Write stubbed test: update begin -> ack
Write stubbed test: update begin -> prep
Write stubbed test: update begin -> update ready
Write stubbed test: chunk -> ack
Write stubbed test: chunk -> chunk received ok
Write stubed test: chunk -> chunk received bad
Write stubbed test: event loop saves received chunk
Write stubbed tests: update done -> ack
Write stubbed test: update done -> finish
Write stubbed test: chunk missed on timeout
Merge pull request #23 from spark/write-stubbed-tests

Write stubbed tests