Add SinceEpoch time to test Scorer hermetically

In order to test Scorer hermetically, sleeps must be avoided. Add a
SinceEpoch abstraction for manually advancing time. Implement the Time
trait for SinceEpoch so that it can be used with ScorerUsingTime in
tests.

diff --git a/lightning/src/routing/scorer.rs b/lightning/src/routing/scorer.rs
index 8b5fae70abdbffa34e6a365f312eb654f5165d84..9df3fbec81104810f9a894d315d730077ccaa568 100644 (file)
--- a/lightning/src/routing/scorer.rs
+++ b/lightning/src/routing/scorer.rs
@@ -247,6 +247,7 @@ impl Time for std::time::Instant {
 }
 
 /// A state in which time has no meaning.
+#[derive(Debug, PartialEq, Eq)]
 pub struct Eternity;
 
 impl Time for Eternity {
@@ -320,3 +321,77 @@ impl<T: Time> Readable for ChannelFailure<T> {
                })
        }
 }
+
+#[cfg(test)]
+mod tests {
+       use super::{Eternity, ScoringParameters, ScorerUsingTime, Time};
+
+       use routing::Score;
+       use routing::network_graph::NodeId;
+
+       use bitcoin::secp256k1::PublicKey;
+       use core::cell::Cell;
+       use core::ops::Sub;
+       use core::time::Duration;
+
+       /// Time that can be advanced manually in tests.
+       #[derive(Debug, PartialEq, Eq)]
+       struct SinceEpoch(Duration);
+
+       impl SinceEpoch {
+               thread_local! {
+                       static ELAPSED: Cell<Duration> = core::cell::Cell::new(Duration::from_secs(0));
+               }
+
+               fn advance(duration: Duration) {
+                       Self::ELAPSED.with(|elapsed| elapsed.set(elapsed.get() + duration))
+               }
+       }
+
+       impl Time for SinceEpoch {
+               fn now() -> Self {
+                       Self(Self::duration_since_epoch())
+               }
+
+               fn duration_since_epoch() -> Duration {
+                       Self::ELAPSED.with(|elapsed| elapsed.get())
+               }
+
+               fn elapsed(&self) -> Duration {
+                       Self::duration_since_epoch() - self.0
+               }
+       }
+
+       impl Sub<Duration> for SinceEpoch {
+               type Output = Self;
+
+               fn sub(self, other: Duration) -> Self {
+                       Self(self.0 - other)
+               }
+       }
+
+       #[test]
+       fn time_passes_when_advanced() {
+               let now = SinceEpoch::now();
+               assert_eq!(now.elapsed(), Duration::from_secs(0));
+
+               SinceEpoch::advance(Duration::from_secs(1));
+               SinceEpoch::advance(Duration::from_secs(1));
+
+               let elapsed = now.elapsed();
+               let later = SinceEpoch::now();
+
+               assert_eq!(elapsed, Duration::from_secs(2));
+               assert_eq!(later - elapsed, now);
+       }
+
+       #[test]
+       fn time_never_passes_in_an_eternity() {
+               let now = Eternity::now();
+               let elapsed = now.elapsed();
+               let later = Eternity::now();
+
+               assert_eq!(now.elapsed(), Duration::from_secs(0));
+               assert_eq!(later - elapsed, now);
+       }
+}