other sources to variables (store, array) and many places that read variables and use the values to perform some operations (httpRequest.path ) or alter control flow.

Hyperfoil uses different types of variables (slots in the session) for integer variables and generic objects (commonly strings). When a numeric value is received as a string (e.g. when parsing response headers) and you want to use it in a step that expects exclusively integral values you have to convert it explicitly, e.g. using the stringToInt action. Steps that read values to form a string can usually consume both types of variables, without any need for conversion.

Besides user-defined variables there are some read-only pseudo-variables that can be used in the scenario as if these were regular variables:

String interpolation

Components that accept string values usually allow you to use a pattern - parts of the string can be replaced in runtime with the value from a session variable. A simple example of pattern would be The quick brown ${wild-animal} jumps over the lazy ${domestic-animal} - variables wild-animal and domestic-animal would get replaced with their respective values.

When you really want to use ${wild-animal} in a value for such component you should escape it with one more dollar sign: This $${variable} won't be replaced will be rendered into This ${variable} won't be replaced.

There are a few transformations that you can perform with a variable value while interpolating the pattern:

• ${urlencode:my-variable} will replace characters in the my-variable using URLEncoder.encode (using UTF-8 encoding).
• ${{ '{%05d' }}:my-number} and other formatter strings ending with d, o, x or X will convert an integer variable using Formatter.
• ${replace/<regexp>/<replacement>/<flags>:my-variable} perform Java regexp replacement on my-variable contents. Note that you can use any character after replace, not just / - this becomes the separator between regexp, replacement and flags. The only flags currently supported is g - replacing all occurences of that string (by default only first occurence is replaced).

Sequence-scoped access

When an array or collection is stored in a session variable you can access the individual elements by appending [.] to the variable name, e.g. my-variable[.]. You can see that we don’t use the actual index into the array: instead we use current sequence instance index. You can read more about running multiple sequences concurrently in the Architecture/Scenario Execution.