Various json.el improvements

* etc/NEWS: Announce that json-read-number is now stricter.

* json.el: Bump package version.
(json-encoding-lisp-style-closings, json-pre-element-read-function)
(json-post-element-read-function, json-advance, json-peek)
(json--path): Clarify and improve style of doc strings.
(json-join): Define as an obsolete alias of string-join.
(json-alist-p, json-plist-p): Refactor for speed and declare as
pure, side-effect-free, and error-free.
(json--plist-reverse): Rename function...
(json--plist-nreverse): ...to this, making it destructive for speed.
All callers changed.
(json--plist-to-alist): Remove, replacing single use with map-pairs.
(json--with-indentation): Accept multiple forms as arguments, fix
their indentation, and allow them to be instrumented for debugging.
Add docstring.
(json-pop, json-read-keyword, json-add-to-object)
(json-encode-array): Simplify for speed.
(json-skip-whitespace): Put newline before carriage return for
likely frequency of occurrence, and so that the characters appear in
increasing order.
(json--check-position): Use 1+.
(json-path-to-position): Open code apply-partially.
(json-keywords): Turn into a defconst and mark as obsolete now that
it is no longer used.
(json--post-value, json--number, json--escape): New rx definitions.
(json-encode-keyword): Declare as side-effect-free.
(json-read-number): Reject leading zeros and plus signs, and make
integer part mandatory in accordance with JSON standards and for
consistency with native JSON parsing functions.  Eagerly signal
json-number-format when garbage follows a valid number, e.g., when
reading "1.1.1", instead of leaving that up to the caller.  Remove
optional internal argument from advertised calling convention now
that the function is no longer recursive.
(json-encode-number): Define as an alias of number-to-string.
(json-special-chars): Turn into a defconst.
(json-read-escaped-char, json-new-object, json-read-file)
(json-pretty-print): Simplify.
(json-read-string): For consistency with other json.el error
reporting, remove check for leading '"', and use the integer value
rather than the printed representation of characters in error data.
At EOB signal json-end-of-file instead of json-string-format.
(json--long-string-threshold, json--string-buffer): New variables.
(json-encode-string): Reimplement in terms of buffer manipulation
for speed (bug#20154).
(json-read-object): Escape ?\} properly.
(json--encode-alist): New function extracted from json-encode-alist.
(json-encode-hash-table, json-encode-alist, json-encode-plist): Use
it to avoid destructively modifying the argument when
json-encoding-object-sort-predicate is non-nil without incurring
unnecessary copying (bug#40693).  Encode empty object as "{}" even
when pretty-printing.  Simplify for speed.
(json-read-array): Avoid recomputing list length on each iteration
when json-pre-element-read-function is non-nil.  Make first element
of json-array-format error data a string for consistency with
json-object-format and to make the displayed error message clearer.
(json-readtable-dispatch): Accept any kind of argument, not just
symbols.  Generate the table in a simpler manner so the dispatch
order is clearer.  Remove dispatch on ?+ and ?. now that
json-read-number is stricter and for consistency with native JSON
parsing functions.  Signal json-end-of-file if argument is nil.
(json-read): Simplify accordingly.
(json-encode): Avoid allocating a list on each invocation.

* lisp/jsonrpc.el (jsonrpc--json-read, jsonrpc--json-encode): Check
whether native JSON functions are fboundp only once, at load time.

* lisp/progmodes/python.el (python--parse-json-array): New function.
(python-shell-prompt-detect): Use it to parse JSON directly as a
list rather than converting from a vector.

* test/lisp/json-tests.el (json-tests--with-temp-buffer): Allow
instrumenting for debugging.
(test-json-join, test-json-plist-to-alist): Remove tests.

(test-json-alist-p, test-json-plist-p, test-json-advance)
(test-json-peek, test-json-pop, test-json-skip-whitespace)
(test-json-read-keyword, test-json-encode-keyword)
(test-json-encode-number, test-json-read-escaped-char)
(test-json-read-string, test-json-encode-string)
(test-json-encode-key, test-json-new-object)
(test-json-encode-hash-table, test-json-encode-plist)
(test-json-encode-list, test-json-read-array)
(test-json-encode-array, test-json-read)
(test-json-read-from-string, test-json-encode): Extend tests.

(test-json-plist-reverse): Rename test...
(test-json-plist-nreverse): ...to this and avoid modifying literal
lists.
(test-json-read-number): Rename test...
(test-json-read-integer): ...to this, focusing on integers.
(test-json-add-to-object): Rename test...
(test-json-add-to-alist): ...to this, focusing on alists.
(json-encode-simple-alist): Rename test...
(test-json-encode-alist): ...to this, extending it.
(test-json-encode-alist-with-sort-predicate): Rename test...
(test-json-encode-alist-sort): ...to this, extending it.
(test-json-encode-plist-with-sort-predicate): Rename test...
(test-json-encode-plist-sort): ...to this, extending it.

(test-json-read-keyword-invalid, test-json-read-fraction)
(test-json-read-exponent, test-json-read-fraction-exponent)
(test-json-read-number-invalid)
(test-json-read-escaped-char-invalid, test-json-add-to-plist)
(test-json-add-to-hash-table, test-json-read-object-empty)
(test-json-read-object-invalid, test-json-read-object-function)
(test-json-encode-hash-table-pretty)
(test-json-encode-hash-table-lisp-style)
(test-json-encode-hash-table-sort, test-json-encode-alist-pretty)
(test-json-encode-alist-lisp-style, test-json-encode-plist-pretty)
(test-json-encode-plist-lisp-style, test-json-read-array-function)
(test-json-encode-array-pretty, test-json-encode-array-lisp-style)
(test-json-read-invalid): New tests.

(test-json-path-to-position-no-match): Use should-not.
(test-json-read-object): Move error check to new test
test-json-read-object-invalid.
(test-json-pretty-print-object): Adapt test now that empty objects
are pretty-printed as "{}".

1 files changed, 722 insertions, 143 deletions

diff --git a/test/lisp/json-tests.el b/test/lisp/json-tests.el
index ac9706a8ae7..a0e8c87c7b3 100644
--- a/test/lisp/json-tests.el
+++ b/test/lisp/json-tests.el
@@ -21,11 +21,16 @@
 
 (require 'ert)
 (require 'json)
+(require 'map)
+(require 'seq)
+
+(eval-when-compile
+  (require 'cl-lib))
 
 (defmacro json-tests--with-temp-buffer (content &rest body)
   "Create a temporary buffer with CONTENT and evaluate BODY there.
 Point is moved to beginning of the buffer."
-  (declare (indent 1))
+  (declare (debug t) (indent 1))
   `(with-temp-buffer
      (insert ,content)
      (goto-char (point-min))
@@ -33,66 +38,107 @@ Point is moved to beginning of the buffer."
 
 ;;; Utilities
 
-(ert-deftest test-json-join ()
-  (should (equal (json-join '() ", ")  ""))
-  (should (equal (json-join '("a" "b" "c") ", ")  "a, b, c")))
-
 (ert-deftest test-json-alist-p ()
   (should (json-alist-p '()))
-  (should (json-alist-p '((a 1) (b 2) (c 3))))
-  (should (json-alist-p '((:a 1) (:b 2) (:c 3))))
-  (should (json-alist-p '(("a" 1) ("b" 2) ("c" 3))))
+  (should (json-alist-p '((()))))
+  (should (json-alist-p '((a))))
+  (should (json-alist-p '((a . 1))))
+  (should (json-alist-p '((a . 1) (b 2) (c))))
+  (should (json-alist-p '((:a) (:b 2) (:c . 3))))
+  (should (json-alist-p '(("a" . 1) ("b" 2) ("c"))))
+  (should-not (json-alist-p '(())))
+  (should-not (json-alist-p '(a)))
+  (should-not (json-alist-p '(a . 1)))
+  (should-not (json-alist-p '((a . 1) . [])))
+  (should-not (json-alist-p '((a . 1) [])))
   (should-not (json-alist-p '(:a :b :c)))
   (should-not (json-alist-p '(:a 1 :b 2 :c 3)))
-  (should-not (json-alist-p '((:a 1) (:b 2) 3))))
+  (should-not (json-alist-p '((:a 1) (:b 2) 3)))
+  (should-not (json-alist-p '((:a 1) (:b 2) ())))
+  (should-not (json-alist-p '(((a) 1) (b 2) (c 3))))
+  (should-not (json-alist-p []))
+  (should-not (json-alist-p [(a . 1)]))
+  (should-not (json-alist-p #s(hash-table))))
 
 (ert-deftest test-json-plist-p ()
   (should (json-plist-p '()))
+  (should (json-plist-p '(:a 1)))
   (should (json-plist-p '(:a 1 :b 2 :c 3)))
+  (should (json-plist-p '(:a :b)))
+  (should (json-plist-p '(:a :b :c :d)))
+  (should-not (json-plist-p '(a)))
+  (should-not (json-plist-p '(a 1)))
   (should-not (json-plist-p '(a 1 b 2 c 3)))
   (should-not (json-plist-p '("a" 1 "b" 2 "c" 3)))
+  (should-not (json-plist-p '(:a)))
   (should-not (json-plist-p '(:a :b :c)))
-  (should-not (json-plist-p '((:a 1) (:b 2) (:c 3)))))
-
-(ert-deftest test-json-plist-reverse ()
-  (should (equal (json--plist-reverse '()) '()))
-  (should (equal (json--plist-reverse '(:a 1)) '(:a 1)))
-  (should (equal (json--plist-reverse '(:a 1 :b 2 :c 3))
+  (should-not (json-plist-p '(:a 1 :b 2 :c)))
+  (should-not (json-plist-p '((:a 1))))
+  (should-not (json-plist-p '((:a 1) (:b 2) (:c 3))))
+  (should-not (json-plist-p []))
+  (should-not (json-plist-p [:a 1]))
+  (should-not (json-plist-p #s(hash-table))))
+
+(ert-deftest test-json-plist-nreverse ()
+  (should (equal (json--plist-nreverse '()) '()))
+  (should (equal (json--plist-nreverse (list :a 1)) '(:a 1)))
+  (should (equal (json--plist-nreverse (list :a 1 :b 2)) '(:b 2 :a 1)))
+  (should (equal (json--plist-nreverse (list :a 1 :b 2 :c 3))
                  '(:c 3 :b 2 :a 1))))
 
-(ert-deftest test-json-plist-to-alist ()
-  (should (equal (json--plist-to-alist '()) '()))
-  (should (equal (json--plist-to-alist '(:a 1)) '((:a . 1))))
-  (should (equal (json--plist-to-alist '(:a 1 :b 2 :c 3))
-                 '((:a . 1) (:b . 2) (:c . 3)))))
-
 (ert-deftest test-json-advance ()
   (json-tests--with-temp-buffer "{ \"a\": 1 }"
     (json-advance 0)
-    (should (= (point) (point-min)))
+    (should (bobp))
+    (json-advance)
+    (should (= (point) (1+ (point-min))))
+    (json-advance 0)
+    (should (= (point) (1+ (point-min))))
+    (json-advance 1)
+    (should (= (point) (+ (point-min) 2)))
     (json-advance 3)
-    (should (= (point) (+ (point-min) 3)))))
+    (should (= (point) (+ (point-min) 5)))))
 
 (ert-deftest test-json-peek ()
   (json-tests--with-temp-buffer ""
     (should (zerop (json-peek))))
   (json-tests--with-temp-buffer "{ \"a\": 1 }"
-    (should (equal (json-peek) ?{))))
+    (should (= (json-peek) ?\{))
+    (goto-char (1- (point-max)))
+    (should (= (json-peek) ?\}))
+    (json-advance)
+    (should (zerop (json-peek)))))
 
 (ert-deftest test-json-pop ()
   (json-tests--with-temp-buffer ""
     (should-error (json-pop) :type 'json-end-of-file))
   (json-tests--with-temp-buffer "{ \"a\": 1 }"
-    (should (equal (json-pop) ?{))
-    (should (= (point) (+ (point-min) 1)))))
+    (should (= (json-pop) ?\{))
+    (should (= (point) (1+ (point-min))))
+    (goto-char (1- (point-max)))
+    (should (= (json-pop) ?\}))
+    (should-error (json-pop) :type 'json-end-of-file)))
 
 (ert-deftest test-json-skip-whitespace ()
+  (json-tests--with-temp-buffer ""
+    (json-skip-whitespace)
+    (should (bobp))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "{}"
+    (json-skip-whitespace)
+    (should (bobp))
+    (json-advance)
+    (json-skip-whitespace)
+    (should (= (point) (1+ (point-min))))
+    (json-advance)
+    (json-skip-whitespace)
+    (should (eobp)))
   (json-tests--with-temp-buffer "\t\r\n\f\b { \"a\": 1 }"
     (json-skip-whitespace)
-    (should (equal (char-after) ?\f)))
+    (should (= (json-peek) ?\f)))
   (json-tests--with-temp-buffer "\t\r\n\t { \"a\": 1 }"
     (json-skip-whitespace)
-    (should (equal (char-after) ?{))))
+    (should (= (json-peek) ?\{))))
 
 ;;; Paths
 
@@ -113,59 +159,243 @@ Point is moved to beginning of the buffer."
 (ert-deftest test-json-path-to-position-no-match ()
   (let* ((json-string "{\"foo\": {\"bar\": \"baz\"}}")
          (matched-path (json-path-to-position 5 json-string)))
-    (should (null matched-path))))
+    (should-not matched-path)))
 
 ;;; Keywords
 
 (ert-deftest test-json-read-keyword ()
   (json-tests--with-temp-buffer "true"
-    (should (json-read-keyword "true")))
+    (should (eq (json-read-keyword "true") t))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "true "
+    (should (eq (json-read-keyword "true") t))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "true}"
+    (should (eq (json-read-keyword "true") t))
+    (should (= (point) (+ (point-min) 4))))
+  (json-tests--with-temp-buffer "true false"
+    (should (eq (json-read-keyword "true") t))
+    (should (= (point) (+ (point-min) 5))))
+  (json-tests--with-temp-buffer "true }"
+    (should (eq (json-read-keyword "true") t))
+    (should (= (point) (+ (point-min) 5))))
+  (json-tests--with-temp-buffer "true |"
+    (should (eq (json-read-keyword "true") t))
+    (should (= (point) (+ (point-min) 5))))
+  (json-tests--with-temp-buffer "false"
+    (let ((json-false 'false))
+      (should (eq (json-read-keyword "false") 'false)))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "null"
+    (let ((json-null 'null))
+      (should (eq (json-read-keyword "null") 'null)))
+    (should (eobp))))
+
+(ert-deftest test-json-read-keyword-invalid ()
+  (json-tests--with-temp-buffer ""
+    (should (equal (should-error (json-read-keyword ""))
+                   '(json-unknown-keyword "")))
+    (should (equal (should-error (json-read-keyword "true"))
+                   '(json-unknown-keyword ()))))
   (json-tests--with-temp-buffer "true"
-    (should-error
-     (json-read-keyword "false") :type 'json-unknown-keyword))
+    (should (equal (should-error (json-read-keyword "false"))
+                   '(json-unknown-keyword "true"))))
   (json-tests--with-temp-buffer "foo"
-    (should-error
-     (json-read-keyword "foo") :type 'json-unknown-keyword)))
+    (should (equal (should-error (json-read-keyword "foo"))
+                   '(json-unknown-keyword "foo")))
+    (should (equal (should-error (json-read-keyword "bar"))
+                   '(json-unknown-keyword "bar"))))
+  (json-tests--with-temp-buffer " true"
+    (should (equal (should-error (json-read-keyword "true"))
+                   '(json-unknown-keyword ()))))
+  (json-tests--with-temp-buffer "truefalse"
+    (should (equal (should-error (json-read-keyword "true"))
+                   '(json-unknown-keyword "truefalse"))))
+  (json-tests--with-temp-buffer "true|"
+    (should (equal (should-error (json-read-keyword "true"))
+                   '(json-unknown-keyword "true")))))
 
 (ert-deftest test-json-encode-keyword ()
   (should (equal (json-encode-keyword t) "true"))
-  (should (equal (json-encode-keyword json-false) "false"))
-  (should (equal (json-encode-keyword json-null) "null")))
+  (let ((json-false 'false))
+    (should (equal (json-encode-keyword 'false) "false"))
+    (should (equal (json-encode-keyword json-false) "false")))
+  (let ((json-null 'null))
+    (should (equal (json-encode-keyword 'null) "null"))
+    (should (equal (json-encode-keyword json-null) "null"))))
 
 ;;; Numbers
 
-(ert-deftest test-json-read-number ()
-  (json-tests--with-temp-buffer "3"
-    (should (= (json-read-number) 3)))
-  (json-tests--with-temp-buffer "-5"
-    (should (= (json-read-number) -5)))
-  (json-tests--with-temp-buffer "123.456"
-    (should (= (json-read-number) 123.456)))
-  (json-tests--with-temp-buffer "1e3"
-    (should (= (json-read-number) 1e3)))
-  (json-tests--with-temp-buffer "2e+3"
-    (should (= (json-read-number) 2e3)))
-  (json-tests--with-temp-buffer "3E3"
-    (should (= (json-read-number) 3e3)))
-  (json-tests--with-temp-buffer "1e-7"
-    (should (= (json-read-number) 1e-7)))
-  (json-tests--with-temp-buffer "abc"
-    (should-error (json-read-number) :type 'json-number-format)))
+(ert-deftest test-json-read-integer ()
+  (json-tests--with-temp-buffer "0 "
+    (should (= (json-read-number) 0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-0 "
+    (should (= (json-read-number) 0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "3 "
+    (should (= (json-read-number) 3))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-10 "
+    (should (= (json-read-number) -10))
+    (should (eobp)))
+  (json-tests--with-temp-buffer (format "%d " (1+ most-positive-fixnum))
+    (should (= (json-read-number) (1+ most-positive-fixnum)))
+    (should (eobp)))
+  (json-tests--with-temp-buffer (format "%d " (1- most-negative-fixnum))
+    (should (= (json-read-number) (1- most-negative-fixnum)))
+    (should (eobp))))
+
+(ert-deftest test-json-read-fraction ()
+  (json-tests--with-temp-buffer "0.0 "
+    (should (= (json-read-number) 0.0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-0.0 "
+    (should (= (json-read-number) 0.0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "0.01 "
+    (should (= (json-read-number) 0.01))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-0.01 "
+    (should (= (json-read-number) -0.01))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "123.456 "
+    (should (= (json-read-number) 123.456))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-123.456 "
+    (should (= (json-read-number) -123.456))
+    (should (eobp))))
+
+(ert-deftest test-json-read-exponent ()
+  (json-tests--with-temp-buffer "0e0 "
+    (should (= (json-read-number) 0e0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-0E0 "
+    (should (= (json-read-number) 0e0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-0E+0 "
+    (should (= (json-read-number) 0e0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "0e-0 "
+    (should (= (json-read-number) 0e0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "12e34 "
+    (should (= (json-read-number) 12e34))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-12E34 "
+    (should (= (json-read-number) -12e34))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-12E+34 "
+    (should (= (json-read-number) -12e34))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "12e-34 "
+    (should (= (json-read-number) 12e-34))
+    (should (eobp))))
+
+(ert-deftest test-json-read-fraction-exponent ()
+  (json-tests--with-temp-buffer "0.0e0 "
+    (should (= (json-read-number) 0.0e0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-0.0E0 "
+    (should (= (json-read-number) 0.0e0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "0.12E-0 "
+    (should (= (json-read-number) 0.12e0))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "-12.34e+56 "
+    (should (= (json-read-number) -12.34e+56))
+    (should (eobp))))
+
+(ert-deftest test-json-read-number-invalid ()
+  (cl-flet ((read (str)
+                  ;; Return error and point resulting from reading STR.
+                  (json-tests--with-temp-buffer str
+                    (cons (should-error (json-read-number)) (point)))))
+    ;; POS is where each of its STRINGS becomes invalid.
+    (pcase-dolist (`(,pos . ,strings)
+                   '((1 "" "+" "-" "." "e" "e1" "abc" "++0" "++1"
+                        "+0"  "+0.0" "+12" "+12.34" "+12.34e56"
+                        ".0" "+.0" "-.0" ".12" "+.12" "-.12"
+                        ".e0" "+.e0" "-.e0" ".0e0" "+.0e0" "-.0e0")
+                     (2 "01" "1ee1" "1e++1")
+                     (3 "-01")
+                     (4 "0.0.0" "1.1.1" "1e1e1")
+                     (5 "-0.0.0" "-1.1.1")))
+      ;; Expected error and point.
+      (let ((res `((json-number-format ,pos) . ,pos)))
+        (dolist (str strings)
+          (should (equal (read str) res)))))))
 
 (ert-deftest test-json-encode-number ()
+  (should (equal (json-encode-number 0) "0"))
+  (should (equal (json-encode-number -0) "0"))
   (should (equal (json-encode-number 3) "3"))
   (should (equal (json-encode-number -5) "-5"))
-  (should (equal (json-encode-number 123.456) "123.456")))
+  (should (equal (json-encode-number 123.456) "123.456"))
+  (let ((bignum (1+ most-positive-fixnum)))
+    (should (equal (json-encode-number bignum)
+                   (number-to-string bignum)))))
 
-;; Strings
+;;; Strings
 
 (ert-deftest test-json-read-escaped-char ()
   (json-tests--with-temp-buffer "\\\""
-    (should (equal (json-read-escaped-char) ?\"))))
+    (should (= (json-read-escaped-char) ?\"))
+    (should (eobp)))
+  (json-tests--with-temp-buffer "\\\\ "
+    (should (= (json-read-escaped-char) ?\\))
+    (should (= (point) (+ (point-min) 2))))
+  (json-tests--with-temp-buffer "\\b "
+    (should (= (json-read-escaped-char) ?\b))
+    (should (= (point) (+ (point-min) 2))))
+  (json-tests--with-temp-buffer "\\f "
+    (should (= (json-read-escaped-char) ?\f))
+    (should (= (point) (+ (point-min) 2))))
+  (json-tests--with-temp-buffer "\\n "
+    (should (= (json-read-escaped-char) ?\n))
+    (should (= (point) (+ (point-min) 2))))
+  (json-tests--with-temp-buffer "\\r "
+    (should (= (json-read-escaped-char) ?\r))
+    (should (= (point) (+ (point-min) 2))))
+  (json-tests--with-temp-buffer "\\t "
+    (should (= (json-read-escaped-char) ?\t))
+    (should (= (point) (+ (point-min) 2))))
+  (json-tests--with-temp-buffer "\\x "
+    (should (= (json-read-escaped-char) ?x))
+    (should (= (point) (+ (point-min) 2))))
+  (json-tests--with-temp-buffer "\\ud800\\uDC00 "
+    (should (= (json-read-escaped-char) #x10000))
+    (should (= (point) (+ (point-min) 12))))
+  (json-tests--with-temp-buffer "\\ud7ff\\udc00 "
+    (should (= (json-read-escaped-char) #xd7ff))
+    (should (= (point) (+ (point-min) 6))))
+  (json-tests--with-temp-buffer "\\uffff "
+    (should (= (json-read-escaped-char) #xffff))
+    (should (= (point) (+ (point-min) 6))))
+  (json-tests--with-temp-buffer "\\ufffff "
+    (should (= (json-read-escaped-char) #xffff))
+    (should (= (point) (+ (point-min) 6)))))
+
+(ert-deftest test-json-read-escaped-char-invalid ()
+  (json-tests--with-temp-buffer ""
+    (should-error (json-read-escaped-char)))
+  (json-tests--with-temp-buffer "\\"
+    (should-error (json-read-escaped-char) :type 'json-end-of-file))
+  (json-tests--with-temp-buffer "\\ufff "
+    (should (equal (should-error (json-read-escaped-char))
+                   (list 'json-string-escape (+ (point-min) 2)))))
+  (json-tests--with-temp-buffer "\\ufffg "
+    (should (equal (should-error (json-read-escaped-char))
+                   (list 'json-string-escape (+ (point-min) 2))))))
 
 (ert-deftest test-json-read-string ()
+  (json-tests--with-temp-buffer ""
+    (should-error (json-read-string)))
   (json-tests--with-temp-buffer "\"formfeed\f\""
-    (should-error (json-read-string) :type 'json-string-format))
+    (should (equal (should-error (json-read-string))
+                   '(json-string-format ?\f))))
+  (json-tests--with-temp-buffer "\"\""
+    (should (equal (json-read-string) "")))
   (json-tests--with-temp-buffer "\"foo \\\"bar\\\"\""
     (should (equal (json-read-string) "foo \"bar\"")))
   (json-tests--with-temp-buffer "\"abcαβγ\""
@@ -175,57 +405,117 @@ Point is moved to beginning of the buffer."
   ;; Bug#24784
   (json-tests--with-temp-buffer "\"\\uD834\\uDD1E\""
     (should (equal (json-read-string) "\U0001D11E")))
+  (json-tests--with-temp-buffer "f"
+    (should-error (json-read-string) :type 'json-end-of-file))
   (json-tests--with-temp-buffer "foo"
-    (should-error (json-read-string) :type 'json-string-format)))
+    (should-error (json-read-string) :type 'json-end-of-file)))
 
 (ert-deftest test-json-encode-string ()
+  (should (equal (json-encode-string "") "\"\""))
+  (should (equal (json-encode-string "a") "\"a\""))
   (should (equal (json-encode-string "foo") "\"foo\""))
   (should (equal (json-encode-string "a\n\fb") "\"a\\n\\fb\""))
   (should (equal (json-encode-string "\nasdфыв\u001f\u007ffgh\t")
                  "\"\\nasdфыв\\u001f\u007ffgh\\t\"")))
 
 (ert-deftest test-json-encode-key ()
+  (should (equal (json-encode-key "") "\"\""))
+  (should (equal (json-encode-key '##) "\"\""))
+  (should (equal (json-encode-key :) "\"\""))
   (should (equal (json-encode-key "foo") "\"foo\""))
   (should (equal (json-encode-key 'foo) "\"foo\""))
   (should (equal (json-encode-key :foo) "\"foo\""))
-  (should-error (json-encode-key 5) :type 'json-key-format)
-  (should-error (json-encode-key ["foo"]) :type 'json-key-format)
-  (should-error (json-encode-key '("foo")) :type 'json-key-format))
+  (should (equal (should-error (json-encode-key 5))
+                 '(json-key-format 5)))
+  (should (equal (should-error (json-encode-key ["foo"]))
+                 '(json-key-format ["foo"])))
+  (should (equal (should-error (json-encode-key '("foo")))
+                 '(json-key-format ("foo")))))
 
 ;;; Objects
 
 (ert-deftest test-json-new-object ()
   (let ((json-object-type 'alist))
-    (should (equal (json-new-object) '())))
+    (should-not (json-new-object)))
   (let ((json-object-type 'plist))
-    (should (equal (json-new-object) '())))
+    (should-not (json-new-object)))
   (let* ((json-object-type 'hash-table)
          (json-object (json-new-object)))
     (should (hash-table-p json-object))
-    (should (= (hash-table-count json-object) 0))))
+    (should (map-empty-p json-object))
+    (should (eq (hash-table-test json-object) #'equal))))
 
-(ert-deftest test-json-add-to-object ()
+(ert-deftest test-json-add-to-alist ()
   (let* ((json-object-type 'alist)
-         (json-key-type nil)
          (obj (json-new-object)))
-    (setq obj (json-add-to-object obj "a" 1))
-    (setq obj (json-add-to-object obj "b" 2))
-    (should (equal (assq 'a obj) '(a . 1)))
-    (should (equal (assq 'b obj) '(b . 2))))
+    (let ((json-key-type nil))
+      (setq obj (json-add-to-object obj "a" 1))
+      (setq obj (json-add-to-object obj "b" 2))
+      (should (equal (assq 'a obj) '(a . 1)))
+      (should (equal (assq 'b obj) '(b . 2))))
+    (let ((json-key-type 'symbol))
+      (setq obj (json-add-to-object obj "c" 3))
+      (setq obj (json-add-to-object obj "d" 4))
+      (should (equal (assq 'c obj) '(c . 3)))
+      (should (equal (assq 'd obj) '(d . 4))))
+    (let ((json-key-type 'keyword))
+      (setq obj (json-add-to-object obj "e" 5))
+      (setq obj (json-add-to-object obj "f" 6))
+      (should (equal (assq :e obj) '(:e . 5)))
+      (should (equal (assq :f obj) '(:f . 6))))
+    (let ((json-key-type 'string))
+      (setq obj (json-add-to-object obj "g" 7))
+      (setq obj (json-add-to-object obj "h" 8))
+      (should (equal (assoc "g" obj) '("g" . 7)))
+      (should (equal (assoc "h" obj) '("h" . 8))))))
+
+(ert-deftest test-json-add-to-plist ()
   (let* ((json-object-type 'plist)
-         (json-key-type nil)
          (obj (json-new-object)))
-    (setq obj (json-add-to-object obj "a" 1))
-    (setq obj (json-add-to-object obj "b" 2))
-    (should (= (plist-get obj :a) 1))
-    (should (= (plist-get obj :b) 2)))
+    (let ((json-key-type nil))
+      (setq obj (json-add-to-object obj "a" 1))
+      (setq obj (json-add-to-object obj "b" 2))
+      (should (= (plist-get obj :a) 1))
+      (should (= (plist-get obj :b) 2)))
+    (let ((json-key-type 'keyword))
+      (setq obj (json-add-to-object obj "c" 3))
+      (setq obj (json-add-to-object obj "d" 4))
+      (should (= (plist-get obj :c) 3))
+      (should (= (plist-get obj :d) 4)))
+    (let ((json-key-type 'symbol))
+      (setq obj (json-add-to-object obj "e" 5))
+      (setq obj (json-add-to-object obj "f" 6))
+      (should (= (plist-get obj 'e) 5))
+      (should (= (plist-get obj 'f) 6)))
+    (let ((json-key-type 'string))
+      (setq obj (json-add-to-object obj "g" 7))
+      (setq obj (json-add-to-object obj "h" 8))
+      (should (= (lax-plist-get obj "g") 7))
+      (should (= (lax-plist-get obj "h") 8)))))
+
+(ert-deftest test-json-add-to-hash-table ()
   (let* ((json-object-type 'hash-table)
-         (json-key-type nil)
          (obj (json-new-object)))
-    (setq obj (json-add-to-object obj "a" 1))
-    (setq obj (json-add-to-object obj "b" 2))
-    (should (= (gethash "a" obj) 1))
-    (should (= (gethash "b" obj) 2))))
+    (let ((json-key-type nil))
+      (setq obj (json-add-to-object obj "a" 1))
+      (setq obj (json-add-to-object obj "b" 2))
+      (should (= (gethash "a" obj) 1))
+      (should (= (gethash "b" obj) 2)))
+    (let ((json-key-type 'string))
+      (setq obj (json-add-to-object obj "c" 3))
+      (setq obj (json-add-to-object obj "d" 4))
+      (should (= (gethash "c" obj) 3))
+      (should (= (gethash "d" obj) 4)))
+    (let ((json-key-type 'symbol))
+      (setq obj (json-add-to-object obj "e" 5))
+      (setq obj (json-add-to-object obj "f" 6))
+      (should (= (gethash 'e obj) 5))
+      (should (= (gethash 'f obj) 6)))
+    (let ((json-key-type 'keyword))
+      (setq obj (json-add-to-object obj "g" 7))
+      (setq obj (json-add-to-object obj "h" 8))
+      (should (= (gethash :g obj) 7))
+      (should (= (gethash :h obj) 8)))))
 
 (ert-deftest test-json-read-object ()
   (json-tests--with-temp-buffer "{ \"a\": 1, \"b\": 2 }"
@@ -238,94 +528,384 @@ Point is moved to beginning of the buffer."
     (let* ((json-object-type 'hash-table)
            (hash-table (json-read-object)))
       (should (= (gethash "a" hash-table) 1))
-      (should (= (gethash "b" hash-table) 2))))
+      (should (= (gethash "b" hash-table) 2)))))
+
+(ert-deftest test-json-read-object-empty ()
+  (json-tests--with-temp-buffer "{}"
+    (let ((json-object-type 'alist))
+      (should-not (save-excursion (json-read-object))))
+    (let ((json-object-type 'plist))
+      (should-not (save-excursion (json-read-object))))
+    (let* ((json-object-type 'hash-table)
+           (hash-table (json-read-object)))
+      (should (hash-table-p hash-table))
+      (should (map-empty-p hash-table)))))
+
+(ert-deftest test-json-read-object-invalid ()
+  (json-tests--with-temp-buffer "{ \"a\" 1, \"b\": 2 }"
+    (should (equal (should-error (json-read-object))
+                   '(json-object-format ":" ?1))))
   (json-tests--with-temp-buffer "{ \"a\": 1 \"b\": 2 }"
-    (should-error (json-read-object) :type 'json-object-format)))
+    (should (equal (should-error (json-read-object))
+                   '(json-object-format "," ?\")))))
+
+(ert-deftest test-json-read-object-function ()
+  (let* ((pre nil)
+         (post nil)
+         (keys '("b" "a"))
+         (json-pre-element-read-function
+          (lambda (key)
+            (setq pre 'pre)
+            (should (equal key (pop keys)))))
+         (json-post-element-read-function
+          (lambda () (setq post 'post))))
+    (json-tests--with-temp-buffer "{ \"b\": 2, \"a\": 1 }"
+      (json-read-object)
+      (should (eq pre 'pre))
+      (should (eq post 'post)))))
 
 (ert-deftest test-json-encode-hash-table ()
-  (let ((hash-table (make-hash-table))
-        (json-encoding-object-sort-predicate 'string<)
+  (let ((json-encoding-object-sort-predicate nil)
         (json-encoding-pretty-print nil))
-    (puthash :a 1 hash-table)
-    (puthash :b 2 hash-table)
-    (puthash :c 3 hash-table)
-    (should (equal (json-encode hash-table)
-                   "{\"a\":1,\"b\":2,\"c\":3}"))))
-
-(ert-deftest json-encode-simple-alist ()
-  (let ((json-encoding-pretty-print nil))
-    (should (equal (json-encode '((a . 1) (b . 2)))
-                   "{\"a\":1,\"b\":2}"))))
-
-(ert-deftest test-json-encode-plist ()
-  (let ((plist '(:a 1 :b 2))
+    (should (equal (json-encode-hash-table #s(hash-table)) "{}"))
+    (should (equal (json-encode-hash-table #s(hash-table data (a 1)))
+                   "{\"a\":1}"))
+    (should (member (json-encode-hash-table #s(hash-table data (b 2 a 1)))
+                    '("{\"a\":1,\"b\":2}" "{\"b\":2,\"a\":1}")))
+    (should (member (json-encode-hash-table #s(hash-table data (c 3 b 2 a 1)))
+                    '("{\"a\":1,\"b\":2,\"c\":3}"
+                      "{\"a\":1,\"c\":3,\"b\":2}"
+                      "{\"b\":2,\"a\":1,\"c\":3}"
+                      "{\"b\":2,\"c\":3,\"a\":1}"
+                      "{\"c\":3,\"a\":1,\"b\":2}"
+                      "{\"c\":3,\"b\":2,\"a\":1}")))))
+
+(ert-deftest test-json-encode-hash-table-pretty ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings nil))
+    (should (equal (json-encode-hash-table #s(hash-table)) "{}"))
+    (should (equal (json-encode-hash-table #s(hash-table data (a 1)))
+                   "{\n \"a\": 1\n}"))
+    (should (member (json-encode-hash-table #s(hash-table data (b 2 a 1)))
+                    '("{\n \"a\": 1,\n \"b\": 2\n}"
+                      "{\n \"b\": 2,\n \"a\": 1\n}")))
+    (should (member (json-encode-hash-table #s(hash-table data (c 3 b 2 a 1)))
+                    '("{\n \"a\": 1,\n \"b\": 2,\n \"c\": 3\n}"
+                      "{\n \"a\": 1,\n \"c\": 3,\n \"b\": 2\n}"
+                      "{\n \"b\": 2,\n \"a\": 1,\n \"c\": 3\n}"
+                      "{\n \"b\": 2,\n \"c\": 3,\n \"a\": 1\n}"
+                      "{\n \"c\": 3,\n \"a\": 1,\n \"b\": 2\n}"
+                      "{\n \"c\": 3,\n \"b\": 2,\n \"a\": 1\n}")))))
+
+(ert-deftest test-json-encode-hash-table-lisp-style ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings t))
+    (should (equal (json-encode-hash-table #s(hash-table)) "{}"))
+    (should (equal (json-encode-hash-table #s(hash-table data (a 1)))
+                   "{\n \"a\": 1}"))
+    (should (member (json-encode-hash-table #s(hash-table data (b 2 a 1)))
+                    '("{\n \"a\": 1,\n \"b\": 2}"
+                      "{\n \"b\": 2,\n \"a\": 1}")))
+    (should (member (json-encode-hash-table #s(hash-table data (c 3 b 2 a 1)))
+                    '("{\n \"a\": 1,\n \"b\": 2,\n \"c\": 3}"
+                      "{\n \"a\": 1,\n \"c\": 3,\n \"b\": 2}"
+                      "{\n \"b\": 2,\n \"a\": 1,\n \"c\": 3}"
+                      "{\n \"b\": 2,\n \"c\": 3,\n \"a\": 1}"
+                      "{\n \"c\": 3,\n \"a\": 1,\n \"b\": 2}"
+                      "{\n \"c\": 3,\n \"b\": 2,\n \"a\": 1}")))))
+
+(ert-deftest test-json-encode-hash-table-sort ()
+  (let ((json-encoding-object-sort-predicate #'string<)
         (json-encoding-pretty-print nil))
-    (should (equal (json-encode plist) "{\"a\":1,\"b\":2}"))))
-
-(ert-deftest test-json-encode-plist-with-sort-predicate ()
-  (let ((plist '(:c 3 :a 1 :b 2))
-        (json-encoding-object-sort-predicate 'string<)
+    (pcase-dolist (`(,in . ,out)
+                   '((#s(hash-table) . "{}")
+                     (#s(hash-table data (a 1)) . "{\"a\":1}")
+                     (#s(hash-table data (b 2 a 1)) . "{\"a\":1,\"b\":2}")
+                     (#s(hash-table data (c 3 b 2 a 1))
+                        . "{\"a\":1,\"b\":2,\"c\":3}")))
+      (let ((copy (map-pairs in)))
+        (should (equal (json-encode-hash-table in) out))
+        ;; Ensure sorting isn't destructive.
+        (should (seq-set-equal-p (map-pairs in) copy))))))
+
+(ert-deftest test-json-encode-alist ()
+  (let ((json-encoding-object-sort-predicate nil)
         (json-encoding-pretty-print nil))
-    (should (equal (json-encode plist) "{\"a\":1,\"b\":2,\"c\":3}"))))
+    (should (equal (json-encode-alist ()) "{}"))
+    (should (equal (json-encode-alist '((a . 1))) "{\"a\":1}"))
+    (should (equal (json-encode-alist '((b . 2) (a . 1))) "{\"b\":2,\"a\":1}"))
+    (should (equal (json-encode-alist '((c . 3) (b . 2) (a . 1)))
+                   "{\"c\":3,\"b\":2,\"a\":1}"))))
+
+(ert-deftest test-json-encode-alist-pretty ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings nil))
+    (should (equal (json-encode-alist ()) "{}"))
+    (should (equal (json-encode-alist '((a . 1))) "{\n \"a\": 1\n}"))
+    (should (equal (json-encode-alist '((b . 2) (a . 1)))
+                   "{\n \"b\": 2,\n \"a\": 1\n}"))
+    (should (equal (json-encode-alist '((c . 3) (b . 2) (a . 1)))
+                   "{\n \"c\": 3,\n \"b\": 2,\n \"a\": 1\n}"))))
+
+(ert-deftest test-json-encode-alist-lisp-style ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings t))
+    (should (equal (json-encode-alist ()) "{}"))
+    (should (equal (json-encode-alist '((a . 1))) "{\n \"a\": 1}"))
+    (should (equal (json-encode-alist '((b . 2) (a . 1)))
+                   "{\n \"b\": 2,\n \"a\": 1}"))
+    (should (equal (json-encode-alist '((c . 3) (b . 2) (a . 1)))
+                   "{\n \"c\": 3,\n \"b\": 2,\n \"a\": 1}"))))
+
+(ert-deftest test-json-encode-alist-sort ()
+  (let ((json-encoding-object-sort-predicate #'string<)
+        (json-encoding-pretty-print nil))
+    (pcase-dolist (`(,in . ,out)
+                   '((() . "{}")
+                     (((a . 1)) . "{\"a\":1}")
+                     (((b . 2) (a . 1)) . "{\"a\":1,\"b\":2}")
+                     (((c . 3) (b . 2) (a . 1))
+                      . "{\"a\":1,\"b\":2,\"c\":3}")))
+      (let ((copy (copy-alist in)))
+        (should (equal (json-encode-alist in) out))
+        ;; Ensure sorting isn't destructive (bug#40693).
+        (should (equal in copy))))))
 
-(ert-deftest test-json-encode-alist-with-sort-predicate ()
-  (let ((alist '((:c . 3) (:a . 1) (:b . 2)))
-        (json-encoding-object-sort-predicate 'string<)
+(ert-deftest test-json-encode-plist ()
+  (let ((json-encoding-object-sort-predicate nil)
         (json-encoding-pretty-print nil))
-    (should (equal (json-encode alist) "{\"a\":1,\"b\":2,\"c\":3}"))))
+    (should (equal (json-encode-plist ()) "{}"))
+    (should (equal (json-encode-plist '(:a 1)) "{\"a\":1}"))
+    (should (equal (json-encode-plist '(:b 2 :a 1)) "{\"b\":2,\"a\":1}"))
+    (should (equal (json-encode-plist '(:c 3 :b 2 :a 1))
+                   "{\"c\":3,\"b\":2,\"a\":1}"))))
+
+(ert-deftest test-json-encode-plist-pretty ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings nil))
+    (should (equal (json-encode-plist ()) "{}"))
+    (should (equal (json-encode-plist '(:a 1)) "{\n \"a\": 1\n}"))
+    (should (equal (json-encode-plist '(:b 2 :a 1))
+                   "{\n \"b\": 2,\n \"a\": 1\n}"))
+    (should (equal (json-encode-plist '(:c 3 :b 2 :a 1))
+                   "{\n \"c\": 3,\n \"b\": 2,\n \"a\": 1\n}"))))
+
+(ert-deftest test-json-encode-plist-lisp-style ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings t))
+    (should (equal (json-encode-plist ()) "{}"))
+    (should (equal (json-encode-plist '(:a 1)) "{\n \"a\": 1}"))
+    (should (equal (json-encode-plist '(:b 2 :a 1))
+                   "{\n \"b\": 2,\n \"a\": 1}"))
+    (should (equal (json-encode-plist '(:c 3 :b 2 :a 1))
+                   "{\n \"c\": 3,\n \"b\": 2,\n \"a\": 1}"))))
+
+(ert-deftest test-json-encode-plist-sort ()
+  (let ((json-encoding-object-sort-predicate #'string<)
+        (json-encoding-pretty-print nil))
+    (pcase-dolist (`(,in . ,out)
+                   '((() . "{}")
+                     ((:a 1) . "{\"a\":1}")
+                     ((:b 2 :a 1) . "{\"a\":1,\"b\":2}")
+                     ((:c 3 :b 2 :a 1) . "{\"a\":1,\"b\":2,\"c\":3}")))
+      (let ((copy (copy-sequence in)))
+        (should (equal (json-encode-plist in) out))
+        ;; Ensure sorting isn't destructive.
+        (should (equal in copy))))))
 
 (ert-deftest test-json-encode-list ()
-  (let ((json-encoding-pretty-print nil))
-    (should (equal (json-encode-list '(:a 1 :b 2))
-                   "{\"a\":1,\"b\":2}"))
-    (should (equal (json-encode-list '((:a . 1) (:b . 2)))
-                   "{\"a\":1,\"b\":2}"))
-    (should (equal (json-encode-list '(1 2 3 4)) "[1,2,3,4]"))))
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print nil))
+    (should (equal (json-encode-list ()) "{}"))
+    (should (equal (json-encode-list '(a)) "[\"a\"]"))
+    (should (equal (json-encode-list '(:a)) "[\"a\"]"))
+    (should (equal (json-encode-list '("a")) "[\"a\"]"))
+    (should (equal (json-encode-list '(a 1)) "[\"a\",1]"))
+    (should (equal (json-encode-list '("a" 1)) "[\"a\",1]"))
+    (should (equal (json-encode-list '(:a 1)) "{\"a\":1}"))
+    (should (equal (json-encode-list '((a . 1))) "{\"a\":1}"))
+    (should (equal (json-encode-list '((:a . 1))) "{\"a\":1}"))
+    (should (equal (json-encode-list '(:b 2 :a)) "[\"b\",2,\"a\"]"))
+    (should (equal (json-encode-list '(4 3 2 1)) "[4,3,2,1]"))
+    (should (equal (json-encode-list '(b 2 a 1)) "[\"b\",2,\"a\",1]"))
+    (should (equal (json-encode-list '(:b 2 :a 1)) "{\"b\":2,\"a\":1}"))
+    (should (equal (json-encode-list '((b . 2) (a . 1))) "{\"b\":2,\"a\":1}"))
+    (should (equal (json-encode-list '((:b . 2) (:a . 1)))
+                   "{\"b\":2,\"a\":1}"))
+    (should (equal (json-encode-list '((a) 1)) "[[\"a\"],1]"))
+    (should (equal (json-encode-list '((:a) 1)) "[[\"a\"],1]"))
+    (should (equal (json-encode-list '(("a") 1)) "[[\"a\"],1]"))
+    (should (equal (json-encode-list '((a 1) 2)) "[[\"a\",1],2]"))
+    (should (equal (json-encode-list '((:a 1) 2)) "[{\"a\":1},2]"))
+    (should (equal (json-encode-list '(((a . 1)) 2)) "[{\"a\":1},2]"))
+    (should (equal (json-encode-list '(:a 1 :b (2))) "{\"a\":1,\"b\":[2]}"))
+    (should (equal (json-encode-list '((a . 1) (b 2))) "{\"a\":1,\"b\":[2]}"))
+    (should-error (json-encode-list '(a . 1)) :type 'wrong-type-argument)
+    (should-error (json-encode-list '((a . 1) 2)) :type 'wrong-type-argument)
+    (should (equal (should-error (json-encode-list []))
+                   '(json-error [])))
+    (should (equal (should-error (json-encode-list [a]))
+                   '(json-error [a])))))
 
 ;;; Arrays
 
 (ert-deftest test-json-read-array ()
   (let ((json-array-type 'vector))
+    (json-tests--with-temp-buffer "[]"
+      (should (equal (json-read-array) [])))
+    (json-tests--with-temp-buffer "[ ]"
+      (should (equal (json-read-array) [])))
+    (json-tests--with-temp-buffer "[1]"
+      (should (equal (json-read-array) [1])))
     (json-tests--with-temp-buffer "[1, 2, \"a\", \"b\"]"
       (should (equal (json-read-array) [1 2 "a" "b"]))))
   (let ((json-array-type 'list))
+    (json-tests--with-temp-buffer "[]"
+      (should-not (json-read-array)))
+    (json-tests--with-temp-buffer "[ ]"
+      (should-not (json-read-array)))
+    (json-tests--with-temp-buffer "[1]"
+      (should (equal (json-read-array) '(1))))
     (json-tests--with-temp-buffer "[1, 2, \"a\", \"b\"]"
       (should (equal (json-read-array) '(1 2 "a" "b")))))
   (json-tests--with-temp-buffer "[1 2]"
-    (should-error (json-read-array) :type 'json-error)))
+    (should (equal (should-error (json-read-array))
+                   '(json-array-format "," ?2)))))
+
+(ert-deftest test-json-read-array-function ()
+  (let* ((pre nil)
+         (post nil)
+         (keys '(0 1))
+         (json-pre-element-read-function
+          (lambda (key)
+            (setq pre 'pre)
+            (should (equal key (pop keys)))))
+         (json-post-element-read-function
+          (lambda () (setq post 'post))))
+    (json-tests--with-temp-buffer "[1, 0]"
+      (json-read-array)
+      (should (eq pre 'pre))
+      (should (eq post 'post)))))
 
 (ert-deftest test-json-encode-array ()
-  (let ((json-encoding-pretty-print nil))
-    (should (equal (json-encode-array [1 2 "a" "b"])
-                   "[1,2,\"a\",\"b\"]"))))
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print nil))
+    (should (equal (json-encode-array ()) "[]"))
+    (should (equal (json-encode-array []) "[]"))
+    (should (equal (json-encode-array '(1)) "[1]"))
+    (should (equal (json-encode-array '[1]) "[1]"))
+    (should (equal (json-encode-array '(2 1)) "[2,1]"))
+    (should (equal (json-encode-array '[2 1]) "[2,1]"))
+    (should (equal (json-encode-array '[:b a 2 1]) "[\"b\",\"a\",2,1]"))))
+
+(ert-deftest test-json-encode-array-pretty ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings nil))
+    (should (equal (json-encode-array ()) "[]"))
+    (should (equal (json-encode-array []) "[]"))
+    (should (equal (json-encode-array '(1)) "[\n 1\n]"))
+    (should (equal (json-encode-array '[1]) "[\n 1\n]"))
+    (should (equal (json-encode-array '(2 1)) "[\n 2,\n 1\n]"))
+    (should (equal (json-encode-array '[2 1]) "[\n 2,\n 1\n]"))
+    (should (equal (json-encode-array '[:b a 2 1])
+                   "[\n \"b\",\n \"a\",\n 2,\n 1\n]"))))
+
+(ert-deftest test-json-encode-array-lisp-style ()
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print t)
+        (json-encoding-default-indentation " ")
+        (json-encoding-lisp-style-closings t))
+    (should (equal (json-encode-array ()) "[]"))
+    (should (equal (json-encode-array []) "[]"))
+    (should (equal (json-encode-array '(1)) "[\n 1]"))
+    (should (equal (json-encode-array '[1]) "[\n 1]"))
+    (should (equal (json-encode-array '(2 1)) "[\n 2,\n 1]"))
+    (should (equal (json-encode-array '[2 1]) "[\n 2,\n 1]"))
+    (should (equal (json-encode-array '[:b a 2 1])
+                   "[\n \"b\",\n \"a\",\n 2,\n 1]"))))
 
 ;;; Reader
 
 (ert-deftest test-json-read ()
-  (json-tests--with-temp-buffer "{ \"a\": 1 }"
-    ;; We don't care exactly what the return value is (that is tested
-    ;; in `test-json-read-object'), but it should parse without error.
-    (should (json-read)))
+  (pcase-dolist (`(,fn . ,contents)
+                 '((json-read-string  "\"\"" "\"a\"")
+                   (json-read-array   "[]" "[1]")
+                   (json-read-object  "{}" "{\"a\":1}")
+                   (json-read-keyword "null" "false" "true")
+                   (json-read-number
+                    "-0" "0" "1" "2" "3" "4" "5" "6" "7" "8" "9")))
+    (dolist (content contents)
+      ;; Check that leading whitespace is skipped.
+      (dolist (str (list content (concat " " content)))
+        (cl-letf* ((called nil)
+                   ((symbol-function fn)
+                    (lambda (&rest _) (setq called t))))
+          (json-tests--with-temp-buffer str
+            ;; We don't care exactly what the return value is (that is
+            ;; tested elsewhere), but it should parse without error.
+            (should (json-read))
+            (should called)))))))
+
+(ert-deftest test-json-read-invalid ()
   (json-tests--with-temp-buffer ""
     (should-error (json-read) :type 'json-end-of-file))
-  (json-tests--with-temp-buffer "xxx"
-    (let ((err (should-error (json-read) :type 'json-readtable-error)))
-      (should (equal (cdr err) '(?x))))))
+  (json-tests--with-temp-buffer " "
+    (should-error (json-read) :type 'json-end-of-file))
+  (json-tests--with-temp-buffer "x"
+    (should (equal (should-error (json-read))
+                  '(json-readtable-error ?x))))
+  (json-tests--with-temp-buffer " x"
+    (should (equal (should-error (json-read))
+                  '(json-readtable-error ?x)))))
 
 (ert-deftest test-json-read-from-string ()
-  (let ((json-string "{ \"a\": 1 }"))
-    (json-tests--with-temp-buffer json-string
-      (should (equal (json-read-from-string json-string)
+  (dolist (str '("\"\"" "\"a\"" "[]" "[1]" "{}" "{\"a\":1}"
+                 "null" "false" "true" "0" "123"))
+    (json-tests--with-temp-buffer str
+      (should (equal (json-read-from-string str)
                      (json-read))))))
 
-;;; JSON encoder
+;;; Encoder
 
 (ert-deftest test-json-encode ()
+  (should (equal (json-encode t) "true"))
+  (let ((json-null 'null))
+    (should (equal (json-encode json-null) "null")))
+  (let ((json-false 'false))
+    (should (equal (json-encode json-false) "false")))
+  (should (equal (json-encode "") "\"\""))
   (should (equal (json-encode "foo") "\"foo\""))
+  (should (equal (json-encode :) "\"\""))
+  (should (equal (json-encode :foo) "\"foo\""))
+  (should (equal (json-encode '(1)) "[1]"))
+  (should (equal (json-encode 'foo) "\"foo\""))
+  (should (equal (json-encode 0) "0"))
+  (should (equal (json-encode 123) "123"))
+  (let ((json-encoding-object-sort-predicate nil)
+        (json-encoding-pretty-print nil))
+    (should (equal (json-encode []) "[]"))
+    (should (equal (json-encode [1]) "[1]"))
+    (should (equal (json-encode #s(hash-table)) "{}"))
+    (should (equal (json-encode #s(hash-table data (a 1))) "{\"a\":1}")))
   (with-temp-buffer
-    (should-error (json-encode (current-buffer)) :type 'json-error)))
+    (should (equal (should-error (json-encode (current-buffer)))
+                   (list 'json-error (current-buffer))))))
 
-;;; Pretty-print
+;;; Pretty printing & minimizing
 
 (defun json-tests-equal-pretty-print (original &optional expected)
   "Abort current test if pretty-printing ORIGINAL does not yield EXPECTED.
@@ -351,46 +931,45 @@ nil, ORIGINAL should stay unchanged by pretty-printing."
   (json-tests-equal-pretty-print "0.123"))
 
 (ert-deftest test-json-pretty-print-object ()
-  ;; empty (regression test for bug#24252)
-  (json-tests-equal-pretty-print
-   "{}"
-   "{\n}")
-  ;; one pair
+  ;; Empty (regression test for bug#24252).
+  (json-tests-equal-pretty-print "{}")
+  ;; One pair.
   (json-tests-equal-pretty-print
    "{\"key\":1}"
    "{\n  \"key\": 1\n}")
-  ;; two pairs
+  ;; Two pairs.
   (json-tests-equal-pretty-print
    "{\"key1\":1,\"key2\":2}"
    "{\n  \"key1\": 1,\n  \"key2\": 2\n}")
-  ;; embedded object
+  ;; Nested object.
   (json-tests-equal-pretty-print
    "{\"foo\":{\"key\":1}}"
    "{\n  \"foo\": {\n    \"key\": 1\n  }\n}")
-  ;; embedded array
+  ;; Nested array.
   (json-tests-equal-pretty-print
    "{\"key\":[1,2]}"
    "{\n  \"key\": [\n    1,\n    2\n  ]\n}"))
 
 (ert-deftest test-json-pretty-print-array ()
-  ;; empty
+  ;; Empty.
   (json-tests-equal-pretty-print "[]")
-  ;; one item
+  ;; One item.
   (json-tests-equal-pretty-print
    "[1]"
    "[\n  1\n]")
-  ;; two items
+  ;; Two items.
   (json-tests-equal-pretty-print
    "[1,2]"
    "[\n  1,\n  2\n]")
-  ;; embedded object
+  ;; Nested object.
   (json-tests-equal-pretty-print
    "[{\"key\":1}]"
    "[\n  {\n    \"key\": 1\n  }\n]")
-  ;; embedded array
+  ;; Nested array.
   (json-tests-equal-pretty-print
    "[[1,2]]"
    "[\n  [\n    1,\n    2\n  ]\n]"))
 
 (provide 'json-tests)
+
 ;;; json-tests.el ends here