diff -r 000000000000 -r 6474c204b198 browser/base/content/test/newtab/browser_newtab_block.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/browser/base/content/test/newtab/browser_newtab_block.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,61 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+/*
+ * These tests make sure that blocking/removing sites from the grid works
+ * as expected. Pinned tabs should not be moved. Gaps will be re-filled
+ * if more sites are available.
+ */
+function runTests() {
+  // we remove sites and expect the gaps to be filled as long as there still
+  // are some sites available
+  yield setLinks("0,1,2,3,4,5,6,7,8,9");
+  setPinnedLinks("");
+
+  yield addNewTabPageTab();
+  checkGrid("0,1,2,3,4,5,6,7,8");
+
+  yield blockCell(4);
+  checkGrid("0,1,2,3,5,6,7,8,9");
+
+  yield blockCell(4);
+  checkGrid("0,1,2,3,6,7,8,9,");
+
+  yield blockCell(4);
+  checkGrid("0,1,2,3,7,8,9,,");
+
+  // we removed a pinned site
+  yield restore();
+  yield setLinks("0,1,2,3,4,5,6,7,8");
+  setPinnedLinks(",1");
+
+  yield addNewTabPageTab();
+  checkGrid("0,1p,2,3,4,5,6,7,8");
+
+  yield blockCell(1);
+  checkGrid("0,2,3,4,5,6,7,8,");
+
+  // we remove the last site on the grid (which is pinned) and expect the gap
+  // to be re-filled and the new site to be unpinned
+  yield restore();
+  yield setLinks("0,1,2,3,4,5,6,7,8,9");
+  setPinnedLinks(",,,,,,,,8");
+
+  yield addNewTabPageTab();
+  checkGrid("0,1,2,3,4,5,6,7,8p");
+
+  yield blockCell(8);
+  checkGrid("0,1,2,3,4,5,6,7,9");
+
+  // we remove the first site on the grid with the last one pinned. all cells
+  // but the last one should shift to the left and a new site fades in
+  yield restore();
+  yield setLinks("0,1,2,3,4,5,6,7,8,9");
+  setPinnedLinks(",,,,,,,,8");
+
+  yield addNewTabPageTab();
+  checkGrid("0,1,2,3,4,5,6,7,8p");
+
+  yield blockCell(0);
+  checkGrid("1,2,3,4,5,6,7,9,8p");
+}