Test that Mutation Records are delivered following FileSystem callbacks.
On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
PASS mutations.length is 1
PASS mutations[0].type is "attributes"
PASS mutations[0].attributeName is "foo"
PASS mutations.length is 1
PASS mutations[0].type is "attributes"
PASS mutations[0].attributeName is "baz"
PASS successfullyParsed is true
TEST COMPLETE