Improve rendering of documents with no pages.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/documents/tests/test_widgets.py

@@ -0,0 +1,14 @@
+from __future__ import unicode_literals
+
+from ..widgets import DocumentThumbnailWidget
+
+from .test_models import GenericDocumentTestCase
+
+
+class DocumentWidgetTestCase(GenericDocumentTestCase):
+    def test_document_list_view_document_with_no_pages(self):
+        document_thumbnail_widget = DocumentThumbnailWidget()
+        self.document.pages.all().delete()
+        result = document_thumbnail_widget.render(instance=self.document)
+
+        self.assertTrue(self.document.get_absolute_url() in result)