1. A method, comprising: executing in a virtual machine execution environment at least a portion of application code comprising an application; observing programmatically an interaction between the application code executing in the virtual machine execution environment with a data entity included in a set of production data; determining a minimal subset of production data that is minimally sufficient to enable testing of the application code based on the observed interaction between the application code and the data entity; including in a data transfer guide at least in part programmatically a data that represents the data entity; determining that the application code executing in the virtual machine execution environment is attempting to make a change to a production data value associated with the data entity; and storing data reflecting the change in a shadow data store associated with the virtual machine execution environment and not in the set of production data.