Spek documentation references
As a best practice you typically want test values to be unique for each test this can be done by using a lateinit variable and assigning it within a beforeEachTest. lateinit var calculator: Calculator
beforeEachTest {
calculator = Calculator()
}
To make it more concise, Spek provides memoized to do the same thing:
val calculator by memoized { Calculator() }
What exactly is memoized?
Memoization is remembering (caching) the result of a function call with a given set of parameter values so that if that same function is called again with the same parameter values, the cached result will be returned rather than having to re-run the function. It's an optimisation technique.
See more info here: https://en.wikipedia.org/wiki/Memoization
So in the example above Spek wraps the call to construct a Calculator in its memoized function, meaning that it will only construct it once, and thereafter calls to calculator will re-use that existing instance. And in terms of how you'd generally use it in a test, that would give you the same behaviour as constructing a new Calculator in beforeEachTest, but in a more concise way.
