public void when_a_document_crashes_during_an_update_the_previous_version_is_still_available()
{
var rnd = new Random();
// Cause a power-off like failure when writing a document.
// We simulate this with a custom stream
var baseStream = new MemoryStream();
var stream = new CutoffStream(baseStream);
var subject = Database.TryConnect(stream);
// Write a good document, then a failure
subject.WriteDocument("repeat", MakeTestDocument());
stream.CutoffAfter(rnd.Next(10, 900));
try {
subject.WriteDocument("repeat", MakeTestDocument());
} catch {
// Ignore
}
Assert.That(stream.HasCutoff(), Is.True, "Failed to break output stream");
// Load a new database from the truncated data
baseStream.Rewind();
var rawResult = baseStream.ToArray();
var newStream = new MemoryStream(rawResult);
var result = Database.TryConnect(newStream);
var ok = result.Get("repeat", out var resultData);
Assert.That(ok, Is.True, "Fully written document was lost");
var temp = new MemoryStream();
resultData.CopyTo(temp); // this will cause each page's CRC to be tested.
}
public void crashing_half_way_through_a_write_results_in_no_document_added_but_a_readable_database()
{
var rnd = new Random();
// Cause a power-off like failure when writing a document.
// We simulate this with a custom stream
var baseStream = new MemoryStream();
var stream = new CutoffStream(baseStream);
var subject = Database.TryConnect(stream);
// Write a good document, then a failure
subject.WriteDocument("successful", MakeTestDocument());
stream.CutoffAfter(rnd.Next(10, 900));
try {
subject.WriteDocument("failure", MakeTestDocument());
}
catch (Exception ex) {
Console.WriteLine("Exception was triggered, as expected: " + ex.Message);
}
Assert.That(stream.HasCutoff(), Is.True, "Failed to break output stream");
// Load a new database from the truncated data
baseStream.Rewind();
var rawResult = baseStream.ToArray();
var newStream = new MemoryStream(rawResult);
var result = Database.TryConnect(newStream);
var ok = result.Get("successful", out _);
Assert.That(ok, Is.True, "Fully written document was lost");
ok = result.Get("failure", out _);
Assert.That(ok, Is.False, "Partly written document was loaded without an error");
}