;;;; elisp-compiler.test --- Test the compiler for Elisp.  -*- scheme -*-
;;;;
;;;; Copyright (C) 2009, 2010 Free Software Foundation, Inc.
;;;; Daniel Kraft
;;;;
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
;;;; License as published by the Free Software Foundation; either
;;;; version 3 of the License, or (at your option) any later version.
;;;; 
;;;; This library is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;;;; Lesser General Public License for more details.
;;;; 
;;;; You should have received a copy of the GNU Lesser General Public
;;;; License along with this library; if not, write to the Free Software
;;;; Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

(define-module (test-elisp-compiler)
  :use-module (test-suite lib)
  :use-module (system base compile)
  :use-module (language elisp runtime))


; Macros to handle the compilation conveniently.

(define-syntax compile-test
  (syntax-rules (pass-if pass-if-equal pass-if-exception)
    ((_ (pass-if test-name exp))
     (pass-if test-name (compile 'exp #:from 'elisp #:to 'value)))
    ((_ (pass-if test-name exp #:opts opts))
     (pass-if test-name (compile 'exp #:from 'elisp #:to 'value #:opts opts)))
    ((_ (pass-if-equal test-name result exp))
     (pass-if test-name (equal? result
                                (compile 'exp #:from 'elisp #:to 'value))))
    ((_ (pass-if-exception test-name exc exp))
     (pass-if-exception test-name exc
                        (compile 'exp #:from 'elisp #:to 'value)))))

(define-syntax with-test-prefix/compile
  (syntax-rules ()
    ((_ section-name exp ...)
     (with-test-prefix section-name (compile-test exp) ...))))


; Test control structures.
; ========================

(with-test-prefix/compile "Sequencing"
  
  (pass-if-equal "progn" 1
    (progn (setq a 0)
           (setq a (1+ a))
           a))

  (pass-if "prog1"
    (progn (setq a 0)
           (setq b (prog1 a (setq a (1+ a))))
           (and (= a 1) (= b 0))))

  (pass-if "prog2"
    (progn (setq a 0)
           (setq b (prog2 (setq a (1+ a))
                          (setq a (1+ a))
                          (setq a (1+ a))))
           (and (= a 3) (= b 2)))))

(with-test-prefix/compile "Conditionals"

  (pass-if-equal "succeeding if" 1
    (if t 1 2))
  (pass-if "failing if"
    (and (= (if nil
              1
              (setq a 2) (setq a (1+ a)) a)
            3)
         (equal (if nil 1) nil)))

  (pass-if-equal "failing when" nil-value
    (when nil 1 2 3))
  (pass-if-equal "succeeding when" 42
    (progn (setq a 0)
           (when t (setq a 42) a)))

  (pass-if-equal "failing unless" nil-value
    (unless t 1 2 3))
  (pass-if-equal "succeeding unless" 42
    (progn (setq a 0)
           (unless nil (setq a 42) a)))

  (pass-if-equal "empty cond" nil-value
    (cond))
  (pass-if-equal "all failing cond" nil-value
    (cond (nil) (nil)))
  (pass-if-equal "only condition" 5
    (cond (nil) (5)))
  (pass-if-equal "succeeding cond value" 42
    (cond (nil) (t 42) (t 0)))
  (pass-if-equal "succeeding cond side-effect" 42
    (progn (setq a 0)
           (cond (nil) (t (setq a 42) 1) (t (setq a 0)))
           a)))

(with-test-prefix/compile "Combining Conditions"

  (pass-if-equal "empty and" t-value (and))
  (pass-if-equal "failing and" nil-value (and 1 2 nil 3))
  (pass-if-equal "succeeding and" 3 (and 1 2 3))

  (pass-if-equal "empty or" nil-value (or))
  (pass-if-equal "failing or" nil-value (or nil nil nil))
  (pass-if-equal "succeeding or" 1 (or nil 1 nil 2 nil 3))

  (pass-if-equal "not true" nil-value (not 1))
  (pass-if-equal "not false" t-value (not nil)))

(with-test-prefix/compile "Iteration"

  (pass-if-equal "failing while" 0
    (progn (setq a 0)
           (while nil (setq a 1))
           a))
  (pass-if-equal "running while" 120
    (progn (setq prod 1
                 i 1)
           (while (<= i 5)
             (setq prod (* i prod))
             (setq i (1+ i)))
           prod))

  (pass-if "dotimes"
    (progn (setq a 0)
           (setq count 100)
           (setq b (dotimes (i count)
                     (setq j (1+ i))
                     (setq a (+ a j))))
           (setq c (dotimes (i 10 42) nil))
           (and (= a 5050) (equal b nil) (= c 42))))

  (pass-if "dolist"
    (let ((mylist '(7 2 5)))
      (setq sum 0)
      (setq a (dolist (i mylist)
                (setq sum (+ sum i))))
      (setq b (dolist (i mylist 5) 0))
      (and (= sum (+ 7 2 5))
           (equal a nil)
           (equal mylist '(7 2 5))
           (equal b 5)))))

(with-test-prefix/compile "Exceptions"

  (pass-if "catch without exception"
    (and (setq a 0)
         (= (catch 'foobar
                   (setq a (1+ a))
                   (setq a (1+ a))
                   a)
            2)
         (= (catch (+ 1 2) a) 2)))

  ; FIXME: Figure out how to do this...
  ;(pass-if-exception "uncaught exception" 'elisp-exception
  ;  (throw 'abc 1))

  (pass-if "catch and throw"
    (and (setq mylist '(1 2))
         (= (catch 'abc (throw 'abc 2) 1) 2)
         (= (catch 'abc (catch 'def (throw 'abc (1+ 0)) 2) 3) 1)
         (= (catch 'abc (catch 'def (throw 'def 1) 2) 3) 3)
         (= (catch mylist (catch '(1 2) (throw mylist 1) 2) 3) 1)))

  (pass-if "unwind-protect"
    (progn (setq a 0 b 1 c 1)
           (catch 'exc
                  (unwind-protect (progn (setq a 1)
                                         (throw 'exc 0))
                                  (setq a 0)
                                  (setq b 0)))
           (unwind-protect nil (setq c 0))
           (and (= a 0) (= b 0) (= c 0)
                (= (unwind-protect 42 1 2 3) 42)))))

(with-test-prefix/compile "Eval"

  (pass-if-equal "basic eval" 3
    (progn (setq code '(+ 1 2))
           (eval code)))

  (pass-if "real dynamic code"
    (and (setq a 1 b 1 c 1)
         (defun set-code (var val)
           (list 'setq var val))
         (= a 1) (= b 1) (= c 1)
         (eval (set-code 'a '(+ 2 3)))
         (eval (set-code 'c 42))
         (= a 5) (= b 1) (= c 42)))

  ; Build code that recursively again and again calls eval.  What we want is
  ; something like:
  ; (eval '(1+ (eval '(1+ (eval 1)))))
  (pass-if "recursive eval"
    (progn (setq depth 10 i depth)
           (setq code '(eval 0))
           (while (not (zerop i))
             (setq code (#{`}# (eval (quote (1+ (#{,}# code))))))
             (setq i (1- i)))
           (= (eval code) depth))))


; Test handling of variables.
; ===========================

(with-test-prefix/compile "Variable Setting/Referencing"

  ; TODO: Check for variable-void error

  (pass-if-equal "setq and reference" 6
    (progn (setq a 1 b 2 c 3)
           (+ a b c)))
  (pass-if-equal "setq evaluation order" 1
    (progn (setq a 0 b 0)
           (setq a 1 b a)))
  (pass-if-equal "setq value" 2
    (progn (setq a 1 b 2)))

  (pass-if "set and symbol-value"
    (progn (setq myvar 'a)
           (and (= (set myvar 42) 42)
                (= a 42)
                (= (symbol-value myvar) 42))))
  (pass-if "void variables"
    (progn (setq a 1 b 2)
           (and (eq (makunbound 'b) 'b)
                (boundp 'a)
                (not (boundp 'b))))))

(with-test-prefix/compile "Let and Let*"

  (pass-if-equal "let without value" nil-value
    (let (a (b 5)) a))
  (pass-if-equal "basic let" 0
    (progn (setq a 0)
           (let ((a 1)
                 (b a))
             b)))

  (pass-if "let*"
    (progn (setq a 0)
           (and (let* ((a 1)
                       (b a))
                  (= b 1))
                (let* (a b)
                  (setq a 1 b 2)
                  (and (= a 1) (= b 2)))
                (= a 0)
                (not (boundp 'b)))))

  (pass-if "local scope"
    (progn (setq a 0)
           (setq b (let (a)
                     (setq a 1)
                     a))
           (and (= a 0)
                (= b 1)))))

(with-test-prefix/compile "Lexical Scoping"

  (pass-if "basic let semantics"
    (and (setq a 1)
         (lexical-let ((a 2) (b a))
           (and (= a 2) (= b 1)))
         (lexical-let* ((a 2) (b a))
           (and (= a 2) (= b 2) (setq a 42) (= a 42)))
         (= a 1)))

  (pass-if "lexical scope with lexical-let's"
    (and (setq a 1)
         (defun dyna () a)
         (lexical-let (a)
           (setq a 2)
           (and (= a 2) (= (dyna) 1)))
         (= a 1)
         (lexical-let* (a)
           (setq a 2)
           (and (= a 2) (= (dyna) 1)))
         (= a 1)))

  (pass-if "lexical scoping vs. symbol-value / set"
    (and (setq a 1)
         (lexical-let ((a 2))
           (and (= a 2)
                (= (symbol-value 'a) 1)
                (set 'a 3)
                (= a 2)
                (= (symbol-value 'a) 3)))
         (= a 3)))

  (pass-if "let inside lexical-let"
    (and (setq a 1 b 1)
         (defun dynvals () (cons a b))
         (lexical-let ((a 2))
           (and (= a 2) (equal (dynvals) '(1 . 1))
                (let ((a 3) (b a))
                  (and (= a 3) (= b 2)
                       (equal (dynvals) '(1 . 2))))
                (let* ((a 4) (b a))
                  (and (= a 4) (= b 4)
                       (equal (dynvals) '(1 . 4))))
                (= a 2)))
         (= a 1)))

  (pass-if "lambda args inside lexical-let"
    (and (setq a 1)
         (defun dyna () a)
         (lexical-let ((a 2) (b 42))
           (and (= a 2) (= (dyna) 1)
                ((lambda (a) (and (= a 3) (= b 42) (= (dyna) 3))) 3)
                ((lambda () (let ((a 3))
                              (and (= a 3) (= (dyna) 1)))))
                (= a 2) (= (dyna) 1)))
         (= a 1)))

  (pass-if "closures"
    (and (defun make-counter ()
           (lexical-let ((cnt 0))
             (lambda ()
               (setq cnt (1+ cnt)))))
         (setq c1 (make-counter) c2 (make-counter))
         (= (funcall c1) 1)
         (= (funcall c1) 2)
         (= (funcall c1) 3)
         (= (funcall c2) 1)
         (= (funcall c2) 2)
         (= (funcall c1) 4)
         (= (funcall c2) 3)))

  (pass-if "always lexical option (all)"
    (progn (setq a 0)
           (defun dyna () a)
           (let ((a 1))
             (and (= a 1) (= (dyna) 0))))
    #:opts '(#:always-lexical all))
  (pass-if "always lexical option (list)"
    (progn (setq a 0 b 0)
           (defun dyna () a)
           (defun dynb () b)
           (let ((a 1)
                 (b 1))
             (and (= a 1) (= (dyna) 0)
                  (= b 1) (= (dynb) 1))))
    #:opts '(#:always-lexical (a)))
  (pass-if "with-always-lexical"
    (progn (setq a 0)
           (defun dyna () a)
           (with-always-lexical (a)
             (let ((a 1))
               (and (= a 1) (= (dyna) 0))))))

  (pass-if "lexical lambda args"
    (progn (setq a 1 b 1)
           (defun dyna () a)
           (defun dynb () b)
           (with-always-lexical (a c)
             ((lambda (a b &optional c)
                (and (= a 3) (= (dyna) 1)
                     (= b 2) (= (dynb) 2)
                     (= c 1)))
              3 2 1))))

  ; Check if a lambda without dynamically bound arguments
  ; is tail-optimized by doing a deep recursion that would otherwise overflow
  ; the stack.
  (pass-if "lexical lambda tail-recursion"
    (with-always-lexical (i)
      (setq to 1000000)
      (defun iteration-1 (i)
        (if (< i to)
          (iteration-1 (1+ i))))
      (iteration-1 0)
      (setq x 0)
      (defun iteration-2 ()
        (if (< x to)
          (setq x (1+ x))
          (iteration-2)))
      (iteration-2)
      t)))


(with-test-prefix/compile "defconst and defvar"

  (pass-if-equal "defconst without docstring" 3.141
    (progn (setq pi 3)
           (defconst pi 3.141)
           pi))
  (pass-if-equal "defconst value" 'pi
    (defconst pi 3.141 "Pi"))

  (pass-if-equal "defvar without value" 42
    (progn (setq a 42)
           (defvar a)
           a))
  (pass-if-equal "defvar on already defined variable" 42
    (progn (setq a 42)
           (defvar a 1 "Some docstring is also ok")
           a))
  (pass-if-equal "defvar on undefined variable" 1
    (progn (makunbound 'a)
           (defvar a 1)
           a))
  (pass-if-equal "defvar value" 'a
    (defvar a)))


; Functions and lambda expressions.
; =================================

(with-test-prefix/compile "Lambda Expressions"

  (pass-if-equal "required arguments" 3
    ((lambda (a b c) c) 1 2 3))

  (pass-if-equal "optional argument" 3
    ((function (lambda (a &optional b c) c)) 1 2 3))
  (pass-if-equal "optional missing" nil-value
    ((lambda (&optional a) a)))

  (pass-if-equal "rest argument" '(3 4 5)
    ((lambda (a b &rest c) c) 1 2 3 4 5))
  (pass-if-equal "rest missing" nil-value
    ((lambda (a b &rest c) c) 1 2)))

(with-test-prefix/compile "Function Definitions"

  (pass-if-equal "defun" 3
    (progn (defun test (a b) (+ a b))
           (test 1 2)))
  (pass-if-equal "defun value" 'test
    (defun test (a b) (+ a b)))

  (pass-if "fset and symbol-function"
    (progn (setq myfunc 'x x 5)
           (and (= (fset myfunc 42) 42)
                (= (symbol-function myfunc) 42)
                (= x 5))))
  (pass-if "void function values"
    (progn (setq a 1)
           (defun test (a b) (+ a b))
           (fmakunbound 'a)
           (fset 'b 5)
           (and (fboundp 'b) (fboundp 'test)
                (not (fboundp 'a))
                (= a 1))))

  (pass-if "flet and flet*"
    (progn (defun foobar () 42)
           (defun test () (foobar))
           (and (= (test) 42)
                (flet ((foobar (lambda () 0))
                       (myfoo (symbol-function 'foobar)))
                  (and (= (myfoo) 42)
                       (= (test) 42)))
                (flet* ((foobar (lambda () 0))
                        (myfoo (symbol-function 'foobar)))
                  (= (myfoo) 42))
                (flet (foobar)
                  (defun foobar () 0)
                  (= (test) 42))
                (= (test) 42)))))

(with-test-prefix/compile "Calling Functions"

  (pass-if-equal "recursion" 120
    (progn (defun factorial (n prod)
             (if (zerop n)
               prod
               (factorial (1- n) (* prod n))))
           (factorial 5 1)))

  (pass-if "dynamic scoping"
    (progn (setq a 0)
           (defun foo ()
             (setq a (1+ a))
             a)
           (defun bar (a)
             (foo))
           (and (= 43 (bar 42))
                (zerop a))))

  (pass-if "funcall and apply argument handling"
    (and (defun allid (&rest args) args)
         (setq allid-var (symbol-function 'allid))
         (equal (funcall allid-var 1 2 3) '(1 2 3))
         (equal (funcall allid-var) nil)
         (equal (funcall allid-var 1 2 '(3 4)) '(1 2 (3 4)))
         (equal (funcall allid-var '()) '(()))
         (equal (apply allid-var 1 2 '(3 4)) '(1 2 3 4))
         (equal (apply allid-var '(1 2)) '(1 2))
         (equal (apply allid-var '()) nil)))

  (pass-if "raw functions with funcall"
    (and (= (funcall '+ 1 2) 3)
         (= (funcall (lambda (a b) (+ a b)) 1 2) 3)
         (= (funcall '(lambda (a b) (+ a b)) 1 2) 3))))


; Quoting and Backquotation.
; ==========================

(with-test-prefix/compile "Quotation"

  (pass-if "quote"
    (and (equal '42 42) (equal '"abc" "abc")
         (equal '(1 2 (3 (4) x)) '(1 2 (3 (4) x)))
         (not (equal '(1 2 (3 4 (x))) '(1 2 3 4 x)))
         (equal '(1 2 . 3) '(1 2 . 3))))

  (pass-if "simple backquote"
    (and (equal (#{`}# 42) 42)
         (equal (#{`}# (1 (a))) '(1 (a)))
         (equal (#{`}# (1 . 2)) '(1 . 2))))
  (pass-if "unquote"
    (progn (setq a 42 l '(18 12))
           (and (equal (#{`}# (#{,}# a)) 42)
                (equal (#{`}# (1 a ((#{,}# l)) . (#{,}# a))) '(1 a ((18 12)) . 42)))))
  (pass-if "unquote splicing"
    (progn (setq l '(18 12) empty '())
           (and (equal (#{`}# (#{,@}# l)) '(18 12))
                (equal (#{`}# (l 2 (3 (#{,@}# l)) ((#{,@}# l)) (#{,@}# l)))
                       '(l 2 (3 18 12) (18 12) 18 12))
                (equal (#{`}# (1 2 (#{,@}# empty) 3)) '(1 2 3))))))
      


; Macros.
; =======

(with-test-prefix/compile "Macros"

  (pass-if-equal "defmacro value" 'magic-number
    (defmacro magic-number () 42))

  (pass-if-equal "macro expansion" 1
    (progn (defmacro take-first (a b) a)
           (take-first 1 (/ 1 0)))))


; Test the built-ins.
; ===================

(with-test-prefix/compile "Equivalence Predicates"

  (pass-if "equal"
    (and (equal 2 2) (not (equal 1 2))
         (equal "abc" "abc") (not (equal "abc" "ABC"))
         (equal 'abc 'abc) (not (equal 'abc 'def))
         (equal '(1 2 (3 4) 5) '(1 2 (3 4) 5))
         (not (equal '(1 2 3 4 5) '(1 2 (3 4) 5)))))

  (pass-if "eq"
    (progn (setq some-list '(1 2))
           (setq some-string "abc")
           (and (eq 2 2) (not (eq 1 2))
                (eq 'abc 'abc) (not (eq 'abc 'def))
                (eq some-string some-string) (not (eq some-string "abc"))
                (eq some-list some-list) (not (eq some-list '(1 2)))))))

(with-test-prefix/compile "Number Built-Ins"

  (pass-if "floatp"
    (and (floatp 1.0) (not (floatp 1)) (not (floatp 'a))))
  (pass-if "integerp"
    (and (integerp 42) (integerp -2) (not (integerp 1.0))))
  (pass-if "numberp"
    (and (numberp 1.0) (numberp -2) (not (numberp 'a))))
  (pass-if "wholenump"
    (and (wholenump 0) (not (wholenump -2)) (not (wholenump 1.0))))
  (pass-if "zerop"
    (and (zerop 0) (zerop 0.0) (not (zerop 1))))

  (pass-if "comparisons"
    (and (= 1 1.0) (/= 0 1)
         (< 1 2) (> 2 1) (>= 1 1) (<= 1 1)
         (not (< 1 1)) (not (<= 2 1))))

  (pass-if "max and min"
    (and (= (max -5 2 4.0 1) 4.0) (= (min -5 2 4.0 1) -5)
         (= (max 1) 1) (= (min 1) 1)))
  (pass-if "abs"
    (and (= (abs 1.0) 1.0) (= (abs -5) 5)))

  (pass-if "float"
    (and (= (float 1) 1) (= (float 5.5) 5.5)
         (floatp (float 1))))

  (pass-if-equal "basic arithmetic operators" -8.5
    (+ (1+ 0) (1- 0) (- 5.5) (* 2 -2) (- 2 1)))
  (pass-if "modulo"
    (= (% 5 3) 2))

  (pass-if "floating point rounding"
    (and (= (ffloor 1.7) 1.0) (= (ffloor -1.2) -2.0) (= (ffloor 1.0) 1.0)
         (= (fceiling 1.2) 2.0) (= (fceiling -1.7) -1.0) (= (fceiling 1.0) 1.0)
         (= (ftruncate 1.6) 1.0) (= (ftruncate -1.7) -1.0)
         (= (fround 1.2) 1.0) (= (fround 1.7) 2.0) (= (fround -1.7) -2.0))))

(with-test-prefix/compile "List Built-Ins"

  (pass-if "consp and atomp"
    (and (consp '(1 2 3)) (consp '(1 2 . 3)) (consp '(a . b))
         (not (consp '())) (not (consp 1)) (not (consp "abc"))
         (atomp 'a) (atomp '()) (atomp -1.5) (atomp "abc")
         (not (atomp '(1 . 2))) (not (atomp '(1)))))
  (pass-if "listp and nlistp"
    (and (listp '(1 2 3)) (listp '(1)) (listp '()) (listp '(1 . 2))
         (not (listp 'a)) (not (listp 42)) (nlistp 42)
         (not (nlistp '())) (not (nlistp '(1 2 3))) (not (nlistp '(1 . 2)))))
  (pass-if "null"
    (and (null '()) (not (null 1)) (not (null '(1 2))) (not (null '(1 . 2)))))

  (pass-if "car and cdr"
    (and (equal (car '(1 2 3)) 1) (equal (cdr '(1 2 3)) '(2 3))
         (equal (car '()) nil) (equal (cdr '()) nil)
         (equal (car '(1 . 2)) 1) (equal (cdr '(1 . 2)) 2)
         (null (cdr '(1)))))
  (pass-if "car-safe and cdr-safe"
    (and (equal (car-safe '(1 2)) 1) (equal (cdr-safe '(1 2)) '(2))
         (equal (car-safe 5) nil) (equal (cdr-safe 5) nil)))

  (pass-if "pop"
    (progn (setq mylist '(a b c))
           (setq value (pop mylist))
           (and (equal value 'a)
                (equal mylist '(b c)))))
  (pass-if-equal "push" '(a b c)
    (progn (setq mylist '(b c))
           (push 'a mylist)))

  (pass-if "nth and nthcdr"
    (and (equal (nth -5 '(1 2 3)) 1) (equal (nth 3 '(1 2 3)) nil)
         (equal (nth 0 '(1 2 3)) 1) (equal (nth 2 '(1 2 3)) 3)
         (equal (nthcdr -5 '(1 2 3)) '(1 2 3))
         (equal (nthcdr 4 '(1 2 3)) nil)
         (equal (nthcdr 1 '(1 2 3)) '(2 3))
         (equal (nthcdr 2 '(1 2 3)) '(3))))

  (pass-if "length"
    (and (= (length '()) 0)
         (= (length '(1 2 3 4 5)) 5)
         (= (length '(1 2 (3 4 (5)) 6)) 4)))

  (pass-if "cons, list and make-list"
    (and (equal (cons 1 2) '(1 . 2)) (equal (cons 1 '(2 3)) '(1 2 3))
         (equal (cons 1 '()) '(1))
         (equal (list 'a) '(a)) (equal (list) '()) (equal (list 1 2) '(1 2))
         (equal (make-list 3 42) '(42 42 42))
         (equal (make-list 0 1) '())))
  (pass-if "append"
    (and (equal (append '(1 2) '(3 4) '(5)) '(1 2 3 4 5))
         (equal (append '(1 2) 3) '(1 2 . 3))))
  (pass-if "reverse"
    (and (equal (reverse '(5 4 3 2 1)) '(1 2 3 4 5))
         (equal (reverse '()) '())))
  (pass-if "copy-tree"
    (progn (setq mylist '(1 2 (3 4)))
           (and (not (eq mylist (copy-tree mylist)))
                (equal mylist (copy-tree mylist)))))

  (pass-if "number-sequence"
    (and (equal (number-sequence 5) '(5))
         (equal (number-sequence 5 9) '(5 6 7 8 9))
         (equal (number-sequence 5 9 3) '(5 8))
         (equal (number-sequence 5 1 -2) '(5 3 1))
         (equal (number-sequence 5 8 -1) '())
         (equal (number-sequence 5 1) '())
         (equal (number-sequence 5 5 0) '(5))))

  (pass-if "setcar and setcdr"
    (progn (setq pair '(1 . 2))
           (setq copy pair)
           (setq a (setcar copy 3))
           (setq b (setcdr copy 4))
           (and (= a 3) (= b 4)
                (equal pair '(3 . 4))))))