Lightweight Python Tests for use for in coding interviews

I'm looking for a lightweight way to unit test a function without using a library. Would love to hear a few ways to do this. Particular application is writing fast tests for coding interviews!

Something like: def foo(a,b): return a+b

tests = [(10,5), (2,7)]
testResults = [15, 9]

def test():
     results = list(map(foo, *tests))
     assert results == testResults