Desired Capabilities are options or capabilities added for customising the Test Environment. There are a few capabilities that are common to all the Web Browsers whereas some are limited to a specific Browser. You can get more details about Desired Capabilities here - SeleniumHQ Desired Capabilities Github Page

In Testsigma, a couple of Desired Capability options are added by default for the ease of operation. In addition to this, sometime, Users need to add more capabilities to the execution to customise their Tests. They can do it for a specific Execution Configuration added under Executions.

Navigation: Test Development > Test Cases > Select Test Case >  Run Button

If you are creating a Dry Run right from the Test Case Details page, it will look as given below:

Navigation: Test Development > Executions > Create Executions >  Select Test Environment 

And if you are creating a normal Execution Configuration, it will look as given below:

Desired Capabilities are entered as Key : Value pairs.

Enter the details for Desired Capabilities as specified below:

Name: Enter the name of the capability. There are a set of predefined capabilities as given in the list of available Capabilities in the Next section

Data Type: The data type of the value of the specific Desired Capability.

Value: The value of the Desired Capability.

For example, we can add an extension or a set of extensions to the Automation Session by using the extensions Capability.

NameData TypeValue

For a single extension, use the form:

Here's are the links to some of the available Capabilities:

Desired Capabilities in Selenium | Appium Desired Capabilities | Capabilities & ChromeOptions

Please check the below guide for a walk-through on adding Chrome Extension as capability - How to add Chrome Extension to a session using Desired Capabilities

Happy Test Automation!