Sinon: Stub global variables

The modules I want to test and/or mock use some global variables.

For example, the source code of the module makes a reference to a variable session, which is not defined anywhere but is available at runtime.

Consider the module globals.js:

let globals = {
    contextName: "DATA_PIPELINE",
    reportContext: "report",
    session: session
};

module.exports = globals;

session is not defined in this file but available at runtime. It's a global variable of the environment (not under my control).

I notice that with fake timers, you've managed to replace the implementation of global functions such as setTimeout. How could we apply this to any global function/object?