public async Task Differ_works()
{
var differ = new Differ(CONN_STR, KEY_PREFIX);
// cache is empty. shouldn't be any diffs, but more importantly it shouldn't throw any errors
(await differ.GetPreviousNotInCurrentAsync()).Should().BeEmpty();
(await differ.GetCurrentNotInPreviousAsync()).Should().BeEmpty();
// load day 1. all should be current not in previous, none vice-versa
await differ.LoadCurrentAsync("day1", GetCsvDay1());
(await differ.GetPreviousNotInCurrentAsync()).Should().BeEmpty();
(await differ.GetCurrentNotInPreviousAsync()).Should().HaveCount(7);
// load day 2. should return correct diffs compared to day 1
await differ.LoadCurrentAsync("day2", GetCsvDay2());
(await differ.GetPreviousNotInCurrentAsync())
.Select(s => s.Substring(0, 4))
.Should().BeEquivalentTo("0001", "0003", "0006");
(await differ.GetCurrentNotInPreviousAsync())
.Select(s => s.Substring(0, 4))
.Should().BeEquivalentTo("0001", "0006", "0008");
}