1 files changed, 953 insertions, 106 deletions
diff --git a/test/src/fns-tests.el b/test/src/fns-tests.el
index d751acb7478..fe8df7097a7 100644
--- a/test/src/fns-tests.el
+++ b/test/src/fns-tests.el
@@ -1,21 +1,21 @@
-;;; fns-tests.el --- tests for src/fns.c
+;;; fns-tests.el --- tests for src/fns.c  -*- lexical-binding:t -*-
 
-;; Copyright (C) 2014-2017 Free Software Foundation, Inc.
+;; Copyright (C) 2014-2022 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.
-;;
+;; GNU Emacs 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.
+
+;; GNU Emacs 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/'.
+;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
 
 ;;; Commentary:
 
@@ -23,6 +23,67 @@
 
 (require 'cl-lib)
 
+(ert-deftest fns-tests-identity ()
+  (let ((num 12345)) (should (eq (identity num) num)))
+  (let ((str "foo")) (should (eq (identity str) str)))
+  (let ((lst '(11))) (should (eq (identity lst) lst))))
+
+(ert-deftest fns-tests-random ()
+  (should (integerp (random)))
+  (should (>= (random 10) 0))
+  (should (< (random 10) 10)))
+
+(ert-deftest fns-tests-length ()
+  (should (= (length nil) 0))
+  (should (= (length '(1 2 3)) 3))
+  (should (= (length '[1 2 3]) 3))
+  (should (= (length "foo") 3))
+  (should-error (length t)))
+
+(ert-deftest fns-tests-safe-length ()
+  (should (= (safe-length '(1 2 3)) 3)))
+
+(ert-deftest fns-tests-string-bytes ()
+  (should (= (string-bytes "abc") 3)))
+
+;; 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-equal-including-properties ()
+  (should (equal-including-properties "" ""))
+  (should (equal-including-properties "foo" "foo"))
+  (should (equal-including-properties #("foo" 0 3 (a b))
+                                      (propertize "foo" 'a 'b)))
+  (should (equal-including-properties #("foo" 0 3 (a b c d))
+                                      (propertize "foo" 'a 'b 'c 'd)))
+  (should (equal-including-properties #("a" 0 1 (k v))
+                                      #("a" 0 1 (k v))))
+  (should-not (equal-including-properties #("a" 0 1 (k v))
+                                          #("a" 0 1 (k x))))
+  (should-not (equal-including-properties #("a" 0 1 (k v))
+                                          #("b" 0 1 (k v))))
+  (should-not (equal-including-properties #("foo" 0 3 (a b c e))
+                                          (propertize "foo" 'a 'b 'c 'd))))
+
+(ert-deftest fns-tests-equal-including-properties/string-prop-vals ()
+  "Handle string property values.  (Bug#6581)"
+  (should (equal-including-properties #("a" 0 1 (k "v"))
+                                      #("a" 0 1 (k "v"))))
+  (should (equal-including-properties #("foo" 0 3 (a (t)))
+                                      (propertize "foo" 'a (list t))))
+  (should-not (equal-including-properties #("a" 0 1 (k "v"))
+                                          #("a" 0 1 (k "x"))))
+  (should-not (equal-including-properties #("a" 0 1 (k "v"))
+                                          #("b" 0 1 (k "v")))))
+
 (ert-deftest fns-tests-reverse ()
   (should-error (reverse))
   (should-error (reverse 1))
@@ -38,21 +99,21 @@
   (should-error (nreverse))
   (should-error (nreverse 1))
   (should-error (nreverse (make-char-table 'foo)))
-  (should (equal (nreverse "xyzzy") "yzzyx"))
-  (let ((A []))
+  (should (equal (nreverse (copy-sequence "xyzzy")) "yzzyx"))
+  (let ((A (vector)))
     (nreverse A)
     (should (equal A [])))
-  (let ((A [0]))
+  (let ((A (vector 0)))
     (nreverse A)
     (should (equal A [0])))
-  (let ((A [1 2 3 4]))
+  (let ((A (vector 1 2 3 4)))
     (nreverse A)
     (should (equal A [4 3 2 1])))
-  (let ((A [1 2 3 4]))
+  (let ((A (vector 1 2 3 4)))
     (nreverse A)
     (nreverse A)
     (should (equal A [1 2 3 4])))
-  (let* ((A [1 2 3 4])
+  (let* ((A (vector 1 2 3 4))
 	 (B (nreverse (nreverse A))))
     (should (equal A B))))
 
@@ -69,6 +130,49 @@
     (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))))))
 
+(defconst fns-tests--string-lessp-cases
+  '((a 97 error)
+    (97 "a" error)
+    ("abc" "abd" t)
+    ("abd" "abc" nil)
+    (abc "abd" t)
+    ("abd" abc nil)
+    (abc abd t)
+    (abd abc nil)
+    ("" "" nil)
+    ("" " " t)
+    (" " "" nil)
+    ("abc" "abcd" t)
+    ("abcd" "abc" nil)
+    ("abc" "abc" nil)
+    (abc abc nil)
+    ("\0" "" nil)
+    ("" "\0" t)
+    ("~" "\x80" t)
+    ("\x80" "\x80" nil)
+    ("\xfe" "\xff" t)
+    ("Munchen" "München" t)
+    ("München" "Munchen" nil)
+    ("München" "München" nil)
+    ("Ré" "Réunion" t)))
+
+
+(ert-deftest fns-tests-string-lessp ()
+  ;; Exercise both `string-lessp' and its alias `string<', both directly
+  ;; and in a function (exercising its bytecode).
+  (dolist (lessp (list #'string-lessp #'string<
+                       (lambda (a b) (string-lessp a b))
+                       (lambda (a b) (string< a b))))
+    (ert-info ((prin1-to-string lessp) :prefix "function: ")
+      (dolist (case fns-tests--string-lessp-cases)
+        (ert-info ((prin1-to-string case) :prefix "case: ")
+          (pcase case
+            (`(,x ,y error)
+             (should-error (funcall lessp x y)))
+            (`(,x ,y ,expected)
+             (should (equal (funcall lessp x y) expected)))))))))
+
+
 (ert-deftest fns-tests-compare-strings ()
   (should-error (compare-strings))
   (should-error (compare-strings "xyzzy" "xyzzy"))
@@ -119,10 +223,9 @@
 
   ;; In POSIX or C locales, collation order is lexicographic.
   (should (string-collate-lessp "XYZZY" "xyzzy" "POSIX"))
-  ;; In a language specific locale, collation order is different.
-  (should (string-collate-lessp
-	   "xyzzy" "XYZZY"
-	   (if (eq system-type 'windows-nt) "enu_USA" "en_US.UTF-8")))
+  ;; 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))
@@ -136,14 +239,84 @@
 ;; Invalid UTF-8 sequences shall be indicated.  How to create such strings?
 
 (ert-deftest fns-tests-sort ()
-  (should (equal (sort '(9 5 2 -1 5 3 8 7 4) (lambda (x y) (< x y)))
+  (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 '(9 5 2 -1 5 3 8 7 4) (lambda (x y) (> x y)))
+  (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 '[9 5 2 -1 5 3 8 7 4] (lambda (x y) (< x y)))
+  (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 '[9 5 2 -1 5 3 8 7 4] (lambda (x y) (> x y)))
+  (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]))
+  ;; Sort a reversed list and vector.
+  (should (equal
+	 (sort (reverse (number-sequence 1 1000)) (lambda (x y) (< x y)))
+	 (number-sequence 1 1000)))
+  (should (equal
+	   (sort (reverse (vconcat (number-sequence 1 1000)))
+                 (lambda (x y) (< x y)))
+	 (vconcat (number-sequence 1 1000))))
+  ;; Sort a constant list and vector.
+  (should (equal
+           (sort (make-vector 100 1) (lambda (x y) (> x y)))
+           (make-vector 100 1)))
+  (should (equal
+           (sort (append (make-vector 100 1) nil) (lambda (x y) (> x y)))
+           (append (make-vector 100 1) nil)))
+  ;; Sort a long list and vector with every pair reversed.
+  (let ((vec (make-vector 100000 nil))
+        (logxor-vec (make-vector 100000 nil)))
+    (dotimes (i 100000)
+      (aset logxor-vec i  (logxor i 1))
+      (aset vec i i))
+    (should (equal
+             (sort logxor-vec (lambda (x y) (< x y)))
+             vec))
+    (should (equal
+             (sort (append logxor-vec nil) (lambda (x y) (< x y)))
+             (append vec nil))))
+  ;; Sort a list and vector with seven swaps.
+  (let ((vec (make-vector 100 nil))
+        (swap-vec (make-vector 100 nil)))
+    (dotimes (i 100)
+      (aset vec i (- i 50))
+      (aset swap-vec i (- i 50)))
+    (mapc (lambda (p)
+	(let ((tmp (elt swap-vec (car p))))
+	  (aset swap-vec (car p) (elt swap-vec (cdr p)))
+	  (aset swap-vec (cdr p) tmp)))
+          '((48 . 94) (75 . 77) (33 . 41) (92 . 52)
+            (10 . 96) (1 . 14) (43 . 81)))
+    (should (equal
+             (sort (copy-sequence swap-vec) (lambda (x y) (< x y)))
+             vec))
+    (should (equal
+             (sort (append swap-vec nil) (lambda (x y) (< x y)))
+             (append vec nil))))
+  ;; Check for possible corruption after GC.
+  (let* ((size 3000)
+         (complex-vec (make-vector size nil))
+         (vec (make-vector size nil))
+         (counter 0)
+         (my-counter (lambda ()
+                       (if (< counter 500)
+                           (cl-incf counter)
+                         (setq counter 0)
+                         (garbage-collect))))
+         (rand 1)
+         (generate-random
+	  (lambda () (setq rand
+                           (logand (+ (* rand 1103515245) 12345)  2147483647)))))
+    ;; Make a complex vector and its sorted version.
+    (dotimes (i size)
+      (let ((r (funcall generate-random)))
+        (aset complex-vec i (cons r "a"))
+        (aset vec i (cons r "a"))))
+    ;; Sort it.
+    (should (equal
+             (sort complex-vec
+                   (lambda (x y) (funcall my-counter) (< (car x) (car y))))
+             (sort vec 'car-less-than-car))))
+  ;; Check for sorting stability.
   (should (equal
 	   (sort
 	    (vector
@@ -151,45 +324,51 @@
 	     '(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")])))
+	    (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 ()
-  ;; See https://lists.gnu.org/archive/html/emacs-devel/2015-10/msg02505.html.
-  :expected-result (if (eq system-type 'cygwin) :failed :passed)
   (skip-unless (fns-tests--collate-enabled-p))
 
   ;; Punctuation and whitespace characters are relevant for POSIX.
   (should
    (equal
-    (sort '("11" "12" "1 1" "1 2" "1.1" "1.2")
+    (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.
-  (should
-   (equal
-    (sort '("11" "12" "1 1" "1 2" "1.1" "1.2")
-	  (lambda (a b)
-	    (let ((w32-collate-ignore-punctuation t))
-	      (string-collate-lessp
-	       a b (if (eq system-type 'windows-nt) "enu_USA" "en_US.UTF-8")))))
-    '("11" "1 1" "1.1" "12" "1 2" "1.2")))
+  ;; 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 '("Ævar" "Agustín" "Adrian" "Eli")
+    (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.
-  (should
-   (equal
-    (sort '("Ævar" "Agustín" "Adrian" "Eli")
-	  (lambda (a b)
-	    (let ((w32-collate-ignore-punctuation t))
-	      (string-collate-lessp
-	       a b (if (eq system-type 'windows-nt) "enu_USA" "en_US.UTF-8")))))
-    '("Adrian" "Ævar" "Agustín" "Eli"))))
+  ;; 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"))
@@ -198,7 +377,7 @@
   (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 '("foo12.png" "foo2.png" "foo1.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"))
@@ -214,11 +393,200 @@
   (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 (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/"))
+
+  (should-error (base64-encode-string "ƒ"))
+  (should-error (base64-encode-string "ü")))
+
+(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)))
+
+  (should-error (fns-tests--with-region base64url-encode-region "ƒ"))
+  (should-error (fns-tests--with-region base64url-encode-region "ü")))
+
+
+(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)))
+
+  (should-error (base64url-encode-string "ƒ"))
+  (should-error (base64url-encode-string "ü")))
+
+(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
@@ -235,13 +603,30 @@
                    (buffer-hash))
                  (sha1 "foo"))))
 
+(ert-deftest fns-tests-mapconcat ()
+  (should (string= (mapconcat #'identity '()) ""))
+  (should (string= (mapconcat #'identity '("a" "b")) "ab"))
+  (should (string= (mapconcat #'identity '() "_") ""))
+  (should (string= (mapconcat #'identity '("A") "_") "A"))
+  (should (string= (mapconcat #'identity '("A" "B") "_") "A_B"))
+  (should (string= (mapconcat #'identity '("A" "B" "C") "_") "A_B_C"))
+  ;; non-ASCII strings
+  (should (string= (mapconcat #'identity '("Ä" "ø" "☭" "தமிழ்") "_漢字_")
+                   "Ä_漢字_ø_漢字_☭_漢字_தமிழ்"))
+  ;; vector
+  (should (string= (mapconcat #'identity ["a" "b"]) "ab"))
+  ;; bool-vector
+  (should (string= (mapconcat #'identity [nil nil]) ""))
+  (should-error (mapconcat #'identity [nil nil t])
+                :type 'wrong-type-argument))
+
 (ert-deftest fns-tests-mapcan ()
   (should-error (mapcan))
   (should-error (mapcan #'identity))
   (should-error (mapcan #'identity (make-char-table 'foo)))
-  (should (equal (mapcan #'list '(1 2 3)) '(1 2 3)))
+  (should (equal (mapcan #'list (list 1 2 3)) '(1 2 3)))
   ;; `mapcan' is destructive
-  (let ((data '((foo) (bar))))
+  (let ((data (list (list 'foo) (list 'bar))))
     (should (equal (mapcan #'identity data) '(foo bar)))
     (should (equal data                     '((foo bar) (bar))))))
 
@@ -467,24 +852,6 @@
     (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))
@@ -521,24 +888,6 @@
     (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))))
@@ -548,31 +897,529 @@
   (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."
+  "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)))))
 
-(provide 'fns-tests)
+(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")))
+
+  ;; correct behavior with empty strings
+  (should (equal 0 (string-distance "" "")))
+  (should (equal 0 (string-distance "" "" t)))
+  (should (equal 1 (string-distance "x" "")))
+  (should (equal 1 (string-distance "x" "" t)))
+  (should (equal 1 (string-distance "" "x")))
+  (should (equal 1 (string-distance "" "x" t))))
+
+(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))))
+
+(defun fns-tests-concat (&rest args)
+  ;; Dodge the byte-compiler's partial evaluation of `concat' with
+  ;; constant arguments.
+  (apply #'concat args))
+
+(ert-deftest fns-concat ()
+  (should (equal (fns-tests-concat) ""))
+  (should (equal (fns-tests-concat "") ""))
+  (should (equal (fns-tests-concat nil) ""))
+  (should (equal (fns-tests-concat []) ""))
+  (should (equal (fns-tests-concat [97 98]) "ab"))
+  (should (equal (fns-tests-concat '(97 98)) "ab"))
+  (should (equal (fns-tests-concat "ab" '(99 100) nil [101 102] "gh")
+                 "abcdefgh"))
+  (should (equal (fns-tests-concat "Ab" "\200" "cd") "Ab\200cd"))
+  (should (equal (fns-tests-concat "aB" "\200" "çd") "aB\200çd"))
+  (should (equal (fns-tests-concat "AB" (string-to-multibyte "\200") "cd")
+                 (string-to-multibyte "AB\200cd")))
+  (should (equal (fns-tests-concat "ab" '(#xe5) [255] "cd") "abåÿcd"))
+  (should (equal (fns-tests-concat '(#x3fffff) [#x3fff80] "xy") "\377\200xy"))
+  (should (equal (fns-tests-concat '(#x3fffff) [#x3fff80] "xy§") "\377\200xy§"))
+  (should (equal-including-properties
+           (fns-tests-concat #("abc" 0 3 (a 1)) #("de" 0 2 (a 1)))
+           #("abcde" 0 5 (a 1))))
+  (should (equal-including-properties
+           (fns-tests-concat #("abc" 0 3 (a 1)) "§ü" #("çå" 0 2 (b 2)))
+           #("abc§üçå" 0 3 (a 1) 5 7 (b 2))))
+  (should-error (fns-tests-concat "a" '(98 . 99))
+                :type 'wrong-type-argument)
+  (let ((loop (list 66 67)))
+    (setcdr (cdr loop) loop)
+    (should-error (fns-tests-concat "A" loop)
+                  :type 'circular-list)))
+
+(ert-deftest fns-vconcat ()
+  (should (equal (vconcat) []))
+  (should (equal (vconcat nil) []))
+  (should (equal (vconcat "") []))
+  (should (equal (vconcat [1 2 3]) [1 2 3]))
+  (should (equal (vconcat '(1 2 3)) [1 2 3]))
+  (should (equal (vconcat "ABC") [65 66 67]))
+  (should (equal (vconcat "ü§") [252 167]))
+  (should (equal (vconcat [1 2 3] nil '(4 5) "AB" "å"
+                          "\377" (string-to-multibyte "\377")
+                          (bool-vector t nil nil t nil))
+                 [1 2 3 4 5 65 66 #xe5 255 #x3fffff t nil nil t nil]))
+  (should-error (vconcat [1] '(2 . 3))
+                :type 'wrong-type-argument)
+  (let ((loop (list 1 2)))
+    (setcdr (cdr loop) loop)
+    (should-error (vconcat [1] loop)
+                  :type 'circular-list)))
+
+(ert-deftest fns-append ()
+  (should (equal (append) nil))
+  (should (equal (append 'tail) 'tail))
+  (should (equal (append [1 2 3] nil '(4 5) "AB" "å"
+                         "\377" (string-to-multibyte "\377")
+                          (bool-vector t nil nil t nil)
+                         '(9 10))
+                 '(1 2 3 4 5 65 66 #xe5 255 #x3fffff t nil nil t nil 9 10)))
+  (should (equal (append '(1 2) '(3 4) 'tail)
+                 '(1 2 3 4 . tail)))
+  (should-error (append '(1 . 2) '(3))
+                :type 'wrong-type-argument)
+  (let ((loop (list 1 2)))
+    (setcdr (cdr loop) loop)
+    (should-error (append loop '(end))
+                  :type 'circular-list)))
+
+(ert-deftest test-plist ()
+  (let ((plist '(:a "b")))
+    (setq plist (plist-put plist :b "c"))
+    (should (equal (plist-get plist :b) "c"))
+    (should (equal (plist-member plist :b) '(:b "c"))))
+
+  (let ((plist '("1" "2" "a" "b")))
+    (setq plist (plist-put plist (copy-sequence "a") "c"))
+    (should-not (equal (plist-get plist (copy-sequence "a")) "c"))
+    (should-not (equal (plist-member plist (copy-sequence "a")) '("a" "c"))))
+
+  (let ((plist '("1" "2" "a" "b")))
+    (setq plist (plist-put plist (copy-sequence "a") "c" #'equal))
+    (should (equal (plist-get plist (copy-sequence "a") #'equal) "c"))
+    (should (equal (plist-member plist (copy-sequence "a") #'equal)
+                   '("a" "c")))))
+
+(ert-deftest fns--string-to-unibyte-multibyte ()
+  (dolist (str (list "" "a" "abc" "a\x00\x7fz" "a\xaa\xbbz" "\x80\xdd\xff"
+                     (apply #'unibyte-string (number-sequence 0 255))))
+    (ert-info ((prin1-to-string str) :prefix "str: ")
+      (should-not (multibyte-string-p str))
+      (let* ((u (string-to-unibyte str))   ; should be identity
+             (m (string-to-multibyte u))   ; lossless conversion
+             (mm (string-to-multibyte m))  ; should be identity
+             (uu (string-to-unibyte m))    ; also lossless
+             (ml (mapcar (lambda (c) (if (<= c #x7f) c (+ c #x3fff00))) u)))
+        (should-not (multibyte-string-p u))
+        (should (multibyte-string-p m))
+        (should (multibyte-string-p mm))
+        (should-not (multibyte-string-p uu))
+        (should (equal str u))
+        (should (equal m mm))
+        (should (equal str uu))
+        (should (equal (append m nil) ml)))))
+  (should-error (string-to-unibyte "å"))
+  (should-error (string-to-unibyte "ABC∀BC")))
+
+(defun fns-tests--take-ref (n list)
+  "Reference implementation of `take'."
+  (named-let loop ((m n) (tail list) (ac nil))
+    (if (and (> m 0) tail)
+        (loop (1- m) (cdr tail) (cons (car tail) ac))
+      (nreverse ac))))
+
+(ert-deftest fns--take-ntake ()
+  "Test `take' and `ntake'."
+  ;; Check errors and edge cases.
+  (should-error (take 'x '(a)))
+  (should-error (ntake 'x '(a)))
+  (should-error (take 1 'a))
+  (should-error (ntake 1 'a))
+  (should-error (take 2 '(a . b)))
+  (should-error (ntake 2 '(a . b)))
+  ;; Tolerate non-lists for a count of zero.
+  (should (equal (take 0 'a) nil))
+  (should (equal (ntake 0 'a) nil))
+  ;; But not non-numbers for empty lists.
+  (should-error (take 'x nil))
+  (should-error (ntake 'x nil))
+
+  (dolist (list '(nil (a) (a b) (a b c) (a b c d) (a . b) (a b . c)))
+    (ert-info ((prin1-to-string list) :prefix "list: ")
+      (let ((max (if (proper-list-p list)
+                     (+ 2 (length list))
+                   (safe-length list))))
+        (dolist (n (number-sequence -1 max))
+          (ert-info ((prin1-to-string n) :prefix "n: ")
+            (let* ((l (copy-tree list))
+                   (ref (fns-tests--take-ref n l)))
+              (should (equal (take n l) ref))
+              (should (equal l list))
+              (should (equal (ntake n l) ref))))))))
+
+  ;; Circular list.
+  (let ((list (list 'a 'b 'c)))
+    (setcdr (nthcdr 2 list) (cdr list)) ; list now (a b c b c b c ...)
+    (should (equal (take 0 list) nil))
+    (should (equal (take 1 list) '(a)))
+    (should (equal (take 2 list) '(a b)))
+    (should (equal (take 3 list) '(a b c)))
+    (should (equal (take 4 list) '(a b c b)))
+    (should (equal (take 5 list) '(a b c b c)))
+    (should (equal (take 10 list) '(a b c b c b c b c b)))
+
+    (should (equal (ntake 10 list) '(a b))))
+
+  ;; Bignum N argument.
+  (let ((list (list 'a 'b 'c)))
+    (should (equal (take (+ most-positive-fixnum 1) list) '(a b c)))
+    (should (equal (take (- most-negative-fixnum 1) list) nil))
+    (should (equal (ntake (+ most-positive-fixnum 1) list) '(a b c)))
+    (should (equal (ntake (- most-negative-fixnum 1) list) nil))
+    (should (equal list '(a b c)))))
+
+;;; fns-tests.el ends here