Add failing test for reopening causing "Could not satisfy length"

[jmatsushita]

Hi there,

I've bumped into the following error:

Error: Could not satisfy length
    at RandomAccessIDB._read (http://localhost:54726/bundle.js:160:58)
    at Request._run (http://localhost:54726/bundle.js:7458:42)
    at drainQueue (http://localhost:54726/bundle.js:7511:48)
    at Request._unqueue (http://localhost:54726/bundle.js:7424:25)
    at Request.callback (http://localhost:54726/bundle.js:7429:10)
    at f (http://localhost:54726/bundle.js:6824:25)
    at RandomAccessIDB.onlen (http://localhost:54726/bundle.js:100:14)
    at f (http://localhost:54726/bundle.js:6824:25)
    at IDBRequest.req.onsuccess (http://localhost:54726/bundle.js:314:29)

I'm submitting a reproducer in a test simple-reopen.js. Note that I've had to wrap the reopening in a try/catch block as browser-run would just hang otherwise.

[jmatsushita]

This seems to be because the this.length property is not initialised when opening an existing storage, so the (req.offset + req.size) > this.length check in _read fails.

[utanapishtim4storyboard]

Hey @jmatsushita thanks for opening this PR. I think the issue you are encountering is based on the assumption that the { storage } function exported from test/helpers.js acts like the static storage function implemented on the RandomAccessIDB class itself - it does not. The point of the test helper is to guarantee that even if we use the same filename, we get a totally unique IDB instance so we can test cleanly.

Try swaping { storage } from test helpers with const storage = RAI.storage() and see if that fixes your error.

[utanapishtim4storyboard]

@jmatsushita also, out of curiosity, are you npm installing the git repo? We should probably publish this to npm officially.