open Jest
open Expect
let {eval} = module(Parser_Squiggle)

describe("expressions of normal distributions:", () => {
  test("sum of two", () => {
    expect(eval(" normal (5 , 2 ) + normal(0,2)"))->toEqual(
      {mean: 5.0 +. 0.0, stdev: Js.Math.sqrt(2.0 ** 2.0 +. 2.0 ** 2.0)}
      ->#Normal
      ->Symbolic
      ->EvDistribution
      ->Ok
      ->Some,
    )
  })
  test("difference of two", () => {
    expect(eval("normal(5,3)-normal(2,1)"))->toEqual(
      {mean: 5.0 -. 2.0, stdev: Js.Math.sqrt(3.0 ** 2.0 +. 1.0 ** 2.0)}
      ->#Normal
      ->Symbolic
      ->EvDistribution
      ->Ok
      ->Some,
    )
  })
  test("product of two", () => {
    let item = eval("normal ( 5 , 3 ) * normal(2,1)")
    exception NotOk(string)
    let item' = switch item {
    | Some(Ok(EvDistribution(SampleSet(x)))) => x
    | _ => raise(NotOk("something happened"))
    }
    expect(Js.Array.length(item'))->toEqual(10000)
  })
})