;;; fns-tests.el --- tests for src/fns.c  -*- lexical-binding:t -*-

;; Copyright (C) 2014-2021 Free Software Foundation, Inc.

;; This file is part of GNU Emacs.

;; This program is free software: you can redistribute it and/or
;; modify it under the terms of the GNU General Public License as
;; published by the Free Software Foundation, either version 3 of the
;; License, or (at your option) any later version.
;;
;; This program 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
;; General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see `https://www.gnu.org/licenses/'.

;;; Commentary:

;;; Code:

(require 'cl-lib)

;; Test that equality predicates work correctly on NaNs when combined
;; with hash tables based on those predicates.  This was not the case
;; for eql in Emacs 26.
(ert-deftest fns-tests-equality-nan ()
  (dolist (test (list #'eq #'eql #'equal))
    (let* ((h (make-hash-table :test test))
           (nan 0.0e+NaN)
           (-nan (- nan)))
      (puthash nan t h)
      (should (eq (funcall test nan -nan) (gethash -nan h))))))

(ert-deftest fns-tests-reverse ()
  (should-error (reverse))
  (should-error (reverse 1))
  (should-error (reverse (make-char-table 'foo)))
  (should (equal [] (reverse [])))
  (should (equal [0] (reverse [0])))
  (should (equal [1 2 3 4] (reverse (reverse [1 2 3 4]))))
  (should (equal '(a b c d) (reverse (reverse '(a b c d)))))
  (should (equal "xyzzy" (reverse (reverse "xyzzy"))))
  (should (equal "こんにちは / ｺﾝﾆﾁﾊ" (reverse (reverse "こんにちは / ｺﾝﾆﾁﾊ")))))

(ert-deftest fns-tests-nreverse ()
  (should-error (nreverse))
  (should-error (nreverse 1))
  (should-error (nreverse (make-char-table 'foo)))
  (should (equal (nreverse (copy-sequence "xyzzy")) "yzzyx"))
  (let ((A (vector)))
    (nreverse A)
    (should (equal A [])))
  (let ((A (vector 0)))
    (nreverse A)
    (should (equal A [0])))
  (let ((A (vector 1 2 3 4)))
    (nreverse A)
    (should (equal A [4 3 2 1])))
  (let ((A (vector 1 2 3 4)))
    (nreverse A)
    (nreverse A)
    (should (equal A [1 2 3 4])))
  (let* ((A (vector 1 2 3 4))
	 (B (nreverse (nreverse A))))
    (should (equal A B))))

(ert-deftest fns-tests-reverse-bool-vector ()
  (let ((A (make-bool-vector 10 nil)))
    (dotimes (i 5) (aset A i t))
    (should (equal [nil nil nil nil nil t t t t t] (vconcat (reverse A))))
    (should (equal A (reverse (reverse A))))))

(ert-deftest fns-tests-nreverse-bool-vector ()
  (let ((A (make-bool-vector 10 nil)))
    (dotimes (i 5) (aset A i t))
    (nreverse A)
    (should (equal [nil nil nil nil nil t t t t t] (vconcat A)))
    (should (equal [t t t t t nil nil nil nil nil] (vconcat (nreverse A))))))

(ert-deftest fns-tests-compare-strings ()
  (should-error (compare-strings))
  (should-error (compare-strings "xyzzy" "xyzzy"))
  (should (= (compare-strings "xyzzy" 0 10 "zyxxy" 0 5) -1))
  (should-error (compare-strings "xyzzy" 0 5 "zyxxy" -1 2))
  (should-error (compare-strings "xyzzy" 'foo nil "zyxxy" 0 1))
  (should-error (compare-strings "xyzzy" 0 'foo "zyxxy" 2 3))
  (should-error (compare-strings "xyzzy" 0 2 "zyxxy" 'foo 3))
  (should-error (compare-strings "xyzzy" nil 3 "zyxxy" 4 'foo))
  (should (eq (compare-strings "" nil nil "" nil nil) t))
  (should (eq (compare-strings "" 0 0 "" 0 0) t))
  (should (eq (compare-strings "test" nil nil "test" nil nil) t))
  (should (eq (compare-strings "test" nil nil "test" nil nil t) t))
  (should (eq (compare-strings "test" nil nil "test" nil nil nil) t))
  (should (eq (compare-strings "Test" nil nil "test" nil nil t) t))
  (should (= (compare-strings "Test" nil nil "test" nil nil) -1))
  (should (= (compare-strings "Test" nil nil "test" nil nil) -1))
  (should (= (compare-strings "test" nil nil "Test" nil nil) 1))
  (should (= (compare-strings "foobaz" nil nil "barbaz" nil nil) 1))
  (should (= (compare-strings "barbaz" nil nil "foobar" nil nil) -1))
  (should (= (compare-strings "foobaz" nil nil "farbaz" nil nil) 2))
  (should (= (compare-strings "farbaz" nil nil "foobar" nil nil) -2))
  (should (eq (compare-strings "abcxyz" 0 2 "abcprq" 0 2) t))
  (should (eq (compare-strings "abcxyz" 0 -3 "abcprq" 0 -3) t))
  (should (= (compare-strings "abcxyz" 0 6 "abcprq" 0 6) 4))
  (should (= (compare-strings "abcprq" 0 6 "abcxyz" 0 6) -4))
  (should (eq (compare-strings "xyzzy" -3 4 "azza" -3 3) t))
  (should (eq (compare-strings "こんにちはｺﾝﾆﾁﾊ" nil nil "こんにちはｺﾝﾆﾁﾊ" nil nil) t))
  (should (= (compare-strings "んにちはｺﾝﾆﾁﾊこ" nil nil "こんにちはｺﾝﾆﾁﾊ" nil nil) 1))
  (should (= (compare-strings "こんにちはｺﾝﾆﾁﾊ" nil nil "んにちはｺﾝﾆﾁﾊこ" nil nil) -1)))

(defun fns-tests--collate-enabled-p ()
  "Check whether collation functions are enabled."
  (and
   ;; When there is no collation library, collation functions fall back
   ;; to their lexicographic counterparts.  We don't need to test then.
   (not (ignore-errors (string-collate-equalp "" "" t)))
   ;; We use a locale, which might not be installed.  Check it.
   (ignore-errors
     (string-collate-equalp
      "" "" (if (eq system-type 'windows-nt) "enu_USA" "en_US.UTF-8")))))

(ert-deftest fns-tests-collate-strings ()
  (skip-unless (fns-tests--collate-enabled-p))

  (should (string-collate-equalp "xyzzy" "xyzzy"))
  (should-not (string-collate-equalp "xyzzy" "XYZZY"))

  ;; In POSIX or C locales, collation order is lexicographic.
  (should (string-collate-lessp "XYZZY" "xyzzy" "POSIX"))
  ;; In a language specific locale on MS-Windows, collation order is different.
  (when (eq system-type 'windows-nt)
    (should (string-collate-lessp "xyzzy" "XYZZY" "enu_USA")))

  ;; Ignore case.
  (should (string-collate-equalp "xyzzy" "XYZZY" nil t))

  ;; Locale must be valid.
  (should-error (string-collate-equalp "xyzzy" "xyzzy" "en_DE.UTF-8")))

;; There must be a check for valid codepoints.  (Check not implemented yet)
;  (should-error
;   (string-collate-equalp (string ?\x00110000) (string ?\x00110000)))
;; Invalid UTF-8 sequences shall be indicated.  How to create such strings?

(ert-deftest fns-tests-sort ()
  (should (equal (sort (list 9 5 2 -1 5 3 8 7 4) (lambda (x y) (< x y)))
		 '(-1 2 3 4 5 5 7 8 9)))
  (should (equal (sort (list 9 5 2 -1 5 3 8 7 4) (lambda (x y) (> x y)))
		 '(9 8 7 5 5 4 3 2 -1)))
  (should (equal (sort (vector 9 5 2 -1 5 3 8 7 4) (lambda (x y) (< x y)))
		 [-1 2 3 4 5 5 7 8 9]))
  (should (equal (sort (vector 9 5 2 -1 5 3 8 7 4) (lambda (x y) (> x y)))
		 [9 8 7 5 5 4 3 2 -1]))
  (should (equal
	   (sort
	    (vector
	     '(8 . "xxx") '(9 . "aaa") '(8 . "bbb") '(9 . "zzz")
	     '(9 . "ppp") '(8 . "ttt") '(8 . "eee") '(9 . "fff"))
	    (lambda (x y) (< (car x) (car y))))
	   [(8 . "xxx") (8 . "bbb") (8 . "ttt") (8 . "eee")
	    (9 . "aaa") (9 . "zzz") (9 . "ppp") (9 . "fff")]))
  ;; Bug#34104
  (should (equal (should-error (sort "cba" #'<) :type 'wrong-type-argument)
                 '(wrong-type-argument list-or-vector-p "cba"))))

(defvar w32-collate-ignore-punctuation)

(ert-deftest fns-tests-collate-sort ()
  (skip-unless (fns-tests--collate-enabled-p))

  ;; Punctuation and whitespace characters are relevant for POSIX.
  (should
   (equal
    (sort (list "11" "12" "1 1" "1 2" "1.1" "1.2")
	  (lambda (a b) (string-collate-lessp a b "POSIX")))
    '("1 1" "1 2" "1.1" "1.2" "11" "12")))
  ;; Punctuation and whitespace characters are not taken into account
  ;; for collation in other locales, on MS-Windows systems.
  (when (eq system-type 'windows-nt)
    (should
     (equal
      (sort (list "11" "12" "1 1" "1 2" "1.1" "1.2")
            (lambda (a b)
              (let ((w32-collate-ignore-punctuation t))
                (string-collate-lessp
                 a b "enu_USA"))))
      '("11" "1 1" "1.1" "12" "1 2" "1.2"))))

  ;; Diacritics are different letters for POSIX, they sort lexicographical.
  (should
   (equal
    (sort (list "Ævar" "Agustín" "Adrian" "Eli")
	  (lambda (a b) (string-collate-lessp a b "POSIX")))
    '("Adrian" "Agustín" "Eli" "Ævar")))
  ;; Diacritics are sorted between similar letters for other locales,
  ;; on MS-Windows systems.
  (when (eq system-type 'windows-nt)
    (should
     (equal
      (sort (list "Ævar" "Agustín" "Adrian" "Eli")
            (lambda (a b)
              (let ((w32-collate-ignore-punctuation t))
                (string-collate-lessp
                 a b "enu_USA"))))
      '("Adrian" "Ævar" "Agustín" "Eli")))))

(ert-deftest fns-tests-string-version-lessp ()
  (should (string-version-lessp "foo2.png" "foo12.png"))
  (should (not (string-version-lessp "foo12.png" "foo2.png")))
  (should (string-version-lessp "foo12.png" "foo20000.png"))
  (should (not (string-version-lessp "foo20000.png" "foo12.png")))
  (should (string-version-lessp "foo.png" "foo2.png"))
  (should (not (string-version-lessp "foo2.png" "foo.png")))
  (should (equal (sort (list "foo12.png" "foo2.png" "foo1.png")
                       'string-version-lessp)
                 '("foo1.png" "foo2.png" "foo12.png")))
  (should (string-version-lessp "foo2" "foo1234"))
  (should (not (string-version-lessp "foo1234" "foo2")))
  (should (string-version-lessp "foo.png" "foo2"))
  (should (string-version-lessp "foo1.25.5.png" "foo1.125.5"))
  (should (string-version-lessp "2" "1245"))
  (should (not (string-version-lessp "1245" "2"))))

(ert-deftest fns-tests-func-arity ()
  (should (equal (func-arity 'car) '(1 . 1)))
  (should (equal (func-arity 'caar) '(1 . 1)))
  (should (equal (func-arity 'format) '(1 . many)))
  (require 'info)
  (should (equal (func-arity 'Info-goto-node) '(1 . 3)))
  (should (equal (func-arity (lambda (&rest _x))) '(0 . many)))
  (should (equal (func-arity (eval '(lambda (_x &optional y)) nil)) '(1 . 2)))
  (should (equal (func-arity (eval '(lambda (_x &optional y)) t)) '(1 . 2)))
  (should (equal (func-arity 'let) '(1 . unevalled))))

(defun fns-tests--string-repeat (s o)
  (apply 'concat (make-list o s)))

(defmacro fns-tests--with-region (funcname string &rest args)
  "Apply FUNCNAME in a temp buffer on the region produced by STRING."
  (declare (indent 1))
  `(with-temp-buffer
     (insert ,string)
     (,funcname (point-min) (point-max) ,@args)
     (buffer-string)))

(ert-deftest fns-tests-base64-encode-region ()
  ;; standard variant RFC2045
  (should (equal (fns-tests--with-region base64-encode-region "") ""))
  (should (equal (fns-tests--with-region base64-encode-region "f") "Zg=="))
  (should (equal (fns-tests--with-region base64-encode-region "fo") "Zm8="))
  (should (equal (fns-tests--with-region base64-encode-region "foo") "Zm9v"))
  (should (equal (fns-tests--with-region base64-encode-region "foob") "Zm9vYg=="))
  (should (equal (fns-tests--with-region base64-encode-region "fooba") "Zm9vYmE="))
  (should (equal (fns-tests--with-region base64-encode-region "foobar") "Zm9vYmFy"))
  (should (equal (fns-tests--with-region base64-encode-region "\x14\xfb\x9c\x03\xd9\x7e") "FPucA9l+"))
  (should (equal (fns-tests--with-region base64-encode-region "\x14\xfb\x9c\x03\xd9\x7f") "FPucA9l/")))

(ert-deftest fns-tests-base64-encode-string ()
  ;; standard variant RFC2045
  (should (equal (base64-encode-string "") ""))
  (should (equal (base64-encode-string "f") "Zg=="))
  (should (equal (base64-encode-string "fo") "Zm8="))
  (should (equal (base64-encode-string "foo") "Zm9v"))
  (should (equal (base64-encode-string "foob") "Zm9vYg=="))
  (should (equal (base64-encode-string "fooba") "Zm9vYmE="))
  (should (equal (base64-encode-string "foobar") "Zm9vYmFy"))
  (should (equal (base64-encode-string "\x14\xfb\x9c\x03\xd9\x7e") "FPucA9l+"))
  (should (equal (base64-encode-string "\x14\xfb\x9c\x03\xd9\x7f") "FPucA9l/")))

(ert-deftest fns-test-base64url-encode-region ()
  ;; url variant with padding
  (should (equal (fns-tests--with-region base64url-encode-region "") ""))
  (should (equal (fns-tests--with-region base64url-encode-region "f") "Zg=="))
  (should (equal (fns-tests--with-region base64url-encode-region "fo") "Zm8="))
  (should (equal (fns-tests--with-region base64url-encode-region "foo") "Zm9v"))
  (should (equal (fns-tests--with-region base64url-encode-region "foob") "Zm9vYg=="))
  (should (equal (fns-tests--with-region base64url-encode-region "fooba") "Zm9vYmE="))
  (should (equal (fns-tests--with-region base64url-encode-region "foobar") "Zm9vYmFy"))
  (should (equal (fns-tests--with-region base64url-encode-region "\x14\xfb\x9c\x03\xd9\x7e") "FPucA9l-"))
  (should (equal (fns-tests--with-region base64url-encode-region "\x14\xfb\x9c\x03\xd9\x7f") "FPucA9l_"))

  ;; url variant no padding
  (should (equal (fns-tests--with-region base64url-encode-region "" t) ""))
  (should (equal (fns-tests--with-region base64url-encode-region "f" t) "Zg"))
  (should (equal (fns-tests--with-region base64url-encode-region "fo" t) "Zm8"))
  (should (equal (fns-tests--with-region base64url-encode-region "foo" t) "Zm9v"))
  (should (equal (fns-tests--with-region base64url-encode-region "foob" t) "Zm9vYg"))
  (should (equal (fns-tests--with-region base64url-encode-region "fooba" t) "Zm9vYmE"))
  (should (equal (fns-tests--with-region base64url-encode-region "foobar" t) "Zm9vYmFy"))
  (should (equal (fns-tests--with-region base64url-encode-region "\x14\xfb\x9c\x03\xd9\x7e" t) "FPucA9l-"))
  (should (equal (fns-tests--with-region base64url-encode-region "\x14\xfb\x9c\x03\xd9\x7f" t) "FPucA9l_"))


  ;; url variant no line break no padding
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "f" 100) t)
                 (concat (fns-tests--string-repeat "Zm" 66) "Zg")))
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "fo" 50) t)
                 (concat (fns-tests--string-repeat "Zm9mb2Zv" 16) "Zm9mbw")))
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "foo" 25) t)
                 (fns-tests--string-repeat "Zm9v" 25)))
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "foob" 15) t)
                 (fns-tests--string-repeat "Zm9vYmZvb2Jmb29i" 5)))
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "fooba" 15) t)
                 (fns-tests--string-repeat "Zm9vYmFmb29iYWZvb2Jh" 5)))
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "foobar" 15) t)
                 (concat (fns-tests--string-repeat "Zm9vYmFyZm9vYmFy" 7) "Zm9vYmFy")))
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "\x14\xfb\x9c\x03\xd9\x7e" 10) t)
                 (fns-tests--string-repeat "FPucA9l-" 10)))
  (should (equal (fns-tests--with-region base64url-encode-region (fns-tests--string-repeat "\x14\xfb\x9c\x03\xd9\x7f" 10) t)
                 (fns-tests--string-repeat "FPucA9l_" 10))))

(ert-deftest fns-test-base64url-encode-string ()
  ;; url variant with padding
  (should (equal (base64url-encode-string "") ""))
  (should (equal (base64url-encode-string "f") "Zg=="))
  (should (equal (base64url-encode-string "fo") "Zm8="))
  (should (equal (base64url-encode-string "foo") "Zm9v"))
  (should (equal (base64url-encode-string "foob") "Zm9vYg=="))
  (should (equal (base64url-encode-string "fooba") "Zm9vYmE="))
  (should (equal (base64url-encode-string "foobar") "Zm9vYmFy"))
  (should (equal (base64url-encode-string "\x14\xfb\x9c\x03\xd9\x7e") "FPucA9l-"))
  (should (equal (base64url-encode-string "\x14\xfb\x9c\x03\xd9\x7f") "FPucA9l_"))

  ;; url variant no padding
  (should (equal (base64url-encode-string "" t) ""))
  (should (equal (base64url-encode-string "f" t) "Zg"))
  (should (equal (base64url-encode-string "fo" t) "Zm8"))
  (should (equal (base64url-encode-string "foo" t) "Zm9v"))
  (should (equal (base64url-encode-string "foob" t) "Zm9vYg"))
  (should (equal (base64url-encode-string "fooba" t) "Zm9vYmE"))
  (should (equal (base64url-encode-string "foobar" t) "Zm9vYmFy"))
  (should (equal (base64url-encode-string "\x14\xfb\x9c\x03\xd9\x7e" t) "FPucA9l-"))
  (should (equal (base64url-encode-string "\x14\xfb\x9c\x03\xd9\x7f" t) "FPucA9l_"))


  ;; url variant no line break no padding
  (should (equal (base64url-encode-string (fns-tests--string-repeat "f" 100) t) (concat (fns-tests--string-repeat "Zm" 66) "Zg")))
  (should (equal (base64url-encode-string (fns-tests--string-repeat "fo" 50) t) (concat (fns-tests--string-repeat "Zm9mb2Zv" 16) "Zm9mbw")))
  (should (equal (base64url-encode-string (fns-tests--string-repeat "foo" 25) t) (fns-tests--string-repeat "Zm9v" 25)))
  (should (equal (base64url-encode-string (fns-tests--string-repeat "foob" 15) t) (fns-tests--string-repeat "Zm9vYmZvb2Jmb29i" 5)))
  (should (equal (base64url-encode-string (fns-tests--string-repeat "fooba" 15) t) (fns-tests--string-repeat "Zm9vYmFmb29iYWZvb2Jh" 5)))
  (should (equal (base64url-encode-string (fns-tests--string-repeat "foobar" 15) t) (concat (fns-tests--string-repeat "Zm9vYmFyZm9vYmFy" 7) "Zm9vYmFy")))
  (should (equal (base64url-encode-string (fns-tests--string-repeat "\x14\xfb\x9c\x03\xd9\x7e" 10) t) (fns-tests--string-repeat "FPucA9l-" 10)))
  (should (equal (base64url-encode-string (fns-tests--string-repeat "\x14\xfb\x9c\x03\xd9\x7f" 10) t) (fns-tests--string-repeat "FPucA9l_" 10))))

(ert-deftest fns-tests-base64-decode-string ()
  ;; standard variant RFC2045
  (should (equal (base64-decode-string "") ""))
  (should (equal (base64-decode-string "Zg==") "f"))
  (should (equal (base64-decode-string "Zm8=") "fo"))
  (should (equal (base64-decode-string "Zm9v") "foo"))
  (should (equal (base64-decode-string "Zm9vYg==") "foob"))
  (should (equal (base64-decode-string "Zm9vYmE=") "fooba"))
  (should (equal (base64-decode-string "Zm9vYmFy") "foobar"))
  (should (equal (base64-decode-string "FPucA9l+") "\x14\xfb\x9c\x03\xd9\x7e"))
  (should (equal (base64-decode-string "FPucA9l/") "\x14\xfb\x9c\x03\xd9\x7f"))

  ;; no padding
  (should (equal (base64-decode-string "" t) ""))
  (should (equal (base64-decode-string "Zg" t) "f"))
  (should (equal (base64-decode-string "Zm8" t) "fo"))
  (should (equal (base64-decode-string "Zm9v" t) "foo"))
  (should (equal (base64-decode-string "Zm9vYg" t) "foob"))
  (should (equal (base64-decode-string "Zm9vYmE" t) "fooba"))
  (should (equal (base64-decode-string "Zm9vYmFy" t) "foobar"))

  ;; url variant with padding
  (should (equal (base64-decode-string "") ""))
  (should (equal (base64-decode-string "Zg==" t) "f") )
  (should (equal (base64-decode-string "Zm8=" t) "fo"))
  (should (equal (base64-decode-string "Zm9v" t) "foo"))
  (should (equal (base64-decode-string "Zm9vYg==" t) "foob"))
  (should (equal (base64-decode-string "Zm9vYmE=" t) "fooba"))
  (should (equal (base64-decode-string "Zm9vYmFy" t) "foobar"))
  (should (equal (base64-decode-string "FPucA9l-" t) "\x14\xfb\x9c\x03\xd9\x7e"))
  (should (equal (base64-decode-string "FPucA9l_" t) "\x14\xfb\x9c\x03\xd9\x7f"))

  ;; url variant no padding
  (should (equal (base64-decode-string "") ""))
  (should (equal (base64-decode-string "Zg" t) "f"))
  (should (equal (base64-decode-string "Zm8" t) "fo"))
  (should (equal (base64-decode-string "Zm9v" t) "foo"))
  (should (equal (base64-decode-string "Zm9vYg" t) "foob"))
  (should (equal (base64-decode-string "Zm9vYmE" t) "fooba"))
  (should (equal (base64-decode-string "Zm9vYmFy" t) "foobar"))
  (should (equal (base64-decode-string "FPucA9l-" t) "\x14\xfb\x9c\x03\xd9\x7e"))
  (should (equal (base64-decode-string "FPucA9l_" t) "\x14\xfb\x9c\x03\xd9\x7f"))


  ;; url variant no line break no padding
  (should (equal (base64-decode-string (concat (fns-tests--string-repeat "Zm" 66) "Zg") t)
                 (fns-tests--string-repeat "f" 100)))
  (should (equal (base64-decode-string (concat (fns-tests--string-repeat "Zm9mb2Zv" 16) "Zm9mbw") t)
                 (fns-tests--string-repeat "fo" 50)))
  (should (equal (base64-decode-string (fns-tests--string-repeat "Zm9v" 25) t)
                 (fns-tests--string-repeat "foo" 25)))
  (should (equal (base64-decode-string (fns-tests--string-repeat "Zm9vYmZvb2Jmb29i" 5) t)
                 (fns-tests--string-repeat "foob" 15)))
  (should (equal (base64-decode-string (fns-tests--string-repeat "Zm9vYmFmb29iYWZvb2Jh" 5) t)
                 (fns-tests--string-repeat "fooba" 15)))
  (should (equal (base64-decode-string (concat (fns-tests--string-repeat "Zm9vYmFyZm9vYmFy" 7) "Zm9vYmFy") t)
                 (fns-tests--string-repeat "foobar" 15)))
  (should (equal (base64-decode-string (fns-tests--string-repeat "FPucA9l-" 10) t)
                 (fns-tests--string-repeat "\x14\xfb\x9c\x03\xd9\x7e" 10)))
  (should (equal (base64-decode-string (fns-tests--string-repeat "FPucA9l_" 10) t)
                 (fns-tests--string-repeat "\x14\xfb\x9c\x03\xd9\x7f" 10)))

  ;; errors check
  (should (eq :got-error (condition-case () (base64-decode-string "Zg=") (error :got-error))))
  (should (eq :got-error (condition-case () (base64-decode-string "Zm9vYmE") (error :got-error))))
  (should (eq :got-error (condition-case () (base64-decode-string "Zm9vYmFy=") (error :got-error))))
  (should (eq :got-error (condition-case () (base64-decode-string "Zg=Zg=") (error :got-error)))))

(ert-deftest fns-tests-hash-buffer ()
  (should (equal (sha1 "foo") "0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33"))
  (should (equal (with-temp-buffer
                   (insert "foo")
                   (buffer-hash))
                 (sha1 "foo")))
  ;; This tests whether the presence of a gap in the middle of the
  ;; buffer is handled correctly.
  (should (equal (with-temp-buffer
                   (insert "foo")
                   (goto-char 2)
                   (insert " ")
                   (backward-delete-char 1)
                   (buffer-hash))
                 (sha1 "foo"))))

(ert-deftest fns-tests-mapcan ()
  (should-error (mapcan))
  (should-error (mapcan #'identity))
  (should-error (mapcan #'identity (make-char-table 'foo)))
  (should (equal (mapcan #'list (list 1 2 3)) '(1 2 3)))
  ;; `mapcan' is destructive
  (let ((data (list (list 'foo) (list 'bar))))
    (should (equal (mapcan #'identity data) '(foo bar)))
    (should (equal data                     '((foo bar) (bar))))))

;; Test handling of cyclic and dotted lists.

(defun cyc1 (a)
  (let ((ls (make-list 10 a)))
    (nconc ls ls)
    ls))

(defun cyc2 (a b)
  (let ((ls1 (make-list 10 a))
        (ls2 (make-list 1000 b)))
    (nconc ls2 ls2)
    (nconc ls1 ls2)
    ls1))

(defun dot1 (a)
  (let ((ls (make-list 10 a)))
    (nconc ls 'tail)
    ls))

(defun dot2 (a b)
  (let ((ls1 (make-list 10 a))
        (ls2 (make-list 10 b)))
    (nconc ls1 ls2)
    (nconc ls2 'tail)
    ls1))

(ert-deftest test-cycle-length ()
  (should-error (length (cyc1 1)) :type 'circular-list)
  (should-error (length (cyc2 1 2)) :type 'circular-list)
  (should-error (length (dot1 1)) :type 'wrong-type-argument)
  (should-error (length (dot2 1 2)) :type 'wrong-type-argument))

(ert-deftest test-cycle-safe-length ()
  (should (<= 10 (safe-length (cyc1 1))))
  (should (<= 1010 (safe-length (cyc2 1 2))))
  (should (= 10 (safe-length (dot1 1))))
  (should (= 20 (safe-length (dot2 1 2)))))

(ert-deftest test-cycle-member ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (member 1 c1))
    (should (member 1 c2))
    (should (member 1 d1))
    (should (member 1 d2))
    (should-error (member 2 c1) :type 'circular-list)
    (should (member 2 c2))
    (should-error (member 2 d1) :type 'wrong-type-argument)
    (should (member 2 d2))
    (should-error (member 3 c1) :type 'circular-list)
    (should-error (member 3 c2) :type 'circular-list)
    (should-error (member 3 d1) :type 'wrong-type-argument)
    (should-error (member 3 d2) :type 'wrong-type-argument)))

(ert-deftest test-cycle-memq ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (memq 1 c1))
    (should (memq 1 c2))
    (should (memq 1 d1))
    (should (memq 1 d2))
    (should-error (memq 2 c1) :type 'circular-list)
    (should (memq 2 c2))
    (should-error (memq 2 d1) :type 'wrong-type-argument)
    (should (memq 2 d2))
    (should-error (memq 3 c1) :type 'circular-list)
    (should-error (memq 3 c2) :type 'circular-list)
    (should-error (memq 3 d1) :type 'wrong-type-argument)
    (should-error (memq 3 d2) :type 'wrong-type-argument)))

(ert-deftest test-cycle-memql ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (memql 1 c1))
    (should (memql 1 c2))
    (should (memql 1 d1))
    (should (memql 1 d2))
    (should-error (memql 2 c1) :type 'circular-list)
    (should (memql 2 c2))
    (should-error (memql 2 d1) :type 'wrong-type-argument)
    (should (memql 2 d2))
    (should-error (memql 3 c1) :type 'circular-list)
    (should-error (memql 3 c2) :type 'circular-list)
    (should-error (memql 3 d1) :type 'wrong-type-argument)
    (should-error (memql 3 d2) :type 'wrong-type-argument)))

(ert-deftest test-cycle-assq ()
  (let ((c1 (cyc1 '(1)))
        (c2 (cyc2 '(1) '(2)))
        (d1 (dot1 '(1)))
        (d2 (dot2 '(1) '(2))))
    (should (assq 1 c1))
    (should (assq 1 c2))
    (should (assq 1 d1))
    (should (assq 1 d2))
    (should-error (assq 2 c1) :type 'circular-list)
    (should (assq 2 c2))
    (should-error (assq 2 d1) :type 'wrong-type-argument)
    (should (assq 2 d2))
    (should-error (assq 3 c1) :type 'circular-list)
    (should-error (assq 3 c2) :type 'circular-list)
    (should-error (assq 3 d1) :type 'wrong-type-argument)
    (should-error (assq 3 d2) :type 'wrong-type-argument)))

(ert-deftest test-cycle-assoc ()
  (let ((c1 (cyc1 '(1)))
        (c2 (cyc2 '(1) '(2)))
        (d1 (dot1 '(1)))
        (d2 (dot2 '(1) '(2))))
    (should (assoc 1 c1))
    (should (assoc 1 c2))
    (should (assoc 1 d1))
    (should (assoc 1 d2))
    (should-error (assoc 2 c1) :type 'circular-list)
    (should (assoc 2 c2))
    (should-error (assoc 2 d1) :type 'wrong-type-argument)
    (should (assoc 2 d2))
    (should-error (assoc 3 c1) :type 'circular-list)
    (should-error (assoc 3 c2) :type 'circular-list)
    (should-error (assoc 3 d1) :type 'wrong-type-argument)
    (should-error (assoc 3 d2) :type 'wrong-type-argument)))

(ert-deftest test-assoc-testfn ()
  (let ((alist '(("a" . 1) ("b" . 2))))
    (should-not (assoc "a" alist #'ignore))
    (should (eq (assoc "b" alist #'string-equal) (cadr alist)))
    (should-not (assoc "b" alist #'eq))))

(ert-deftest test-cycle-rassq ()
  (let ((c1 (cyc1 '(0 . 1)))
        (c2 (cyc2 '(0 . 1) '(0 . 2)))
        (d1 (dot1 '(0 . 1)))
        (d2 (dot2 '(0 . 1) '(0 . 2))))
    (should (rassq 1 c1))
    (should (rassq 1 c2))
    (should (rassq 1 d1))
    (should (rassq 1 d2))
    (should-error (rassq 2 c1) :type 'circular-list)
    (should (rassq 2 c2))
    (should-error (rassq 2 d1) :type 'wrong-type-argument)
    (should (rassq 2 d2))
    (should-error (rassq 3 c1) :type 'circular-list)
    (should-error (rassq 3 c2) :type 'circular-list)
    (should-error (rassq 3 d1) :type 'wrong-type-argument)
    (should-error (rassq 3 d2) :type 'wrong-type-argument)))

(ert-deftest test-cycle-rassoc ()
  (let ((c1 (cyc1 '(0 . 1)))
        (c2 (cyc2 '(0 . 1) '(0 . 2)))
        (d1 (dot1 '(0 . 1)))
        (d2 (dot2 '(0 . 1) '(0 . 2))))
    (should (rassoc 1 c1))
    (should (rassoc 1 c2))
    (should (rassoc 1 d1))
    (should (rassoc 1 d2))
    (should-error (rassoc 2 c1) :type 'circular-list)
    (should (rassoc 2 c2))
    (should-error (rassoc 2 d1) :type 'wrong-type-argument)
    (should (rassoc 2 d2))
    (should-error (rassoc 3 c1) :type 'circular-list)
    (should-error (rassoc 3 c2) :type 'circular-list)
    (should-error (rassoc 3 d1) :type 'wrong-type-argument)
    (should-error (rassoc 3 d2) :type 'wrong-type-argument)))

(ert-deftest test-cycle-delq ()
  (should-error (delq 1 (cyc1 1)) :type 'circular-list)
  (should-error (delq 1 (cyc2 1 2)) :type 'circular-list)
  (should-error (delq 1 (dot1 1)) :type 'wrong-type-argument)
  (should-error (delq 1 (dot2 1 2)) :type 'wrong-type-argument)
  (should-error (delq 2 (cyc1 1)) :type 'circular-list)
  (should-error (delq 2 (cyc2 1 2)) :type 'circular-list)
  (should-error (delq 2 (dot1 1)) :type 'wrong-type-argument)
  (should-error (delq 2 (dot2 1 2)) :type 'wrong-type-argument)
  (should-error (delq 3 (cyc1 1)) :type 'circular-list)
  (should-error (delq 3 (cyc2 1 2)) :type 'circular-list)
  (should-error (delq 3 (dot1 1)) :type 'wrong-type-argument)
  (should-error (delq 3 (dot2 1 2)) :type 'wrong-type-argument))

(ert-deftest test-cycle-delete ()
  (should-error (delete 1 (cyc1 1)) :type 'circular-list)
  (should-error (delete 1 (cyc2 1 2)) :type 'circular-list)
  (should-error (delete 1 (dot1 1)) :type 'wrong-type-argument)
  (should-error (delete 1 (dot2 1 2)) :type 'wrong-type-argument)
  (should-error (delete 2 (cyc1 1)) :type 'circular-list)
  (should-error (delete 2 (cyc2 1 2)) :type 'circular-list)
  (should-error (delete 2 (dot1 1)) :type 'wrong-type-argument)
  (should-error (delete 2 (dot2 1 2)) :type 'wrong-type-argument)
  (should-error (delete 3 (cyc1 1)) :type 'circular-list)
  (should-error (delete 3 (cyc2 1 2)) :type 'circular-list)
  (should-error (delete 3 (dot1 1)) :type 'wrong-type-argument)
  (should-error (delete 3 (dot2 1 2)) :type 'wrong-type-argument))

(ert-deftest test-cycle-reverse ()
  (should-error (reverse (cyc1 1)) :type 'circular-list)
  (should-error (reverse (cyc2 1 2)) :type 'circular-list)
  (should-error (reverse (dot1 1)) :type 'wrong-type-argument)
  (should-error (reverse (dot2 1 2)) :type 'wrong-type-argument))

(ert-deftest test-cycle-plist-get ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (plist-get c1 1))
    (should (plist-get c2 1))
    (should (plist-get d1 1))
    (should (plist-get d2 1))
    (should-not (plist-get c1 2))
    (should (plist-get c2 2))
    (should-not (plist-get d1 2))
    (should (plist-get d2 2))
    (should-not (plist-get c1 3))
    (should-not (plist-get c2 3))
    (should-not (plist-get d1 3))
    (should-not (plist-get d2 3))))

(ert-deftest test-cycle-lax-plist-get ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (lax-plist-get c1 1))
    (should (lax-plist-get c2 1))
    (should (lax-plist-get d1 1))
    (should (lax-plist-get d2 1))
    (should-error (lax-plist-get c1 2) :type 'circular-list)
    (should (lax-plist-get c2 2))
    (should-error (lax-plist-get d1 2) :type 'wrong-type-argument)
    (should (lax-plist-get d2 2))
    (should-error (lax-plist-get c1 3) :type 'circular-list)
    (should-error (lax-plist-get c2 3) :type 'circular-list)
    (should-error (lax-plist-get d1 3) :type 'wrong-type-argument)
    (should-error (lax-plist-get d2 3) :type 'wrong-type-argument)))

(ert-deftest test-cycle-plist-member ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (plist-member c1 1))
    (should (plist-member c2 1))
    (should (plist-member d1 1))
    (should (plist-member d2 1))
    (should-error (plist-member c1 2) :type 'circular-list)
    (should (plist-member c2 2))
    (should-error (plist-member d1 2) :type 'wrong-type-argument)
    (should (plist-member d2 2))
    (should-error (plist-member c1 3) :type 'circular-list)
    (should-error (plist-member c2 3) :type 'circular-list)
    (should-error (plist-member d1 3) :type 'wrong-type-argument)
    (should-error (plist-member d2 3) :type 'wrong-type-argument)))

(ert-deftest test-cycle-plist-put ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (plist-put c1 1 1))
    (should (plist-put c2 1 1))
    (should (plist-put d1 1 1))
    (should (plist-put d2 1 1))
    (should-error (plist-put c1 2 2) :type 'circular-list)
    (should (plist-put c2 2 2))
    (should-error (plist-put d1 2 2) :type 'wrong-type-argument)
    (should (plist-put d2 2 2))
    (should-error (plist-put c1 3 3) :type 'circular-list)
    (should-error (plist-put c2 3 3) :type 'circular-list)
    (should-error (plist-put d1 3 3) :type 'wrong-type-argument)
    (should-error (plist-put d2 3 3) :type 'wrong-type-argument)))

(ert-deftest test-cycle-lax-plist-put ()
  (let ((c1 (cyc1 1))
        (c2 (cyc2 1 2))
        (d1 (dot1 1))
        (d2 (dot2 1 2)))
    (should (lax-plist-put c1 1 1))
    (should (lax-plist-put c2 1 1))
    (should (lax-plist-put d1 1 1))
    (should (lax-plist-put d2 1 1))
    (should-error (lax-plist-put c1 2 2) :type 'circular-list)
    (should (lax-plist-put c2 2 2))
    (should-error (lax-plist-put d1 2 2) :type 'wrong-type-argument)
    (should (lax-plist-put d2 2 2))
    (should-error (lax-plist-put c1 3 3) :type 'circular-list)
    (should-error (lax-plist-put c2 3 3) :type 'circular-list)
    (should-error (lax-plist-put d1 3 3) :type 'wrong-type-argument)
    (should-error (lax-plist-put d2 3 3) :type 'wrong-type-argument)))

(ert-deftest test-cycle-equal ()
  (should-error (equal (cyc1 1) (cyc1 1)))
  (should-error (equal (cyc2 1 2) (cyc2 1 2))))

(ert-deftest test-cycle-nconc ()
  (should-error (nconc (cyc1 1) 'tail) :type 'circular-list)
  (should-error (nconc (cyc2 1 2) 'tail) :type 'circular-list))

(ert-deftest plist-get/odd-number-of-elements ()
  "Test that `plist-get' doesn't signal an error on degenerate plists."
  (should-not (plist-get '(:foo 1 :bar) :bar)))

(ert-deftest lax-plist-get/odd-number-of-elements ()
  "Check for https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27726."
  (should (equal (should-error (lax-plist-get '(:foo 1 :bar) :bar)
                               :type 'wrong-type-argument)
                 '(wrong-type-argument plistp (:foo 1 :bar)))))

(ert-deftest plist-put/odd-number-of-elements ()
  "Check for https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27726."
  (should (equal (should-error (plist-put '(:foo 1 :bar) :zot 2)
                               :type 'wrong-type-argument)
                 '(wrong-type-argument plistp (:foo 1 :bar)))))

(ert-deftest lax-plist-put/odd-number-of-elements ()
  "Check for https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27726."
  (should (equal (should-error (lax-plist-put '(:foo 1 :bar) :zot 2)
                               :type 'wrong-type-argument)
                 '(wrong-type-argument plistp (:foo 1 :bar)))))

(ert-deftest plist-member/improper-list ()
  "Check for https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27726."
  (should (equal (should-error (plist-member '(:foo 1 . :bar) :qux)
                               :type 'wrong-type-argument)
                 '(wrong-type-argument plistp (:foo 1 . :bar)))))

(ert-deftest test-string-distance ()
  "Test `string-distance' behavior."
  ;; ASCII characters are always fine
  (should (equal 1 (string-distance "heelo" "hello")))
  (should (equal 2 (string-distance "aeelo" "hello")))
  (should (equal 0 (string-distance "ab" "ab" t)))
  (should (equal 1 (string-distance "ab" "abc" t)))

  ;; string containing hanzi character, compare by byte
  (should (equal 6 (string-distance "ab" "ab我她" t)))
  (should (equal 3 (string-distance "ab" "a我b" t)))
  (should (equal 3 (string-distance "我" "她" t)))

  ;; string containing hanzi character, compare by character
  (should (equal 2 (string-distance "ab" "ab我她")))
  (should (equal 1 (string-distance "ab" "a我b")))
  (should (equal 1 (string-distance "我" "她"))))

(ert-deftest test-bignum-eql ()
  "Test that `eql' works for bignums."
  (let ((x (+ most-positive-fixnum 1))
        (y (+ most-positive-fixnum 1)))
    (should (eq x x))
    (should (eql x y))
    (should (equal x y))
    (should-not (eql x 0.0e+NaN))
    (should (memql x (list y)))))

(ert-deftest test-bignum-hash ()
  "Test that hash tables work for bignums."
  ;; Make two bignums that are eql but not eq.
  (let ((b1 (1+ most-positive-fixnum))
        (b2 (1+ most-positive-fixnum)))
    (dolist (test '(eq eql equal))
      (let ((hash (make-hash-table :test test)))
        (puthash b1 t hash)
        (should (eq (gethash b2 hash)
                    (funcall test b1 b2)))))))

(ert-deftest test-nthcdr-simple ()
  (should (eq (nthcdr 0 'x) 'x))
  (should (eq (nthcdr 1 '(x . y)) 'y))
  (should (eq (nthcdr 2 '(x y . z)) 'z)))

(ert-deftest test-nthcdr-circular ()
  (dolist (len '(1 2 5 37 120 997 1024))
    (let ((cycle (make-list len nil)))
      (setcdr (last cycle) cycle)
      (dolist (n (list (1- most-negative-fixnum) most-negative-fixnum
                       -1 0 1
                       (1- len) len (1+ len)
                       most-positive-fixnum (1+ most-positive-fixnum)
                       (* 2 most-positive-fixnum)
                       (* most-positive-fixnum most-positive-fixnum)
                       (ash 1 12345)))
        (let ((a (nthcdr n cycle))
              (b (if (<= n 0) cycle (nthcdr (mod n len) cycle))))
          (should (equal (list (eq a b) n len)
                         (list t n len))))))))

(ert-deftest test-proper-list-p ()
  "Test `proper-list-p' behavior."
  (dotimes (length 4)
    ;; Proper and dotted lists.
    (let ((list (make-list length 0)))
      (should (= (proper-list-p list) length))
      (should (not (proper-list-p (nconc list 0)))))
    ;; Circular lists.
    (dotimes (n (1+ length))
      (let ((circle (make-list (1+ length) 0)))
        (should (not (proper-list-p (nconc circle (nthcdr n circle))))))))
  ;; Atoms.
  (should (not (proper-list-p 0)))
  (should (not (proper-list-p "")))
  (should (not (proper-list-p [])))
  (should (not (proper-list-p (make-bool-vector 0 nil))))
  (should (not (proper-list-p (make-symbol "a")))))

(ert-deftest test-hash-function-that-mutates-hash-table ()
  (define-hash-table-test 'badeq 'eq 'bad-hash)
  (let ((h (make-hash-table :test 'badeq :size 1 :rehash-size 1)))
    (defun bad-hash (k)
      (if (eq k 100)
	  (clrhash h))
      (sxhash-eq k))
    (should-error
     (dotimes (k 200)
       (puthash k k h)))
    (should (= 100 (hash-table-count h)))))

(ert-deftest test-sxhash-equal ()
  (should (= (sxhash-equal (* most-positive-fixnum most-negative-fixnum))
	     (sxhash-equal (* most-positive-fixnum most-negative-fixnum))))
  (should (= (sxhash-equal (make-string 1000 ?a))
	     (sxhash-equal (make-string 1000 ?a))))
  (should (= (sxhash-equal (point-marker))
	     (sxhash-equal (point-marker))))
  (should (= (sxhash-equal (make-vector 1000 (make-string 10 ?a)))
	     (sxhash-equal (make-vector 1000 (make-string 10 ?a)))))
  (should (= (sxhash-equal (make-bool-vector 1000 t))
	     (sxhash-equal (make-bool-vector 1000 t))))
  (should (= (sxhash-equal (make-char-table nil (make-string 10 ?a)))
	     (sxhash-equal (make-char-table nil (make-string 10 ?a)))))
  (should (= (sxhash-equal (record 'a (make-string 10 ?a)))
	     (sxhash-equal (record 'a (make-string 10 ?a))))))

(ert-deftest test-secure-hash ()
  (should (equal (secure-hash 'md5    "foobar")
                 "3858f62230ac3c915f300c664312c63f"))
  (should (equal (secure-hash 'sha1   "foobar")
                 "8843d7f92416211de9ebb963ff4ce28125932878"))
  (should (equal (secure-hash 'sha224 "foobar")
                 "de76c3e567fca9d246f5f8d3b2e704a38c3c5e258988ab525f941db8"))
  (should (equal (secure-hash 'sha256 "foobar")
                 (concat "c3ab8ff13720e8ad9047dd39466b3c89"
                         "74e592c2fa383d4a3960714caef0c4f2")))
  (should (equal (secure-hash 'sha384 "foobar")
                 (concat "3c9c30d9f665e74d515c842960d4a451c83a0125fd3de739"
                         "2d7b37231af10c72ea58aedfcdf89a5765bf902af93ecf06")))
  (should (equal (secure-hash 'sha512 "foobar")
                 (concat "0a50261ebd1a390fed2bf326f2673c145582a6342d5"
                         "23204973d0219337f81616a8069b012587cf5635f69"
                         "25f1b56c360230c19b273500ee013e030601bf2425")))
  ;; Test that a call to getrandom returns the right format.
  ;; This does not test randomness; it's merely a format check.
  (should (string-match "\\`[0-9a-f]\\{128\\}\\'"
                        (secure-hash 'sha512 'iv-auto 100))))

(ert-deftest test-vector-delete ()
  (let ((v1 (make-vector 1000 1)))
    (should (equal (delete t [nil t]) [nil]))
    (should (equal (delete 1 v1) (vector)))
    (should (equal (delete 2 v1) v1))))

(ert-deftest string-search ()
  (should (equal (string-search "zot" "foobarzot") 6))
  (should (equal (string-search "foo" "foobarzot") 0))
  (should (not (string-search "fooz" "foobarzot")))
  (should (not (string-search "zot" "foobarzo")))
  (should (equal (string-search "ab" "ab") 0))
  (should (equal (string-search "ab\0" "ab") nil))
  (should (equal (string-search "ab" "abababab" 3) 4))
  (should (equal (string-search "ab" "ababac" 3) nil))
  (should (equal (string-search "aaa" "aa") nil))
  (let ((case-fold-search t))
    (should (equal (string-search "ab" "AB") nil)))

  (should (equal
           (string-search (make-string 2 130)
	                  (concat "helló" (make-string 5 130 t) "bár"))
           5))
  (should (equal
           (string-search (make-string 2 127)
	                  (concat "helló" (make-string 5 127 t) "bár"))
           5))

  (should (equal (string-search "\377" "a\377ø") 1))
  (should (equal (string-search "\377" "a\377a") 1))

  (should (not (string-search (make-string 1 255) "a\377ø")))
  (should (not (string-search (make-string 1 255) "a\377a")))

  (should (equal (string-search "fóo" "zotfóo") 3))

  (should (equal (string-search (string-to-multibyte "\377") "ab\377c") 2))
  (should (equal (string-search "\303" "aøb") nil))
  (should (equal (string-search "\270" "aøb") nil))
  (should (equal (string-search "ø" "\303\270") nil))
  (should (equal (string-search "ø" (make-string 32 ?a)) nil))
  (should (equal (string-search "ø" (string-to-multibyte (make-string 32 ?a)))
                 nil))
  (should (equal (string-search "o" (string-to-multibyte
                                     (apply #'string
                                            (number-sequence ?a ?z))))
                 14))

  (should (equal (string-search "a\U00010f98z" "a\U00010f98a\U00010f98z") 2))

  (should-error (string-search "a" "abc" -1))
  (should-error (string-search "a" "abc" 4))
  (should-error (string-search "a" "abc" 100000000000))

  (should (equal (string-search "a" "aaa" 3) nil))
  (should (equal (string-search "aa" "aa" 1) nil))
  (should (equal (string-search "\0" "") nil))

  (should (equal (string-search "" "") 0))
  (should-error (string-search "" "" 1))
  (should (equal (string-search "" "abc") 0))
  (should (equal (string-search "" "abc" 2) 2))
  (should (equal (string-search "" "abc" 3) 3))
  (should-error (string-search "" "abc" 4))
  (should-error (string-search "" "abc" -1))

  (should-not (string-search "ø" "foo\303\270"))
  (should-not (string-search "\303\270" "ø"))
  (should-not (string-search "\370" "ø"))
  (should-not (string-search (string-to-multibyte "\370") "ø"))
  (should-not (string-search "ø" "\370"))
  (should-not (string-search "ø" (string-to-multibyte "\370")))
  (should-not (string-search "\303\270" "\370"))
  (should-not (string-search (string-to-multibyte "\303\270") "\370"))
  (should-not (string-search "\303\270" (string-to-multibyte "\370")))
  (should-not (string-search (string-to-multibyte "\303\270")
                             (string-to-multibyte "\370")))
  (should-not (string-search "\370" "\303\270"))
  (should-not (string-search (string-to-multibyte "\370") "\303\270"))
  (should-not (string-search "\370" (string-to-multibyte "\303\270")))
  (should-not (string-search (string-to-multibyte "\370")
                             (string-to-multibyte "\303\270")))
  (should (equal (string-search (string-to-multibyte "o\303\270") "foo\303\270")
                 2))
  (should (equal (string-search "\303\270" "foo\303\270") 3)))

(ert-deftest object-intervals ()
  (should (equal (object-intervals (propertize "foo" 'bar 'zot))
                 '((0 3 (bar zot)))))
  (should (equal (object-intervals (concat (propertize "foo" 'bar 'zot)
                                           (propertize "foo" 'gazonk "gazonk")))
                 '((0 3 (bar zot)) (3 6 (gazonk "gazonk")))))
  (should (equal
           (with-temp-buffer
             (insert "foobar")
             (put-text-property 1 3 'foo 1)
             (put-text-property 3 6 'bar 2)
             (put-text-property 2 5 'zot 3)
             (object-intervals (current-buffer)))
           '((0 1 (foo 1)) (1 2 (zot 3 foo 1)) (2 4 (zot 3 bar 2))
             (4 5 (bar 2)) (5 6 nil)))))

(ert-deftest length-equals-tests ()
  (should-not (length< (list 1 2 3) 2))
  (should-not (length< (list 1 2 3) 3))
  (should (length< (list 1 2 3) 4))

  (should-not (length< "abc" 2))
  (should-not (length< "abc" 3))
  (should (length< "abc" 4))

  (should (length> (list 1 2 3) 2))
  (should-not (length> (list 1 2 3) 3))
  (should-not (length> (list 1 2 3) 4))

  (should (length> "abc" 2))
  (should-not (length> "abc" 3))
  (should-not (length> "abc" 4))

  (should-not (length= (list 1 2 3) 2))
  (should (length= (list 1 2 3) 3))
  (should-not (length= (list 1 2 3) 4))

  (should-not (length= "abc" 2))
  (should (length= "abc" 3))
  (should-not (length= "abc" 4))

  (should-not (length< (list 1 2 3) -1))
  (should-not (length< (list 1 2 3) 0))
  (should-not (length< (list 1 2 3) -10))

  (should (length> (list 1 2 3) -1))
  (should (length> (list 1 2 3) 0))

  (should-not (length= (list 1 2 3) -1))
  (should-not (length= (list 1 2 3) 0))
  (should-not (length= (list 1 2 3) 1))

  (should-error
   (let ((list (list 1)))
     (setcdr list list)
     (length< list #x1fffe))))

(defun approx-equal (list1 list2)
  (and (equal (length list1) (length list2))
       (cl-loop for v1 in list1
                for v2 in list2
                when (not (or (= v1 v2)
                              (< (abs (- v1 v2)) 0.1)))
                return nil
                finally return t)))

(ert-deftest test-buffer-line-stats-nogap ()
  (with-temp-buffer
    (insert "")
    (should (approx-equal (buffer-line-statistics) '(0 0 0))))
  (with-temp-buffer
    (insert "123\n")
    (should (approx-equal (buffer-line-statistics) '(1 3 3))))
  (with-temp-buffer
    (insert "123\n12345\n123\n")
    (should (approx-equal (buffer-line-statistics) '(3 5 3.66))))
  (with-temp-buffer
    (insert "123\n12345\n123")
    (should (approx-equal (buffer-line-statistics) '(3 5 3.66))))
  (with-temp-buffer
    (insert "123\n12345")
    (should (approx-equal (buffer-line-statistics) '(2 5 4))))

  (with-temp-buffer
    (insert "123\n12é45\n123\n")
    (should (approx-equal (buffer-line-statistics) '(3 6 4))))

  (with-temp-buffer
    (insert "\n\n\n")
    (should (approx-equal (buffer-line-statistics) '(3 0 0)))))

(ert-deftest test-buffer-line-stats-gap ()
  (with-temp-buffer
    (dotimes (_ 1000)
      (insert "12345678901234567890123456789012345678901234567890\n"))
    (goto-char (point-min))
    ;; This should make a gap appear.
    (insert "123\n")
    (delete-region (point-min) (point))
    (should (approx-equal (buffer-line-statistics) '(1000 50 50.0))))
  (with-temp-buffer
    (dotimes (_ 1000)
      (insert "12345678901234567890123456789012345678901234567890\n"))
    (goto-char (point-min))
    (insert "123\n")
    (should (approx-equal (buffer-line-statistics) '(1001 50 49.9))))
  (with-temp-buffer
    (dotimes (_ 1000)
      (insert "12345678901234567890123456789012345678901234567890\n"))
    (goto-char (point-min))
    (insert "123\n")
    (goto-char (point-max))
    (insert "fóo")
    (should (approx-equal (buffer-line-statistics) '(1002 50 49.9)))))

(ert-deftest test-line-number-at-position ()
  (with-temp-buffer
    (insert (make-string 10 ?\n))
    (should (= (line-number-at-pos (point)) 11))
    (should (= (line-number-at-pos nil) 11))
    (should-error (line-number-at-pos -1))
    (should-error (line-number-at-pos 100))))