[PATCH 4/4 v3] emacs: Take more care when hiding regions with buttons.

[David Edmondson]

If the region to be hidden with a button by
`notmuch-wash-region-to-button' starts at the beginning of the buffer,
the invisible region will include the inserted button. This is
unfortunate, as it means that it is not possible to see the button to
be pressed.

Make a little space at the start of the buffer before inserting the
button to avoid this, not forgetting to remove the inserted space upon
completion.

Mark the relevant test as no longer broken.
---
 emacs/notmuch-wash.el        |   57 ++++++++++++++++++++++++++++--------------
 test/emacs-message-hiding.sh |    1 -
 2 files changed, 38 insertions(+), 20 deletions(-)

diff --git a/emacs/notmuch-wash.el b/emacs/notmuch-wash.el
index 5c1e830..4afd3b3 100644
--- a/emacs/notmuch-wash.el
+++ b/emacs/notmuch-wash.el
@@ -147,25 +147,44 @@ insert before the button, probably for indentation."
   ;; symbols because of the way the button code works. Note that
   ;; replacing intern-soft with make-symbol will cause this to fail,
   ;; since the newly created symbol has no plist.
-
-  (let ((overlay (make-overlay beg end))
-	(message-invis-spec (plist-get msg :message-invis-spec))
-	(invis-spec (make-symbol (concat "notmuch-" type "-region")))
-	(button-type (intern-soft (concat "notmuch-wash-button-"
-					  type "-toggle-type"))))
-    (add-to-invisibility-spec invis-spec)
-    (overlay-put overlay 'invisible (list invis-spec message-invis-spec))
-    (overlay-put overlay 'isearch-open-invisible #'notmuch-wash-region-isearch-show)
-    (overlay-put overlay 'priority 10)
-    (overlay-put overlay 'type type)
-    (goto-char (1+ end))
-    (save-excursion
-      (goto-char (1- beg))
-      (insert prefix)
-      (insert-button (notmuch-wash-button-label overlay)
-		     'invisibility-spec invis-spec
-		     'overlay overlay
-		     :type button-type))))
+  (save-excursion
+    ;; If the beginning of the region to be converted to a button is the
+    ;; beginning of the buffer we must move forward a little to avoid
+    ;; creating an overlay that will hide the button intended to be used
+    ;; to reveal the hidden region.
+    (let (scene-of-crime)
+      (when (eq beg (point-min))
+	(goto-char (point-min))
+	(insert "\n")
+	(setq scene-of-crime (point-min)
+	      beg (point)))
+
+      ;; This uses some slightly tricky conversions between strings and
+      ;; symbols because of the way the button code works. Note that
+      ;; replacing intern-soft with make-symbol will cause this to fail,
+      ;; since the newly created symbol has no plist.
+
+      (let ((overlay (make-overlay beg end))
+	    (message-invis-spec (plist-get msg :message-invis-spec))
+	    (invis-spec (make-symbol (concat "notmuch-" type "-region")))
+	    (button-type (intern-soft (concat "notmuch-wash-button-"
+					      type "-toggle-type"))))
+	(add-to-invisibility-spec invis-spec)
+	(overlay-put overlay 'invisible (list invis-spec message-invis-spec))
+	(overlay-put overlay 'isearch-open-invisible #'notmuch-wash-region-isearch-show)
+	(overlay-put overlay 'priority 10)
+	(overlay-put overlay 'type type)
+
+	(goto-char (1- beg))
+	(insert prefix)
+	(insert-button (notmuch-wash-button-label overlay)
+		       'invisibility-spec invis-spec
+		       'overlay overlay
+		       :type button-type))
+
+      (when scene-of-crime
+      	(goto-char scene-of-crime)
+      	(delete-char 1)))))
 
 (defun notmuch-wash-excerpt-citations (msg depth)
   "Excerpt citations and up to one signature."
diff --git a/test/emacs-message-hiding.sh b/test/emacs-message-hiding.sh
index 70bc66d..36708d7 100755
--- a/test/emacs-message-hiding.sh
+++ b/test/emacs-message-hiding.sh
@@ -31,7 +31,6 @@ test_emacs '
    (visible-buffer-string)))
 '
 
-test_subtest_known_broken
 test_expect_equal_file EXPECTED OUTPUT
 
 test_done
-- 
1.7.8.3