Moddy the Tube test

src/bin/flat/tube/metric.rs

@@ -49,8 +49,14 @@ impl Metric for Tube {
 	}
 }
 
-#[test]
-fn test_tube_metric_derivs() {
+#[cfg(test)]
+mod test {
+	use glam::{Vec2, vec2};
+	use crate::riemann::{Decomp2, Metric};
+	use super::Tube;
+
+	#[test]
+	fn test_tube_metric_derivs() {
 		struct Approx(Tube);
 		impl Metric for Approx {
 			fn sqrt_at(&self, pos: Vec2) -> Decomp2 { self.0.sqrt_at(pos) }
@@ -74,4 +80,5 @@ fn test_tube_metric_derivs() {
 				assert!(eq, "Bad derivative computation at {pos}:\n  explicit:  {computed:?}\n  numerical: {reference:?}\n");
 			}
 		}
+	}
 }