Add some tests for `Rect`

crates/emath/src/rect.rs

@@ -680,3 +680,22 @@ impl Div<f32> for Rect {
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_rect() {
+        let r = Rect::from_min_max(pos2(10.0, 10.0), pos2(20.0, 20.0));
+        assert_eq!(r.distance_sq_to_pos(pos2(15.0, 15.0)), 0.0);
+        assert_eq!(r.distance_sq_to_pos(pos2(10.0, 15.0)), 0.0);
+        assert_eq!(r.distance_sq_to_pos(pos2(10.0, 10.0)), 0.0);
+
+        assert_eq!(r.distance_sq_to_pos(pos2(5.0, 15.0)), 25.0); // left of
+        assert_eq!(r.distance_sq_to_pos(pos2(25.0, 15.0)), 25.0); // right of
+        assert_eq!(r.distance_sq_to_pos(pos2(15.0, 5.0)), 25.0); // above
+        assert_eq!(r.distance_sq_to_pos(pos2(15.0, 25.0)), 25.0); // below
+        assert_eq!(r.distance_sq_to_pos(pos2(25.0, 5.0)), 50.0); // right and above
+    }
+}