check for libxml when trying to use eww

Author: Danny McClanahan

markdown-mode.el

@@ -5327,9 +5327,13 @@ buffer. Inverse of `markdown-live-preview-view-buffer'.")
   "Status of sync or async live preview in current buffer.")
 (make-variable-buffer-local 'markdown-live-preview-current-buffer-sync-async)
 
+(defun markdown-live-preview-has-eww-p ()
+  (and (require 'eww nil t)
+       (fboundp 'libxml-parse-html-region)))
+
 (defun markdown-live-preview-window-eww (file)
   "A `markdown-live-preview-window-function' for previewing with `eww'."
-  (if (require 'eww nil t)
+  (if (markdown-live-preview-has-eww-p)
       (progn
         (eww-open-file file)
         (get-buffer "*eww*"))

tests/markdown-test.el

@@ -3290,7 +3290,7 @@ indented the same amount."
 
 (defmacro markdown-temp-eww (&rest body)
   `(progn
-     ,@(if (require 'eww nil t) body
+     ,@(if (markdown-live-preview-has-eww-p) body
          `((ad-enable-advice #'markdown-live-preview-window-eww
                              'around 'markdown-create-fake-eww)
            (ad-activate #'markdown-live-preview-window-eww)
@@ -3324,7 +3324,7 @@ indented the same amount."
 
 (ert-deftest test-markdown-ext/live-preview-exports-sync ()
   (let ((markdown-live-preview-do-sync t))
-    (unless (require 'eww nil t)
+    (unless (markdown-live-preview-has-eww-p)
       (should-error (markdown-live-preview-sync-export)))
     (markdown-test/live-preview-exports)))
 
@@ -3370,13 +3370,27 @@ indented the same amount."
   (setq markdown-test-hit-advice t)
   (should (eq (selected-window) markdown-test-eww-window)))
 
+(defadvice get-buffer-create (before markdown-set-window-width-mock disable)
+  (when (let ((buf (ad-get-arg 0))) (and (stringp buf) (string= buf "*eww*")))
+    (setq markdown-test-hit-advice t)
+    (should (eq (selected-window) markdown-test-eww-window))))
+
 (defmacro markdown-eww-open-file-advice (&rest body)
-  `(progn
-     (ad-enable-advice #'eww-open-file 'before 'markdown-set-window-width)
-     (ad-activate #'eww-open-file)
-     ,@body
-     (ad-disable-advice #'eww-open-file 'before 'markdown-set-window-width)
-     (ad-activate #'eww-open-file)))
+  (if (markdown-live-preview-has-eww-p)
+      `(progn
+         (ad-enable-advice #'eww-open-file 'before 'markdown-set-window-width)
+         (ad-activate #'eww-open-file)
+         ,@body
+         (ad-disable-advice #'eww-open-file 'before 'markdown-set-window-width)
+         (ad-activate #'eww-open-file))
+    `(progn
+       (ad-enable-advice #'get-buffer-create 'before 
+                         'markdown-set-window-width-mock)
+       (ad-activate #'get-buffer-create)
+       ,@body
+       (ad-disable-advice #'get-buffer-create 'before
+                          'markdown-set-window-width-mock)
+       (ad-activate #'get-buffer-create))))
 
 (defun markdown-test/test-window-size-eww ()
   (setq markdown-test-hit-advice nil)
@@ -3401,7 +3415,6 @@ indented the same amount."
                 (markdown-live-preview-sync-export)
               (markdown-live-preview-async-export))
             (markdown-test/live-preview-wait)
-            (sit-for .1)
             ;; at this point, `eww-render' should have finished, and eww should
             ;; have redisplayed. the advice checks that, since there was a
             ;; single window displaying the *eww* buffer, that window was used