diff --git a/src/modes/mod.rs b/src/modes/mod.rs
index a29dd89..f5c9074 100644
--- a/src/modes/mod.rs
+++ b/src/modes/mod.rs
@@ -14,6 +14,10 @@ pub trait Hand {
 
 mod tests {
     use super::*;
+
+    /** Given two hands, assert that their footstool condition is non-reflexive.
+     * Return the results of the two footstool checks (x on y, y on x).
+     */
     pub fn test_non_reflexivity<T: Hand + Copy>(
         x: &T,
         y: &T,