css-mode documentation lookup feature

* etc/NEWS: Mention new feature.
* lisp/textmodes/css-mode.el (css-mode-map): New defvar.
(css--mdn-lookup-history): New defvar.
(css-lookup-url-format): New defcustom.
(css--mdn-property-regexp, css--mdn-completion-list): New defconsts.
(css--mdn-after-render, css--mdn-find-symbol, css-lookup-symbol): New
defuns.
* test/lisp/textmodes/css-mode-tests.el (css-mdn-symbol-guessing): New
test.

1 files changed, 15 insertions, 0 deletions

diff --git a/test/lisp/textmodes/css-mode-tests.el b/test/lisp/textmodes/css-mode-tests.el
index 6eb32ea7fc4..5372c37a179 100644
--- a/test/lisp/textmodes/css-mode-tests.el
+++ b/test/lisp/textmodes/css-mode-tests.el
@@ -218,5 +218,20 @@
       (should (member "body" completions))
       (should-not (member "article" completions)))))
 
+(ert-deftest css-mdn-symbol-guessing ()
+  (dolist (item '(("@med" "ia" "@media")
+                  ("@keyframes " "{" "@keyframes")
+                  ("p::after" "" "::after")
+                  ("p:before" "" ":before")
+                  ("a:v" "isited" ":visited")
+                  ("border-" "color: red" "border-color")
+                  ("border-color: red" ";" "border-color")
+                  ("border-color: red; color: green" ";" "color")))
+    (with-temp-buffer
+      (css-mode)
+      (insert (nth 0 item))
+      (save-excursion (insert (nth 1 item)))
+      (should (equal (nth 2 item) (css--mdn-find-symbol))))))
+
 (provide 'css-mode-tests)
 ;;; css-mode-tests.el ends here