You must have created a dataset. Refer these steps to create variable.
Navigate to the Tests tab and click the Create New button.
Enter a Test Name in the designated field.
In the Describe Your Flow box, type your test steps in plain natural language.
To use a dynamic value, type {. Select Add variable from the dropdown menu, then choose the specific global variable you want to insert.
Click Save to finish creating the test.
Last updated 10 days ago