LispInSmallPieces/test/test_chapter3.coffee

chai = require 'chai'
chai.should()
expect = chai.expect

{cons} = require "cons-lists/lists"
olisp = require '../chapter3/interpreter'
{read, readForms} = require '../chapter1/reader'

the_false_value = (cons "false", "boolean")

lisp = (ast) ->
  ret = undefined
  olisp ast, (i) -> ret = i
  return ret


describe "Core interpreter #3", ->
  it "Should handle true statements", ->
    expect(lisp read "(begin (if (lt 0 1) #t #f))").to.equal(true)
  it "Should handle false statements", ->
    expect(lisp read "(begin (if (lt 1 0) #t #f))").to.deep.equal(the_false_value)
  it "Should handle return strings", ->
    expect(lisp read '(begin (if (lt 0 1) "y" "n"))').to.equal("y")
  it "Should handle return strings when false", ->
    expect(lisp read '(begin (if (lt 1 0) "y" "n"))').to.equal("n")
  it "Should handle equivalent objects that are not intrinsically truthy", ->
    expect(lisp read '(begin (if (eq? "y" "y") "y" "n"))').to.equal("y")
  it "Should handle inequivalent objects that are not intrinsically truthy", ->
    expect(lisp read '(begin (if (eq? "y" "x") "y" "n"))').to.equal("n")

  it "Should handle basic arithmetic", ->
    expect(lisp read '(begin (+ 5 5))').to.equal(10)
    expect(lisp read '(begin (* 5 5))').to.equal(25)
    expect(lisp read '(begin (/ 5 5))').to.equal(1)
    expect(lisp read '(begin (- 9 5))').to.equal(4)

  it "Should handle some algebra", ->
    expect(lisp read '(begin (* (+ 5 5) (* 2 3)))').to.equal(60)

  it "Should handle a basic setting", ->
    expect(lisp read '(begin (set! fact 4) fact)').to.equal(4)

  it "Should handle a zero arity thunk", ->
    expect(lisp read '(begin (set! fact (lambda () (+ 5 5))) (fact))').to.equal(10)

  it "Should handle a two arity thunk", ->
    expect(lisp read '(begin (set! fact (lambda (a b) (+ a b))) (fact 4 6))').to.equal(10)

  it "Should handle a recursive function", ->
    expect(lisp read '(begin (set! fact (lambda (x) (if (eq? x 0) 1 (* x (fact (- x 1)))))) (fact 5))').to.equal(120)

  it "Should handle an IIFE", ->
    expect(lisp read '(begin ((lambda () (+ 5 5))))').to.equal(10)