When a node needs test data, is it possible to allow custom test data?

The idea is:

When I click to insert test data in the node’s output panel, I can call the test data interface I wrote in the node, instead of all nodes simply returning the same predefined data format.

My use case:

When I use a node created by others, I don’t know what the output format of this node is. I can only get the data format after executing this node correctly once, which makes it impossible for me to continue to create subsequent nodes. . If we provide an interface for custom test data, I can return predictable and correct results from the node when inserting the test data, so that I can continue to create subsequent processes.