public void PropagatesExceptions()
{
AFnImpl fn = new AFnImpl();
fn._fn0 = () => { throw new Exception("future exception"); };
Future f = new Future(fn);
try
{
f.deref();
Assert.Fail("expected future exception");
}
catch (Exception ex)
{
Expect(ex.Message, EqualTo("Future has an error"));
Expect(ex.InnerException, Is.Not.Null);
Expect(ex.InnerException.Message, EqualTo("future exception"));
}
// Same result for subsequent derefs.
try
{
f.deref();
Assert.Fail("expected future exception");
}
catch (Exception ex)
{
Expect(ex.Message, EqualTo("Future has an error"));
Expect(ex.InnerException, Is.Not.Null);
Expect(ex.InnerException.Message, EqualTo("future exception"));
}
}
public void CachesResultForSubsequentCalls()
{
int i = 0;
AFnImpl fn = new AFnImpl();
fn._fn0 = () => Interlocked.Increment(ref i);
Future f = new Future(fn);
Expect(f.deref(), EqualTo(1));
Expect(f.deref(), EqualTo(1));
Expect(i, EqualTo(1));
}
public void DerefThrowsAfterCancellation()
{
AFnImpl fn = new AFnImpl();
fn._fn0 = () => { while (true); };
Future f = new Future(fn);
f.cancel();
f.deref();
}
public void CancelFailsAfterSuccessfulCompletion()
{
AFnImpl fn = new AFnImpl();
fn._fn0 = () => { return 42; };
Future f = new Future(fn);
Expect(f.deref(), EqualTo(42));
Expect(f.cancel(), EqualTo(false));
Expect(f.isCancelled(), EqualTo(false));
}
public void ComputesTheValueOnAnotherThread()
{
int workerID = Thread.CurrentThread.ManagedThreadId;
AFnImpl fn = new AFnImpl();
fn._fn0 = () =>
{
workerID = Thread.CurrentThread.ManagedThreadId;
return 42;
};
Future f = new Future(fn);
Expect(f.deref(), EqualTo(42));
Expect(workerID, Not.EqualTo(Thread.CurrentThread.ManagedThreadId));
}