What to set up in a Kernel test to get custom content type to be available
For kernel tests you need to specify which configurations you want installed. For instance, you'll need something like this in your test's setUp() method:

$this-&gt;installConfig(['my_custom_module']);


That takes an array of modules, so you'll probably need to specify additional modules (like filter, node, and field potentially).

This assumes your field configurations are bundled in your module's config/install directory.