In order to start writing automated tests on your AL extension, you need to import Microsoft Test Framework into your Dynamics 365 Business Central environment. If you're working with Dynamics 365 Business Central on-premise (standalone installation), you can import it from the product DVD. If you are using a Docker-based development sandbox, you can import the Test Toolkit automatically with the navcontainerhelper module by adding the -includeTestToolkit switch parameter to the New-BcContainer cmdlet.
If you have an already-running Docker container with Dynamics 365 Business Central, you can import the Test Toolkit by using the following cmdlets:
Import-TestToolkitToBcContainer -containerName d365bcdev Generate-SymbolsInNavContainer -containerName d365bcdev
The Test Toolkit Test Libraries consist of the following...