Original test: http://mxr.mozilla.org/mozilla2.0/source/dom/indexedDB/test/test_cursor_mutation.html?raw=1 This is a test case *adapted* from a test in Mozilla's IndexedDB test suite. The original test checked cursor mutation while iterating an index cursor (tracked as bug 59822). This test checks whether the cursor mutation is successfully recognized while iterating a straight objectstore cursor. Specifically, it deletes a record that's already been iterated, then adds a record to the objectstore during iteration, then checks that no records were skipped and that the added record is eventually found during iteration. WebKit passes this test.