scratch/icons 6ad07cd620 01/11: New library icons.el adds support for icon sets

[Stefan Kangas]

branch: scratch/icons
commit 6ad07cd6200dad5e1eb35bac9f5b7c35925e80f8
Author: Stefan Kangas <stefan@marxist.se>
Commit: Stefan Kangas <stefankangas@gmail.com>

    New library icons.el adds support for icon sets
    
    * lisp/icons.el:
    * test/lisp/icons-tests.el: New files.
    * test/lisp/icons-resources/*: New resource files for tests.
---
 lisp/skicons.el                      | 859 +++++++++++++++++++++++++++++++++++
 test/lisp/icons-resources/apple.pbm  |   0
 test/lisp/icons-resources/apple.svg  |   0
 test/lisp/icons-resources/apple.xpm  |   0
 test/lisp/icons-resources/apple2.svg |   0
 test/lisp/icons-resources/lemon.svg  |   0
 test/lisp/icons-resources/orange.svg |   0
 test/lisp/icons-tests.el             | 131 ++++++
 8 files changed, 990 insertions(+)

diff --git a/lisp/skicons.el b/lisp/skicons.el
new file mode 100644
index 0000000000..bce7c904eb
--- /dev/null
+++ b/lisp/skicons.el
@@ -0,0 +1,859 @@
+;;; icons.el --- Icon support in buffers, mode-line, etc.  -*- 
lexical-binding: t -*-
+
+;; Copyright (C) 2022 Free Software Foundation, Inc.
+
+;; Author: Stefan Kangas <stefan@marxist.se>
+;; Keywords: faces, multimedia
+
+;; This file is part of GNU Emacs.
+
+;; 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Commentary:
+
+;; * Introduction
+;;
+;; This library provides support for icons, that can be used for
+;; things like decorating a buffer, toolbar buttons or the mode-line.
+;; Emacs comes bundled with several sets of icons, but you can also
+;; install new sets from package archives like GNU ELPA.
+;;
+;; icons.el allows users to change the appearance of icons all over
+;; Emacs, in libraries supporting it, by customizing
+;; `icons-set-priority'.  You can think of this as icon themes for
+;; Emacs.
+;;
+;; Run `M-x customize-group RET icons RET' to see all user options.
+;;
+;; * Using this library as an Emacs Lisp developer
+;;
+;; To use these icons from Lisp, see `icons-get' and `icons-insert'.
+;; To use an icon in the modeline, use `icons-get-for-modeline'.
+;; Type `M-x list-icons' to see a list of all supported icons.
+;;
+;; * Adding Icon sets
+;;
+;; If you want to add a new icon set, the best starting point is to
+;; study an existing icon set.  It comes down to one file containing a
+;; `icons-define-set' form, and then the actual image files.  It is
+;; highly recommended to use SVG icons, but consider providing XPM and
+;; PBM fall-backs for users on older machines.
+;;
+;; To add SVG icons, you need to make sure that the SVG files don't
+;; contain any unnecessary or incorrect markup that stops them from
+;; being displayed correctly.
+;;
+;; There is optional support for more than one size of the same
+;; icon. This is to avoid icons looking bad when resized, and adapt
+;; things like line thickness for display at various sizes.  See also
+;; the explanation on this page:
+;; 
https://github.com/primer/octicons/blob/main/docs/content/guidelines/usage.mdx#sizing
+;;
+;; If you intend to distribute your icon set to others, it is
+;; important that they have a license that allows it.  We cannot give
+;; legal advice, but typically this means a GPL compatible license.
+;; You can find more information about licenses here:
+;; https://www.gnu.org/licenses/license-list.html
+
+;;; Code:
+
+;; TODO:
+;; - UTF-8 icons
+;; - Icon aliases
+
+(require 'cl-lib)
+
+
+;;;; User options.
+
+(defgroup icons nil
+  "Graphical icons in Emacs."
+  :group 'multimedia
+  :version "29.1")
+
+(defcustom icons-enabled (display-graphic-p)
+  "If non-nil, enable graphical icons."
+  :type 'boolean
+  :version "29.1")
+
+(defcustom icons-set-priority '(octicons)
+  "Priority of icon sets used by `icons-insert' et al."
+  :type '(list symbol)
+  :version "29.1")
+
+(defconst icons-type-priority '(svg png ppm xpm pbm)
+  "Priority of icon formats used by `icons-insert' et al.")
+
+
+;;;; Data.
+
+;; FIXME: Is this needed?
+(defvar icons-defined-sets nil
+  "List of all icon sets defined with `icons-define-set'.")
+
+(defvar icons-alist nil
+  "Alist containing all icon sets defined by `icons-define-set'.
+Has the form (NAME . ICONS), where NAME is a symbol representing
+a particular icon, and ICONS is a list of `icons-icon'
+structures.
+
+Note that the list of icons might belong to different defined
+sets of icons, and which one is used depends on the user
+option `icons-set-priority' and `icons-type-priority'.")
+
+(cl-defstruct (icons-icon (:constructor icons-icon-create)
+                     (:copier icons-icon-copy))
+  "Structure containing information about an individual icon file."
+  ( filename nil
+    :documentation "Filename of this icon (string)."
+    :type string)
+  ( type nil
+    :documentation "Image type of the icon (symbol)."
+    :type symbol)
+  ( size nil
+    :documentation "Size of this icon in pixels (integer).
+Specifies the size at which this icon is best viewed."
+    :type integer)
+  ( set nil
+    :documentation "Icon set that this icon belongs to (symbol)."
+    :type symbol))
+
+(defun icons-add-icon (name icon)
+  "Add `icons-icon' ICON with NAME to `icons-alist'."
+  (unless (icons-icon-p icon)
+    (error "Not an icon: %S" icon))
+  (if-let ((orig (cdr (assoc name icons-alist))))
+      (setf (cdr (assoc name icons-alist)) (cons icon orig))
+    (push (cons name (list icon)) icons-alist)))
+
+(defun icons--remove-set (set)
+  "Remove all icons belonging to SET from `icons-alist'."
+  (setq icons-alist
+        (seq-filter
+         (lambda (elem) (> (length elem) 1))
+         (mapcar (lambda (is)
+                   (append
+                    (list (car is))
+                    (seq-filter (lambda (i)
+                                  (not (eq (icons-icon-set i) set)))
+                                (cdr is))))
+                 icons-alist))))
+
+(defun icons-define-set (set icons)
+  "Define a new icon SET from ICONS and add it to `icons-alist'.
+SET is a symbol naming the new set.
+
+ICONS is a list on the form (NAME FILE SIZE) where NAME is the
+name of the icon (a string), FILE is a filename, and SIZE is the
+pixel size at which this is best viewed."
+  (declare (indent defun))
+  (icons--remove-set set)
+  (cl-pushnew set icons-defined-sets)
+  (dolist (icon icons)
+    (let* ((name (car icon))
+           (filename (cadr icon))
+           (size (caddr icon))
+           ;; Infer the type from the filename.
+           (type (intern
+                  (progn
+                    (string-match (rx "." (group (+ alnum)) eos)
+                                  filename)
+                    (match-string 1 filename)))))
+      (icons-add-icon name (icons-icon-create :filename filename
+                                    :size size
+                                    :type type
+                                    :set set)))))
+
+
+;;;; Inserting and getting icons.
+
+(defun icons--get-sorted-icons (name &optional _size)
+  "Return icons for NAME sorted by type and set.
+The order is given by `icons-type-priority', `icons-set-priority'
+and SIZE in that order.
+
+Optional argument SIZE, if non-nil."
+  (let ((icons (copy-sequence (cdr (assoc name icons-alist)))))
+    (sort icons
+          (lambda (A B)
+            (let ((Af (icons-icon-type A))
+                  (Bf (icons-icon-type B))
+                  (As (icons-icon-set A))
+                  (Bs (icons-icon-set B)))
+              (or (< (or (cl-position Af icons-type-priority) 
most-positive-fixnum)
+                     (or (cl-position Bf icons-type-priority) 
most-positive-fixnum))
+                  (< (or (cl-position As icons-set-priority) 
most-positive-fixnum)
+                     (or (cl-position Bs icons-set-priority) 
most-positive-fixnum))))))))
+
+(defun icons--image-spec-from-icon (icon)
+  "Return a specification for `find-image' based on `icons-icon' ICON."
+  (cl-assert (icons-icon-p icon))
+  (list :file (icons-icon-filename icon)
+        :type (icons-icon-type icon)
+        :ascent 'center
+        :height '(1 . em)))
+
+(defun icons--get-icon (name &optional _size)
+  "Return the best icon to use for NAME.
+The icon is found by `icons--get-sorted-icons' (which see)."
+  (or (when-let ((icons (icons--get-sorted-icons name)))
+        (find-image (mapcar #'icons--image-spec-from-icon icons)))
+      (error "Unable to find icon: `%s'" name)))
+
+;;;###autoload
+(defun icons-get (name &optional _size)
+  "Return icon NAME for inserting into a buffer.
+NAME is a string."
+  ;; FIXME: Size, based on default face.
+  ;; You should also be able to pass in a different face.
+  (if icons-enabled
+      (propertize " " 'display (icons--get-icon name))
+    ""))
+
+;;;###autoload
+(defun icons-get-filename (name &optional _size)
+  "Return filename of icon NAME.
+NAME is a string."
+  (plist-get (cdr (icons--get-icon name)) :file))
+
+;;;###autoload
+(defun icons-get-for-modeline (name)
+  "Return icon NAME for use in `mode-line-format'.
+NAME is as in `icons-get'."
+  (if icons-enabled
+      `(:propertize (" ") display ,(icons--get-icon name))
+    ""))
+
+;;;###autoload
+(defun icons-insert (name &optional _size)   ; FIXME: Is this very useful?
+  "Insert icon NAME at point.
+NAME is as in `icons-get'."
+  (when icons-enabled
+    (insert (icons-get name))))
+
+;; (defun icons--filename-for-size (font-size filename-alist)
+;;   "Return filename from FILENAME-ALIST closest to FONT-SIZE."
+;;   (if (listp filename-alist)
+;;       (let* ((sizes (map-keys filename-alist))
+;;              (size (icons--closest-to font-size sizes)))
+;;         (cdr (assq size filename-alist)))
+;;     filename-alist))
+
+
+;;;; Describing icons.
+
+(defface icons-description-title '((t :inherit bold)) "")
+(defface icons-icon-075 '((t :height 0.75)) "")
+(defface icons-icon-100 '((t :height 1.0)) "")
+(defface icons-icon-150 '((t :height 1.5)) "")
+(defface icons-icon-200 '((t :height 2.0)) "")
+(defface icons-icon-300 '((t :height 3.0)) "")
+(defface icons-icon-400 '((t :height 4.0)) "")
+
+(defun describe-icon (name)
+  "Describe icon NAME."
+  (interactive (list (completing-read (format-prompt "Describe icon" nil)
+                                      (sort (mapcar #'car icons-alist) 
#'string<))))
+  (let ((icon (cadr (assoc name icons-alist))))
+    (help-setup-xref (list #'describe-icon name)
+                     (called-interactively-p 'interactive))
+    (with-help-window (help-buffer)
+      (with-current-buffer standard-output
+        ;; TODO: Link the set name to corresponding `describe-icon-set'.
+        (insert (format-message "%S belongs to the icon set `%s'.\n\n"
+                                name (icons-icon-set icon)))
+
+        (insert (propertize "Filename:" 'face 'icons-description-title)
+                " "
+                (icons-icon-filename icon)
+                "\n")
+        (insert (propertize "Size:" 'face 'icons-description-title)
+                " "
+                (format "%s" (icons-icon-size icon))
+                "\n")
+        (insert (propertize "Type:" 'face 'icons-description-title)
+                " "
+                (format "%s" (icons-icon-type icon))
+                "\n")
+
+        (insert "\n")
+        (dolist (face '( icons-icon-075 icons-icon-100 icons-icon-150
+                         icons-icon-200 icons-icon-300 icons-icon-400))
+          (insert (propertize " " 'display '(space :align-to 2)))
+          (insert (propertize (icons-get name) 'face face))
+          (insert "\n\n"))))))
+
+;; (defun describe-icon-set (name)
+;;   "Describe icon set NAME."
+;;   (interactive
+;;    (list (completing-read (format-prompt "Describe icon set" nil)
+;;                           (sort icons-defined-sets
+;;                                 (lambda (a b)
+;;                                   (string< (symbol-name a) (symbol-name 
b)))))))
+;;   (help-setup-xref (list #'describe-icon-set name)
+;;                    (called-interactively-p 'interactive))
+;;   (with-help-window (help-buffer)
+;;     (with-current-buffer standard-output
+;;       ;; TODO: Link the set name to corresponding `describe-icon-set'.
+;;       (princ (format-message "Icon set `%s'.\n\n"
+;;                              (icons-icon-set icon)))
+;;       ;; TODO: Show all alternative icons in different sizes.
+;;       (icons-insert name))))
+
+
+;;;; Listing icons.
+
+(defconst icons-list-buffer-name "*Icons*")
+
+(defun icons-list-make-entries ()
+  "Make list of all icons for `tabulated-list-entries'."
+  (let (entries)
+    (dolist (ic icons-alist)
+      (let ((icon-name (car ic))
+            (icons (cdr ic)))
+        (dolist (icon icons)
+          (push (list (cons icon-name icon)
+                      (vector (symbol-name (icons-icon-set icon))
+                              icon-name
+                              (format "%s" (or (icons-icon-size icon) ""))
+                              (format "%s" (icons-icon-type icon))
+                              (find-image (list (icons--image-spec-from-icon 
icon )))))
+                entries))))
+    entries))
+
+;; Ignore arguments to be usable for `revert-buffer-function'.
+(defun icons-list-display (&optional _ _ _)
+  "Prepare buffer for `tabulated-list-mode' based on `icons-alist'."
+  (setq tabulated-list-entries (icons-list-make-entries))
+  (tabulated-list-init-header)
+  (tabulated-list-print t))
+
+(defvar-keymap icons-list-mode-map
+  :doc "Keymap for `icons-list-mode'."
+  "w" #'icons-list-copy-name)
+
+(define-derived-mode icons-list-mode tabulated-list-mode "Icons List Mode"
+  "Major mode for listing icons."
+  :interactive nil
+  (setq tabulated-list-format [("Icon set" 13 icons-list--icon-set-predicate)
+                               ("Name" 30 icons-list--name-predicate)
+                               ("Size" 6 icons-list--size-predicate)
+                               ("Type" 5)
+                               ("Icon" -1)])
+  (setq revert-buffer-function #'icons-list-display)
+  (setq tabulated-list-sort-key (cons "Size" nil)))
+
+;;;###autoload
+(defun list-icons ()
+  "Display all defined icons."
+  (interactive)
+  (pop-to-buffer (get-buffer-create icons-list-buffer-name))
+  (icons-list-mode)
+  (icons-list-display))
+
+(defun icons-list--name-predicate (A B)
+  "Predicate to sort `list-icons' by \"Name\"."
+  (string< (caar A) (caar B)))
+
+(defun icons-list--size-predicate (A B)
+  "Predicate to sort `list-icons' by \"Size\"."
+  (< (string-to-number (aref (cadr A) 2))
+     (string-to-number (aref (cadr B) 2))))
+
+(defun icons-list--icon-set-predicate (A B)
+  "Predicate to sort `list-icons' by Icon Set."
+  (let ((Aset (aref (cadr A) 0))
+        (Bset (aref (cadr B) 0)))
+    (if (string= Aset Bset)
+        ;; Secondary sort keys.
+        (or (icons-list--size-predicate A B)
+            (icons-list--name-predicate A B))
+      (string< Aset Bset))))
+
+(defun icons-list-copy-name ()
+  "In `icons-list-mode', copy name of icon at point."
+  (interactive nil icons-list-mode)
+  (let ((icon-name (aref (get-text-property (point) 'tabulated-list-entry) 1)))
+    (when icon-name
+      (kill-new icon-name)
+      (message "%s" icon-name))))
+
+;; (get-char-property (point) 'read-face-name)
+;; (get-char-property (point) 'font-lock-face)
+;; (get-char-property (point) 'face)
+
+
+;;;; Util.
+
+(defun icons--face-height-at-point ()
+  "Return font height at point."
+  (let* ((scale (cadr (assoc :height (assoc 'default face-remapping-alist))))
+         (face (face-font (or (face-at-point t) 'default)))
+         (height (* (aref (font-info face) 2) (if scale scale 1))))
+    height))
+
+(defun icons--closest-to (num candidates)
+  "Return the closest number to NUM among CANDIDATES."
+  (car (sort candidates (lambda (a b) (<= (abs (- num a))
+                                     (abs (- num b)))))))
+
+(icons-define-set 'emacs
+  '(
+    ("attach" "attach.pbm")
+    ("attach" "attach.xpm")
+    ("back-arrow" "back-arrow.pbm")
+    ("back-arrow" "back-arrow.xpm")
+    ("bookmark_add" "bookmark_add.pbm")
+    ("bookmark_add" "bookmark_add.xpm")
+    ("cancel" "cancel.pbm")
+    ("cancel" "cancel.xpm")
+    ("checkbox-mixed" "checkbox-mixed.svg")
+    ("checked" "checked.svg")
+    ("checked" "checked.xpm")
+    ("close" "close.pbm")
+    ("close" "close.xpm")
+    ("connect" "connect.pbm")
+    ("connect" "connect.xpm")
+    ("contact" "contact.pbm")
+    ("contact" "contact.xpm")
+    ("copy" "copy.pbm")
+    ("copy" "copy.xpm")
+    ("custom/down" "custom/down.pbm")
+    ("custom/down" "custom/down.xpm")
+    ("custom/down-pushed" "custom/down-pushed.pbm")
+    ("custom/down-pushed" "custom/down-pushed.xpm")
+    ("custom/right" "custom/right.pbm")
+    ("custom/right" "custom/right.xpm")
+    ("custom/right-pushed" "custom/right-pushed.pbm")
+    ("custom/right-pushed" "custom/right-pushed.xpm")
+    ("cut" "cut.pbm")
+    ("cut" "cut.xpm")
+    ("data-save" "data-save.pbm")
+    ("data-save" "data-save.xpm")
+    ("delete" "delete.pbm")
+    ("delete" "delete.xpm")
+    ("describe" "describe.pbm")
+    ("describe" "describe.xpm")
+    ("diropen" "diropen.pbm")
+    ("diropen" "diropen.xpm")
+    ("disconnect" "disconnect.pbm")
+    ("disconnect" "disconnect.xpm")
+    ("down" "down.svg")
+    ("exit" "exit.pbm")
+    ("exit" "exit.xpm")
+    ("ezimage/bits" "ezimage/bits.pbm")
+    ("ezimage/bits" "ezimage/bits.xpm")
+    ("ezimage/bitsbang" "ezimage/bitsbang.pbm")
+    ("ezimage/bitsbang" "ezimage/bitsbang.xpm")
+    ("ezimage/box" "ezimage/box.pbm")
+    ("ezimage/box" "ezimage/box.xpm")
+    ("ezimage/box-minus" "ezimage/box-minus.pbm")
+    ("ezimage/box-minus" "ezimage/box-minus.xpm")
+    ("ezimage/box-plus" "ezimage/box-plus.pbm")
+    ("ezimage/box-plus" "ezimage/box-plus.xpm")
+    ("ezimage/checkmark" "ezimage/checkmark.pbm")
+    ("ezimage/checkmark" "ezimage/checkmark.xpm")
+    ("ezimage/dir" "ezimage/dir.pbm")
+    ("ezimage/dir" "ezimage/dir.xpm")
+    ("ezimage/dir-minus" "ezimage/dir-minus.pbm")
+    ("ezimage/dir-minus" "ezimage/dir-minus.xpm")
+    ("ezimage/dir-plus" "ezimage/dir-plus.pbm")
+    ("ezimage/dir-plus" "ezimage/dir-plus.xpm")
+    ("ezimage/doc" "ezimage/doc.pbm")
+    ("ezimage/doc" "ezimage/doc.xpm")
+    ("ezimage/doc-minus" "ezimage/doc-minus.pbm")
+    ("ezimage/doc-minus" "ezimage/doc-minus.xpm")
+    ("ezimage/doc-plus" "ezimage/doc-plus.pbm")
+    ("ezimage/doc-plus" "ezimage/doc-plus.xpm")
+    ("ezimage/info" "ezimage/info.pbm")
+    ("ezimage/info" "ezimage/info.xpm")
+    ("ezimage/key" "ezimage/key.pbm")
+    ("ezimage/key" "ezimage/key.xpm")
+    ("ezimage/label" "ezimage/label.pbm")
+    ("ezimage/label" "ezimage/label.xpm")
+    ("ezimage/lock" "ezimage/lock.pbm")
+    ("ezimage/lock" "ezimage/lock.xpm")
+    ("ezimage/mail" "ezimage/mail.pbm")
+    ("ezimage/mail" "ezimage/mail.xpm")
+    ("ezimage/page" "ezimage/page.pbm")
+    ("ezimage/page" "ezimage/page.xpm")
+    ("ezimage/page-minus" "ezimage/page-minus.pbm")
+    ("ezimage/page-minus" "ezimage/page-minus.xpm")
+    ("ezimage/page-plus" "ezimage/page-plus.pbm")
+    ("ezimage/page-plus" "ezimage/page-plus.xpm")
+    ("ezimage/tag" "ezimage/tag.pbm")
+    ("ezimage/tag" "ezimage/tag.xpm")
+    ("ezimage/tag-gt" "ezimage/tag-gt.pbm")
+    ("ezimage/tag-gt" "ezimage/tag-gt.xpm")
+    ("ezimage/tag-minus" "ezimage/tag-minus.pbm")
+    ("ezimage/tag-minus" "ezimage/tag-minus.xpm")
+    ("ezimage/tag-plus" "ezimage/tag-plus.pbm")
+    ("ezimage/tag-plus" "ezimage/tag-plus.xpm")
+    ("ezimage/tag-type" "ezimage/tag-type.pbm")
+    ("ezimage/tag-type" "ezimage/tag-type.xpm")
+    ("ezimage/tag-v" "ezimage/tag-v.pbm")
+    ("ezimage/tag-v" "ezimage/tag-v.xpm")
+    ("ezimage/unlock" "ezimage/unlock.pbm")
+    ("ezimage/unlock" "ezimage/unlock.xpm")
+    ("fwd-arrow" "fwd-arrow.pbm")
+    ("fwd-arrow" "fwd-arrow.xpm")
+    ("gnus" "gnus.pbm")
+    ("gnus/followup" "gnus/followup.pbm")
+    ("gnus/followup" "gnus/followup.xpm")
+    ("gnus/fuwo" "gnus/fuwo.pbm")
+    ("gnus/fuwo" "gnus/fuwo.xpm")
+    ("gnus/gnus" "gnus/gnus.png")
+    ("gnus/gnus" "gnus/gnus.svg")
+    ("gnus/gnus" "gnus/gnus.xbm")
+    ("gnus/gnus" "gnus/gnus.xpm")
+    ("gnus/gnus-pointer" "gnus/gnus-pointer.xbm")
+    ("gnus/gnus-pointer" "gnus/gnus-pointer.xpm")
+    ("gnus/kill-group" "gnus/kill-group.pbm")
+    ("gnus/kill-group" "gnus/kill-group.xpm")
+    ("gnus/mail-reply" "gnus/mail-reply.pbm")
+    ("gnus/mail-reply" "gnus/mail-reply.xpm")
+    ("gnus/mail-send" "gnus/mail-send.pbm")
+    ("gnus/mail-send" "gnus/mail-send.xpm")
+    ("gnus/preview" "gnus/preview.xbm")
+    ("gnus/preview" "gnus/preview.xpm")
+    ("gnus/toggle-subscription" "gnus/toggle-subscription.pbm")
+    ("gnus/toggle-subscription" "gnus/toggle-subscription.xpm")
+    ("gud/all" "gud/all.pbm")
+    ("gud/all" "gud/all.xpm")
+    ("gud/break" "gud/break.pbm")
+    ("gud/break" "gud/break.xpm")
+    ("gud/cont" "gud/cont.pbm")
+    ("gud/cont" "gud/cont.xpm")
+    ("gud/down" "gud/down.pbm")
+    ("gud/down" "gud/down.xpm")
+    ("gud/finish" "gud/finish.pbm")
+    ("gud/finish" "gud/finish.xpm")
+    ("gud/go" "gud/go.pbm")
+    ("gud/go" "gud/go.xpm")
+    ("gud/next" "gud/next.pbm")
+    ("gud/next" "gud/next.xpm")
+    ("gud/nexti" "gud/nexti.pbm")
+    ("gud/nexti" "gud/nexti.xpm")
+    ("gud/pp" "gud/pp.pbm")
+    ("gud/pp" "gud/pp.xpm")
+    ("gud/print" "gud/print.pbm")
+    ("gud/print" "gud/print.xpm")
+    ("gud/pstar" "gud/pstar.pbm")
+    ("gud/pstar" "gud/pstar.xpm")
+    ("gud/rcont" "gud/rcont.pbm")
+    ("gud/rcont" "gud/rcont.xpm")
+    ("gud/recstart" "gud/recstart.pbm")
+    ("gud/recstart" "gud/recstart.xpm")
+    ("gud/recstop" "gud/recstop.pbm")
+    ("gud/recstop" "gud/recstop.xpm")
+    ("gud/remove" "gud/remove.pbm")
+    ("gud/remove" "gud/remove.xpm")
+    ("gud/rfinish" "gud/rfinish.pbm")
+    ("gud/rfinish" "gud/rfinish.xpm")
+    ("gud/rnext" "gud/rnext.pbm")
+    ("gud/rnext" "gud/rnext.xpm")
+    ("gud/rnexti" "gud/rnexti.pbm")
+    ("gud/rnexti" "gud/rnexti.xpm")
+    ("gud/rstep" "gud/rstep.pbm")
+    ("gud/rstep" "gud/rstep.xpm")
+    ("gud/rstepi" "gud/rstepi.pbm")
+    ("gud/rstepi" "gud/rstepi.xpm")
+    ("gud/run" "gud/run.pbm")
+    ("gud/run" "gud/run.xpm")
+    ("gud/step" "gud/step.pbm")
+    ("gud/step" "gud/step.xpm")
+    ("gud/stepi" "gud/stepi.pbm")
+    ("gud/stepi" "gud/stepi.xpm")
+    ("gud/stop" "gud/stop.pbm")
+    ("gud/stop" "gud/stop.xpm")
+    ("gud/thread" "gud/thread.pbm")
+    ("gud/thread" "gud/thread.xpm")
+    ("gud/until" "gud/until.pbm")
+    ("gud/until" "gud/until.xpm")
+    ("gud/up" "gud/up.pbm")
+    ("gud/up" "gud/up.xpm")
+    ("gud/watch" "gud/watch.pbm")
+    ("gud/watch" "gud/watch.xpm")
+    ("help" "help.pbm")
+    ("help" "help.xpm")
+    ("home" "home.pbm")
+    ("home" "home.xpm")
+    ("index" "index.pbm")
+    ("index" "index.xpm")
+    ("info" "info.pbm")
+    ("info" "info.xpm")
+    ("jump-to" "jump-to.pbm")
+    ("jump-to" "jump-to.xpm")
+    ("left" "left.svg")
+    ("left-arrow" "left-arrow.pbm")
+    ("left-arrow" "left-arrow.xpm")
+    ("letter" "letter.pbm")
+    ("letter" "letter.xpm")
+    ("lock" "lock.pbm")
+    ("lock" "lock.xpm")
+    ("lock-broken" "lock-broken.pbm")
+    ("lock-broken" "lock-broken.xpm")
+    ("lock-ok" "lock-ok.pbm")
+    ("lock-ok" "lock-ok.xpm")
+    ("low-color/back-arrow" "low-color/back-arrow.xpm")
+    ("low-color/copy" "low-color/copy.xpm")
+    ("low-color/cut" "low-color/cut.xpm")
+    ("low-color/fwd-arrow" "low-color/fwd-arrow.xpm")
+    ("low-color/help" "low-color/help.xpm")
+    ("low-color/home" "low-color/home.xpm")
+    ("low-color/index" "low-color/index.xpm")
+    ("low-color/jump-to" "low-color/jump-to.xpm")
+    ("low-color/left-arrow" "low-color/left-arrow.xpm")
+    ("low-color/new" "low-color/new.xpm")
+    ("low-color/next-node" "low-color/next-node.xpm")
+    ("low-color/open" "low-color/open.xpm")
+    ("low-color/paste" "low-color/paste.xpm")
+    ("low-color/preferences" "low-color/preferences.xpm")
+    ("low-color/prev-node" "low-color/prev-node.xpm")
+    ("low-color/print" "low-color/print.xpm")
+    ("low-color/right-arrow" "low-color/right-arrow.xpm")
+    ("low-color/save" "low-color/save.xpm")
+    ("low-color/saveas" "low-color/saveas.xpm")
+    ("low-color/search" "low-color/search.xpm")
+    ("low-color/spell" "low-color/spell.xpm")
+    ("low-color/undo" "low-color/undo.xpm")
+    ("low-color/up-arrow" "low-color/up-arrow.xpm")
+    ("low-color/up-node" "low-color/up-node.xpm")
+    ("mail/compose" "mail/compose.pbm")
+    ("mail/compose" "mail/compose.xpm")
+    ("mail/copy" "mail/copy.pbm")
+    ("mail/copy" "mail/copy.xpm")
+    ("mail/flag-for-followup" "mail/flag-for-followup.pbm")
+    ("mail/flag-for-followup" "mail/flag-for-followup.xpm")
+    ("mail/forward" "mail/forward.pbm")
+    ("mail/forward" "mail/forward.xpm")
+    ("mail/inbox" "mail/inbox.pbm")
+    ("mail/inbox" "mail/inbox.xpm")
+    ("mail/move" "mail/move.pbm")
+    ("mail/move" "mail/move.xpm")
+    ("mail/not-spam" "mail/not-spam.pbm")
+    ("mail/not-spam" "mail/not-spam.xpm")
+    ("mail/outbox" "mail/outbox.pbm")
+    ("mail/outbox" "mail/outbox.xpm")
+    ("mail/preview" "mail/preview.pbm")
+    ("mail/preview" "mail/preview.xpm")
+    ("mail/repack" "mail/repack.pbm")
+    ("mail/repack" "mail/repack.xpm")
+    ("mail/reply" "mail/reply.pbm")
+    ("mail/reply" "mail/reply.xpm")
+    ("mail/reply-all" "mail/reply-all.pbm")
+    ("mail/reply-all" "mail/reply-all.xpm")
+    ("mail/reply-from" "mail/reply-from.pbm")
+    ("mail/reply-from" "mail/reply-from.xpm")
+    ("mail/reply-to" "mail/reply-to.pbm")
+    ("mail/reply-to" "mail/reply-to.xpm")
+    ("mail/save" "mail/save.xpm")
+    ("mail/save-draft" "mail/save-draft.pbm")
+    ("mail/save-draft" "mail/save-draft.xpm")
+    ("mail/send" "mail/send.pbm")
+    ("mail/send" "mail/send.xpm")
+    ("mail/spam" "mail/spam.xpm")
+    ("mh-logo" "mh-logo.pbm")
+    ("mh-logo" "mh-logo.xpm")
+    ("mpc/add" "mpc/add.pbm")
+    ("mpc/add" "mpc/add.xpm")
+    ("mpc/ffwd" "mpc/ffwd.pbm")
+    ("mpc/ffwd" "mpc/ffwd.xpm")
+    ("mpc/next" "mpc/next.pbm")
+    ("mpc/next" "mpc/next.xpm")
+    ("mpc/pause" "mpc/pause.pbm")
+    ("mpc/pause" "mpc/pause.xpm")
+    ("mpc/play" "mpc/play.pbm")
+    ("mpc/play" "mpc/play.xpm")
+    ("mpc/prev" "mpc/prev.pbm")
+    ("mpc/prev" "mpc/prev.xpm")
+    ("mpc/rewind" "mpc/rewind.pbm")
+    ("mpc/rewind" "mpc/rewind.xpm")
+    ("mpc/stop" "mpc/stop.pbm")
+    ("mpc/stop" "mpc/stop.xpm")
+    ("new" "new.pbm")
+    ("new" "new.xpm")
+    ("newsticker/browse-url" "newsticker/browse-url.xpm")
+    ("newsticker/get-all" "newsticker/get-all.xpm")
+    ("newsticker/mark-immortal" "newsticker/mark-immortal.xpm")
+    ("newsticker/mark-read" "newsticker/mark-read.xpm")
+    ("newsticker/narrow" "newsticker/narrow.xpm")
+    ("newsticker/next-feed" "newsticker/next-feed.xpm")
+    ("newsticker/next-item" "newsticker/next-item.xpm")
+    ("newsticker/prev-feed" "newsticker/prev-feed.xpm")
+    ("newsticker/prev-item" "newsticker/prev-item.xpm")
+    ("newsticker/rss-feed" "newsticker/rss-feed.png")
+    ("newsticker/rss-feed" "newsticker/rss-feed.svg")
+    ("newsticker/update" "newsticker/update.xpm")
+    ("next-node" "next-node.pbm")
+    ("next-node" "next-node.xpm")
+    ("next-page" "next-page.pbm")
+    ("next-page" "next-page.xpm")
+    ("open" "open.pbm")
+    ("open" "open.xpm")
+    ("paste" "paste.pbm")
+    ("paste" "paste.xpm")
+    ("preferences" "preferences.pbm")
+    ("preferences" "preferences.xpm")
+    ("prev-node" "prev-node.pbm")
+    ("prev-node" "prev-node.xpm")
+    ("print" "print.pbm")
+    ("print" "print.xpm")
+    ("radio" "radio.svg")
+    ("radio-checked" "radio-checked.svg")
+    ("radio-mixed" "radio-mixed.svg")
+    ("redo" "redo.pbm")
+    ("redo" "redo.xpm")
+    ("refresh" "refresh.pbm")
+    ("refresh" "refresh.xpm")
+    ("right" "right.svg")
+    ("right-arrow" "right-arrow.pbm")
+    ("right-arrow" "right-arrow.xpm")
+    ("save" "save.pbm")
+    ("save" "save.xpm")
+    ("saveas" "saveas.pbm")
+    ("saveas" "saveas.xpm")
+    ("search" "search.pbm")
+    ("search" "search.xpm")
+    ("search-replace" "search-replace.pbm")
+    ("search-replace" "search-replace.xpm")
+    ("separator" "separator.pbm")
+    ("separator" "separator.xpm")
+    ("show" "show.pbm")
+    ("show" "show.xpm")
+    ("smilies/blink" "smilies/blink.pbm")
+    ("smilies/blink" "smilies/blink.xpm")
+    ("smilies/braindamaged" "smilies/braindamaged.pbm")
+    ("smilies/braindamaged" "smilies/braindamaged.xpm")
+    ("smilies/cry" "smilies/cry.pbm")
+    ("smilies/cry" "smilies/cry.xpm")
+    ("smilies/dead" "smilies/dead.pbm")
+    ("smilies/dead" "smilies/dead.xpm")
+    ("smilies/evil" "smilies/evil.pbm")
+    ("smilies/evil" "smilies/evil.xpm")
+    ("smilies/forced" "smilies/forced.pbm")
+    ("smilies/forced" "smilies/forced.xpm")
+    ("smilies/frown" "smilies/frown.pbm")
+    ("smilies/frown" "smilies/frown.xpm")
+    ("smilies/grin" "smilies/grin.pbm")
+    ("smilies/grin" "smilies/grin.xpm")
+    ("smilies/indifferent" "smilies/indifferent.pbm")
+    ("smilies/indifferent" "smilies/indifferent.xpm")
+    ("smilies/sad" "smilies/sad.pbm")
+    ("smilies/sad" "smilies/sad.xpm")
+    ("smilies/smile" "smilies/smile.pbm")
+    ("smilies/smile" "smilies/smile.xpm")
+    ("smilies/wry" "smilies/wry.pbm")
+    ("smilies/wry" "smilies/wry.xpm")
+    ("sort-ascending" "sort-ascending.pbm")
+    ("sort-ascending" "sort-ascending.xpm")
+    ("sort-column-ascending" "sort-column-ascending.pbm")
+    ("sort-column-ascending" "sort-column-ascending.xpm")
+    ("sort-criteria" "sort-criteria.pbm")
+    ("sort-criteria" "sort-criteria.xpm")
+    ("sort-descending" "sort-descending.pbm")
+    ("sort-descending" "sort-descending.xpm")
+    ("sort-row-ascending" "sort-row-ascending.pbm")
+    ("sort-row-ascending" "sort-row-ascending.xpm")
+    ("spell" "spell.pbm")
+    ("spell" "spell.xpm")
+    ("tabs/close" "tabs/close.xpm")
+    ("tabs/left-arrow" "tabs/left-arrow.xpm")
+    ("tabs/new" "tabs/new.xpm")
+    ("tabs/right-arrow" "tabs/right-arrow.xpm")
+    ("tree-widget/default/close" "tree-widget/default/close.png")
+    ("tree-widget/default/close" "tree-widget/default/close.xpm")
+    ("tree-widget/default/empty" "tree-widget/default/empty.png")
+    ("tree-widget/default/empty" "tree-widget/default/empty.xpm")
+    ("tree-widget/default/end-guide" "tree-widget/default/end-guide.png")
+    ("tree-widget/default/end-guide" "tree-widget/default/end-guide.xpm")
+    ("tree-widget/default/guide" "tree-widget/default/guide.png")
+    ("tree-widget/default/guide" "tree-widget/default/guide.xpm")
+    ("tree-widget/default/handle" "tree-widget/default/handle.png")
+    ("tree-widget/default/handle" "tree-widget/default/handle.xpm")
+    ("tree-widget/default/leaf" "tree-widget/default/leaf.png")
+    ("tree-widget/default/leaf" "tree-widget/default/leaf.xpm")
+    ("tree-widget/default/no-guide" "tree-widget/default/no-guide.png")
+    ("tree-widget/default/no-guide" "tree-widget/default/no-guide.xpm")
+    ("tree-widget/default/no-handle" "tree-widget/default/no-handle.png")
+    ("tree-widget/default/no-handle" "tree-widget/default/no-handle.xpm")
+    ("tree-widget/default/open" "tree-widget/default/open.png")
+    ("tree-widget/default/open" "tree-widget/default/open.xpm")
+    ("tree-widget/folder/close" "tree-widget/folder/close.png")
+    ("tree-widget/folder/close" "tree-widget/folder/close.xpm")
+    ("tree-widget/folder/empty" "tree-widget/folder/empty.png")
+    ("tree-widget/folder/empty" "tree-widget/folder/empty.xpm")
+    ("tree-widget/folder/end-guide" "tree-widget/folder/end-guide.png")
+    ("tree-widget/folder/end-guide" "tree-widget/folder/end-guide.xpm")
+    ("tree-widget/folder/guide" "tree-widget/folder/guide.png")
+    ("tree-widget/folder/guide" "tree-widget/folder/guide.xpm")
+    ("tree-widget/folder/handle" "tree-widget/folder/handle.png")
+    ("tree-widget/folder/handle" "tree-widget/folder/handle.xpm")
+    ("tree-widget/folder/leaf" "tree-widget/folder/leaf.png")
+    ("tree-widget/folder/leaf" "tree-widget/folder/leaf.xpm")
+    ("tree-widget/folder/no-guide" "tree-widget/folder/no-guide.png")
+    ("tree-widget/folder/no-guide" "tree-widget/folder/no-guide.xpm")
+    ("tree-widget/folder/no-handle" "tree-widget/folder/no-handle.png")
+    ("tree-widget/folder/no-handle" "tree-widget/folder/no-handle.xpm")
+    ("tree-widget/folder/open" "tree-widget/folder/open.png")
+    ("tree-widget/folder/open" "tree-widget/folder/open.xpm")
+    ("unchecked" "unchecked.pbm")
+    ("unchecked" "unchecked.svg")
+    ("unchecked" "unchecked.xpm")
+    ("undo" "undo.pbm")
+    ("undo" "undo.xpm")
+    ("up" "up.svg")
+    ("up-arrow" "up-arrow.pbm")
+    ("up-arrow" "up-arrow.xpm")
+    ("up-node" "up-node.pbm")
+    ("up-node" "up-node.xpm")
+    ("zoom-in" "zoom-in.pbm")
+    ("zoom-in" "zoom-in.xpm")
+    ("zoom-out" "zoom-out.pbm")
+    ("zoom-out" "zoom-out.xpm")
+    ;; ("smilies/grayscale/blink" "smilies/grayscale/blink.xpm")
+    ;; ("smilies/grayscale/braindamaged" "smilies/grayscale/braindamaged.xpm")
+    ;; ("smilies/grayscale/cry" "smilies/grayscale/cry.xpm")
+    ;; ("smilies/grayscale/dead" "smilies/grayscale/dead.xpm")
+    ;; ("smilies/grayscale/evil" "smilies/grayscale/evil.xpm")
+    ;; ("smilies/grayscale/forced" "smilies/grayscale/forced.xpm")
+    ;; ("smilies/grayscale/frown" "smilies/grayscale/frown.xpm")
+    ;; ("smilies/grayscale/grin" "smilies/grayscale/grin.xpm")
+    ;; ("smilies/grayscale/indifferent" "smilies/grayscale/indifferent.xpm")
+    ;; ("smilies/grayscale/reverse-smile" 
"smilies/grayscale/reverse-smile.xpm")
+    ;; ("smilies/grayscale/sad" "smilies/grayscale/sad.xpm")
+    ;; ("smilies/grayscale/smile" "smilies/grayscale/smile.xpm")
+    ;; ("smilies/grayscale/wry" "smilies/grayscale/wry.xpm")
+    ;; ("smilies/medium/blink" "smilies/medium/blink.xpm")
+    ;; ("smilies/medium/braindamaged" "smilies/medium/braindamaged.xpm")
+    ;; ("smilies/medium/cry" "smilies/medium/cry.xpm")
+    ;; ("smilies/medium/dead" "smilies/medium/dead.xpm")
+    ;; ("smilies/medium/evil" "smilies/medium/evil.xpm")
+    ;; ("smilies/medium/forced" "smilies/medium/forced.xpm")
+    ;; ("smilies/medium/frown" "smilies/medium/frown.xpm")
+    ;; ("smilies/medium/grin" "smilies/medium/grin.xpm")
+    ;; ("smilies/medium/indifferent" "smilies/medium/indifferent.xpm")
+    ;; ("smilies/medium/reverse-smile" "smilies/medium/reverse-smile.xpm")
+    ;; ("smilies/medium/sad" "smilies/medium/sad.xpm")
+    ;; ("smilies/medium/smile" "smilies/medium/smile.xpm")
+    ;; ("smilies/medium/wry" "smilies/medium/wry.xpm")
+    ;; ("splash" "splash.bmp")
+    ;; ("splash" "splash.pbm")
+    ;; ("splash" "splash.png")
+    ;; ("splash" "splash.svg")
+    ;; ("splash" "splash.xpm")
+    ))
+
+(provide 'icons)
+;;; icons.el ends here
diff --git a/test/lisp/icons-resources/apple.pbm 
b/test/lisp/icons-resources/apple.pbm
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/lisp/icons-resources/apple.svg 
b/test/lisp/icons-resources/apple.svg
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/lisp/icons-resources/apple.xpm 
b/test/lisp/icons-resources/apple.xpm
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/lisp/icons-resources/apple2.svg 
b/test/lisp/icons-resources/apple2.svg
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/lisp/icons-resources/lemon.svg 
b/test/lisp/icons-resources/lemon.svg
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/lisp/icons-resources/orange.svg 
b/test/lisp/icons-resources/orange.svg
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/test/lisp/icons-tests.el b/test/lisp/icons-tests.el
new file mode 100644
index 0000000000..39fc51635c
--- /dev/null
+++ b/test/lisp/icons-tests.el
@@ -0,0 +1,131 @@
+;;; icons-tests.el --- tests for icons.el -*- lexical-binding: t -*-
+
+;; Copyright (C) 2021 Free Software Foundation, Inc.
+
+;; Author: Stefan Kangas <stefankangas@gmail.com>
+
+;; This file is part of GNU Emacs.
+
+;; 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 GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.
+
+;;; Code:
+
+(require 'ert)
+(require 'ert-x)
+(require 'icons)
+
+(defmacro with-icons-test (&rest body)
+  (declare (indent defun))
+  `(let (icons-alist
+         (image-load-path (cons
+                           (ert-resource-directory)
+                           image-load-path))
+         (icons-format-priority '(svg xpm pbm)))
+     (icons-define-set 'set1 `(("apple" "apple2.svg" 24)
+                         ("orange" "orange.svg" 24)
+                         ("lemon" "lemon.svg")))
+     (icons-define-set 'set2 `(("apple" "apple.svg")))
+     (icons-define-set 'xpmset `(("apple" "apple.xpm")))
+     (icons-define-set 'pbmset `(("apple" "apple.pbm")))
+     ,@body))
+
+;;;; Data.
+
+(ert-deftest icons-define-set ()
+  (with-icons-test
+    (should (= (length (cdr (assoc "apple" icons-alist))) 4))))
+
+;;;; Inserting and getting icons.
+
+(ert-deftest icons--get-icon ()
+  (with-icons-test
+    (let ((icon (cdr (icons--get-icon "apple"))))
+      (plist-get icon :file)
+      (should (string-match "apple\.svg\\'"
+                            (plist-get icon :file))))))
+
+(ert-deftest icons--get-icon/missing ()
+  (with-icons-test
+    (should-error (icons--get-icon "foo-missing-icon"))))
+
+(ert-deftest icons--get-sorted-icons/format-priority ()
+  (with-icons-test
+    (should (eq (icons-icon-type (car (last (icons--get-sorted-icons 
"apple"))))
+                (car (last icons-format-priority))))))
+
+(ert-deftest icons--get-sorted-icons/set-priority ()
+  (let ((icons-set-priority '(set1 set2)))
+    (with-icons-test
+      (should (equal (icons-icon-filename (car (icons--get-sorted-icons 
"apple")))
+                     "apple2.svg"))))
+  (let ((icons-set-priority '(set2 set1)))
+    (with-icons-test
+      (should (equal (icons-icon-filename (car (icons--get-sorted-icons 
"apple")))
+                     "apple.svg")))))
+
+(ert-deftest icons-get/returns-space ()
+  (with-icons-test
+    (should (equal (with-icons-test (icons-get "apple")) " "))))
+
+(ert-deftest icons-get/has-display-property ()
+  (should (get-text-property 0 'display (with-icons-test (icons-get 
"apple")))))
+
+(ert-deftest icons-get-icon ()
+  (should (eq (car (with-icons-test (icons-get-for-modeline "apple")))
+              :propertize)))
+
+(ert-deftest icons-tests--remove-set ()
+  (with-icons-test
+   (icons--remove-set 'set1)
+   (icons--remove-set 'set2)
+   (icons--remove-set 'xpmset)
+   (icons--remove-set 'pbmset)
+   (should (not icons-alist))))
+
+;; (ert-deftest icons-add-icon ()
+;;   (let (icons-alist
+;;         (icon (icons-icon-create :filename "bar" :set 'set)))
+;;     (icons-add-icon "foo" icon)
+;;     (should (assoc "foo" icons-alist))
+;;     ;; Invalid names.
+;;     (should-error (icons-add-icon nil icon))
+;;     (should-error (icons-add-icon 'foo icon))
+;;     ;; Invalid icons.
+;;     (should-error (icons-add-icon "foo" "not an icon"))))
+
+;; (ert-deftest test-list-make-entries ()
+;;   (with-icons-test
+;;    (let ((entries (icons-list-make-entries)))
+;;      (should (listp entries))
+;;      (should (= (length entries) 2)))))
+
+;; (ert-deftest test-icons--filename-for-size/string ()
+;;   (should (equal (icons--filename-for-size 20 "foobar")
+;;                  "foobar")))
+
+;; (ert-deftest test-icons--filename-for-size/alist ()
+;;   (should (equal (icons--filename-for-size 20 '((5 . "foo")
+;;                                            (10 . "bar")))
+;;                  "bar")))
+
+;;;; Util.
+
+(ert-deftest test-icons--find-closest ()
+  (should (= (icons--closest-to 14 '(10 20)) 10))
+  (should (= (icons--closest-to 15 '(10 20)) 20))
+  (should (= (icons--closest-to 8 '(6 12)) 6))
+  (should (= (icons--closest-to 9 '(6 12)) 12))
+  (should (= (icons--closest-to 14 '(10 18 20)) 18)))
+
+;;; icons-tests.el ends here