add testing option to count the number of matched messages

[tcoopman]

In my test I sometimes want to check that there is only one message enqueued and not more. A method to test for this would be great.

[sorentwo]

I've thought about this a bit today and I believe both #25 and #26 can be accomplished with the addition of a get_enqueued/1 function. Within tests you would use it like this:

# Make an assertion that there is a single job with the args `%{id: 1}`
assert [%{args: %{id: 1}}] = get_enqueued(worker: MyWorker, queue: "foobar")

# Make an assertion that there is exactly one matching job
assert [%Oban.Job{}] = get_enqueued(worker: MyWorker, queue: "foobar")

This is flexible and allows you to make any assertions that you like in your tests.

[tcoopman]

That sounds very fine

[sorentwo]

Thanks for the suggestion. Between the pattern matching suggestion here and in #25 I believe it is possible to write more robust (though verbose) tests when necessary.

Please take a look at 3c5ed47 and let me know if it works for you.

[tcoopman]

Thanks, this is perfect. I've already tested it, and it works great.