You should check out the sinon.match api (http://sinonjs.org/docs/#sinon-match-api)
Using sinon.match.func your example above would become:
var serviceFunction = this.spy(); // or `sinon.spy()`
var functionUnderTest = create(serviceFunction);
var thing = 'arbitrary/thing'
functionUnderTest(thing);
assert.calledWith(thing, sinon.match.func);