day(20): fix tests

Only one part has a test case.

Signed-off-by: Matej Focko <me@mfocko.xyz>

src/bin/day20.rs

@@ -224,4 +224,14 @@ fn main() -> Result<()> {
     Day20::main()
 }
 
-test_sample!(day_20, Day20, 11687500, 0);
+#[cfg(test)]
+mod day_20 {
+    use super::*;
+
+    #[test]
+    fn part_1() {
+        let path = Day20::get_sample(1);
+        let mut day = Day20::new(path);
+        assert_eq!(day.part_1(), 11687500);
+    }
+}