Fix nesting bug

* snippet-tests.el (nested-skip-fields, navigate-fields-and-exit):
Fix test.
(wrap-selected-region): Use eval trick temporarily.
(snippet--test-fixture): New helper.

* snippet.el (snippet--debug-snippet): More stable sort in
debugging helper.

* snippet.el (with-dynamic-snippet): Fix nesting.
(snippet--call-with-inserting-object): Fix setting the `prev'
slot.
(snippet--call-with-inserting-object): Fix nesting.

snippet-tests.el

@@ -197,7 +197,7 @@
   ;; this should exit the snippet now, since the two remaining
   ;; fields should be skipped
   (ert-simulate-command '(snippet-next-field))
-  (should (null (overlay-buffer snippet--field-overlay))))
+  (should (null snippet--field-overlay)))
 
 (snippet--define-expansion-test mirror-of-nested-field mirror-of-nested-field()
   (should (equal (buffer-string) "a nested field, nested mirroring: field"))
@@ -274,13 +274,11 @@
     (ert-simulate-command '((lambda () (interactive) (insert "bar"))))
     (set-mark (point))
     (goto-char (point-max))
-    (snippet--insert-test-snippet 'wrap-selected-region)
+    (eval `(with-static-snippet ,@(snippet--get-fixture 'wrap-selected-region)))
     (should (equal (buffer-string)
                    "foobarbazbar"))))
 
-(ert-deftest navigate-fields-and-exit ()
+(snippet--define-expansion-test navigate-fields-and-exit navigate-fields()
-  (with-temp-buffer
-    (snippet--insert-test-snippet 'navigate-fields)
   (should (equal (buffer-string) "foo"))
   (ert-simulate-command '((lambda () (interactive) (insert "quam"))))
   (ert-simulate-command '(snippet-next-field))
@@ -291,8 +289,8 @@
   (ert-simulate-command '((lambda () (interactive) (insert "quux"))))
   (ert-simulate-command '(snippet-next-field))
   (should (equal (buffer-string) "foobarbazquuxquam"))
-    (should (null (overlay-buffer snippet--field-overlay)))
+  (should (null snippet--field-overlay))
-    (should (looking-at "barbazquuxquam"))))
+  (should (looking-at "barbazquuxquam")))
 
 
 ;;; input validation
@@ -347,7 +345,8 @@
   (should-error (snippet--canonicalize-form '(&eval (foo) (bar)))))
 
 
-;; pretty forms
+;; misc
+;; 
 (cl-loop for sym in (list 'snippet--define-expansion-test)
          for regexp = (format "(\\(%S\\)\\s +\\(\\(\\w\\|\\s_\\)+\\)"
                               sym)
@@ -356,5 +355,13 @@
              `((,regexp (1 font-lock-keyword-face)
                         (2 font-lock-variable-name-face)))))
 
+(defun snippet--test-fixture (fixture &optional dynamic)
+  (with-current-buffer (get-buffer-create "*snippet-test*")
+    (erase-buffer)
+    (switch-to-buffer (current-buffer))
+    (if dynamic
+        (eval `(with-dynamic-snippet ,@(snippet--get-fixture fixture 'dynamic-p)))
+      (eval `(with-static-snippet ,@(snippet--get-fixture fixture nil))))))
+
 (provide 'snippet-tests)
 

snippet.el

@@ -315,18 +315,17 @@ pairs. Its meaning is not decided yet"
          (snippet--prev-object)
          (snippet--all-objects))
      (cl-macrolet ((&field (field-name &body field-forms)
-                     `(let* ((field
+                     `(let ((fn (lambda () ,@field-forms))
+                            (field
                              (setf (gethash ',field-name snippet--fields)
                                    (make-instance 'snippet--field
                                                   :name ',field-name
-                                                   :parent snippet--current-field)))
+                                                  :parent snippet--current-field))))
-                             (fn (lambda ()
-                                   (let ((snippet--current-field field))
-                                     ,@field-forms))))
                         (snippet--inserting-object
                           field snippet--prev-object
-                          (funcall fn))
                           (setf snippet--prev-object field)
+                          (let ((snippet--current-field field))
+                            (funcall fn)))
                         (push field snippet--all-objects)))
                    (&mirror (field-name mirror-args &body mirror-forms)
                      (cond ((> (length mirror-args) 2)
@@ -404,6 +403,7 @@ pairs. Its meaning is not decided yet"
 
 (defun snippet--call-with-inserting-object (object prev fn)
   (when prev
+    (setf (snippet--object-prev object) prev)
     (cl-assert (null (snippet--object-next prev)) nil
                "previous object already has another sucessor")
     (setf (snippet--object-next prev) object))
@@ -424,8 +424,11 @@ pairs. Its meaning is not decided yet"
                 (t
                  (point-marker)))))
   (funcall fn)
+  ;; Only set the object's end if not set yet, i.e. when running its function
+  ;; some nested field might have set it already.
+  (unless (snippet--object-end object)
     (setf (snippet--object-end object)
-        (point-marker))
+          (point-marker)))
   (when (snippet--object-parent object)
     (setf (snippet--object-end
            (snippet--object-parent object))