static async Task Main()
{
var wordsToCount = new[] { "war", "peace" };
var dataSource = new FileDataSource("WarAndPeace.txt");
var wordCountService = new WordCounterService(dataSource);
var warCount = 0;
var peaceCount = 0;
var linesProcessed = 0;
var progress = new Progress <int>(n => linesProcessed += n);
await foreach (var update in wordCountService.GetWordCountUpdates(wordsToCount, CancellationToken.None, progress))
{
if (update.Word == "war")
{
warCount += update.OccurrencesCount;
}
else
{
peaceCount += update.OccurrencesCount;
}
Console.SetCursorPosition(0, 0);
Console.WriteLine($"Lines processed: {linesProcessed} war: {warCount} peace {peaceCount}");
}
}
async Task <List <WordCountUpdate> > GetWordCountUpdate(params string[] wordsToCount)
{
var result = new List <WordCountUpdate>();
await foreach (var update in m_WordCounterService.GetWordCountUpdates(wordsToCount))
{
result.Add(update);
}
return(result);
}
public void GetWordCountUpdates_DataSourceThrowsAndException_RethrowsTheException()
{
async IAsyncEnumerable <string> StreamData()
{
await Task.FromException(new IOException("hard disk is corrupted"));
yield break; // otherwise compiler will complain "not all path return a value"
}
var dataSource = new Mock <IDataSource>();
dataSource.Setup(x => x.GetData()).Returns(StreamData);
var service = new WordCounterService(dataSource.Object);
var firstUpdate = service.GetWordCountUpdates(new[] { "foo" }).FirstAsync();
Assert.That(async() => await firstUpdate, Throws.InstanceOf <IOException>());
}
public void GetWordCountUpdates_CanBeCancelledAfterItemInStream()
{
var dataSource = new Mock <IDataSource>();
var source = new CancellationTokenSource();
var cancellationToken = source.Token;
async IAsyncEnumerable <string> StreamData()
{
yield return("foo");
await Task.CompletedTask;
}
dataSource.Setup(x => x.GetData()).Returns(StreamData);
var service = new WordCounterService(dataSource.Object);
var enumerator = service.GetWordCountUpdates(new[] { "foo" }, cancellationToken).GetAsyncEnumerator(cancellationToken);
source.Cancel();
Assert.That(async() => await enumerator.MoveNextAsync(), Throws.TypeOf <OperationCanceledException>());
}