;;;;;;;;;;;;;;;;;;; TEST CASES: M2 ;;;;;;;;;;;;;;;;
;;; The following is used by 'hw07-test-helpers.ss':
;;; Paste this into your solution-code for M2,
;;; and then have hw07-test-helpers.ss 'require' that file.

(define tests
  ; Each entry in the list is either
  ; [str val] (where val is the result of interpreting the string str), or
  ; [str val expr] (as above, but expr is the internal (struct) representation).
  `{; Some basic one-variable lets:
    ["let y be (3) in (7)" 7]
    ["let y be (3) in (y)" 3] 
    ["let y be (3) in ((y + y))" 6]
    ["let x be ((2 + 3)) in (x)" 5]
        
    ["let x be (5) in ((4 + 3))" 7]
    ["let x be (5) in ((x + 3))" 8]
    ;; Two variables, not shadowing:
    ["let y be (3) in (let x be (5) in ((x + y)))" 8]
    ["let y be (3) in (let x be (y) in ((x + y)))" 6]
    ;; Two variables, shadowing in the body:
    ["let x be (5) in (let x be (3) in (x))" 3]
    ["let x be (5) in (let x be (x) in (x))" 5]
    ["let x be (5) in (let x be ((x + 1)) in (x))" 6]
    ["let x be (5) in (let x be ((x + 1)) in (x + 2))" 8]
    ["let x be (5) in (let y be (3) in ((let x be (y) in ((x + y)) + x)))" 11]
    ["let y be (let z be (4) in (let y be (99) in (z))) in (let z be (5) in ((let z be (10) in (y) + (y + z))))" 13]
    
    ;; Check that we don't substitute Expr0:
    ["let x be (let x be (5) in (x)) in ((x + 4))" 9]
    ["let x be (let y be (5) in (y)) in ((x + 4))" 9]
    ["let x be (let x be (5) in ((x + 1))) in ((x + -4))" 2]
    ["let x be (let y be (5) in ((y + 1))) in ((x + -4))" 2]
    ["let x be (let x be (5) in (x)) in (x)" 5]
    ["let x be (let x be (5) in ((x + 1))) in (x)" 6]
    ["let x be (let y be (5) in ((y + 1))) in (x)" 6]        

    ;; These cases are *not* necessarily comprehensive.
    ;; To really understand what your code needs to do,
    ;; you'll have to work out some of these by hand,
    ;; and/or make your own test cases (make them complicated, 
    ;; but only complicated enough to do something interesting --
    ;; shadow a variable in one place, or shadow something from 2 levels above, or ...
    })