Add parse_duration fuzzing (via Casper Meijn)

fuzz/common/src/lib.rs

@@ -86,6 +86,32 @@ pub fn test_parse_date(data: &[u8]) {
     );
 }
 
+pub fn test_parse_duration(data: &[u8]) {
+    use std::str::from_utf8;
+    use std::str::FromStr;
+
+    // input must be text
+    let Ok(original_text) = from_utf8(data) else {
+        return;
+    };
+
+    // parse input as a duration
+    let Ok(duration) = bilrost_types::Duration::from_str(original_text) else {
+        if original_text.ends_with("s") {
+            assert!(
+                original_text.parse::<f64>().is_err(),
+                "bilrost failed to parse duration, but it seems to be a valid number: {}",
+                original_text
+            );
+        }
+        return;
+    };
+
+    // roundtrip to and from string
+    let roundtrip_text = format!("{duration}");
+    assert_eq!(Ok(&duration), roundtrip_text.parse().as_ref());
+}
+
 enum RoundtripResult {
     /// The roundtrip succeeded.
     Ok(Vec<u8>),

fuzz/fuzzers/parse_date_fuzz.rs

@@ -1,8 +1,9 @@
 #![no_main]
 
-use common::test_parse_date;
+use common::{test_parse_date, test_parse_duration};
 use libfuzzer_sys::fuzz_target;
 
 fuzz_target!(|data: &[u8]| {
     test_parse_date(data);
+    test_parse_duration(data);
 });