If yocto-compat-layer-wrapper is run against a layer, which depends on another layer. The dependent layers are not resolved and the tests fail (no bb recipes are found for bbappends in our layer).
I have no idea what 'yocto-compat-layer-wrapper' is. yocto-compat-layer, formerly yocto-compat-layer.py, does properly handle dependencies. The dependency must be specified in the layer.conf file using LAYERDEPENDS = "..." The dependency layers must be provided to the tool using the command line --dependency <path> arguments, or included in the primary checking argument. Without doing this the tool has no way to 'find' a layer. You must tell it where everything else.
Per Todor, mark as resolved. --dependency works for him.