diff --git a/src/bin/flat/riemann.rs b/src/bin/flat/riemann.rs
index a06ae24..afc4b7b 100644
--- a/src/bin/flat/riemann.rs
+++ b/src/bin/flat/riemann.rs
@@ -169,11 +169,12 @@ pub mod samples {
 
 #[cfg(test)]
 mod tests {
+	use approx::assert_abs_diff_eq;
+	use super::*;
+
 	use glam::{Mat2, mat2, vec2};
 	use rand::{Rng, SeedableRng};
 
-	use super::{Decomp2, Metric, samples};
-
 	#[test]
 	fn uniform_scaled_metric() {
 		let mut rng = rand_pcg::Pcg64Mcg::seed_from_u64(17);
@@ -192,4 +193,16 @@ mod tests {
 		assert_eq!(metric.globalize(rng.gen(), vec2(0., 1.)), vec2(0., 1. / 4.));
 		assert_eq!(metric.globalize(rng.gen(), vec2(1., 1.)), vec2(1. / 3., 1. / 4.));
 	}
+
+	#[test]
+	fn test_trace_iter() {
+		let metric = samples::ScaledMetric { scale: vec2(2., 4.) };
+		assert_eq!(trace_iter(&metric, vec2(3., 5.), vec2(1., 0.), 1.).nth(7).unwrap(), vec2(7., 5.));
+		assert_eq!(trace_iter(&metric, vec2(3., 5.), vec2(2., 0.), 1.).nth(7).unwrap(), vec2(7., 5.));
+		assert_eq!(trace_iter(&metric, vec2(3., 5.), vec2(1., 0.), 0.5).nth(7).unwrap(), vec2(5., 5.));
+		assert_eq!(trace_iter(&metric, vec2(3., 5.), vec2(0., 1.), 1.).nth(9).unwrap(), vec2(3., 7.5));
+		assert_eq!(trace_iter(&metric, vec2(3., 5.), vec2(0., 4.), 1.).nth(9).unwrap(), vec2(3., 7.5));
+		assert_eq!(trace_iter(&metric, vec2(3., 5.), vec2(0., 1.), 0.5).nth(9).unwrap(), vec2(3., 6.25));
+		assert_abs_diff_eq!(trace_iter(&metric, vec2(3., 5.), vec2(0.5, 0.25), std::f32::consts::SQRT_2).nth(7).unwrap(), vec2(7., 7.), epsilon=1e-5);
+	}
 }