Add url fuzz target

Author: benalleng

fuzz/Cargo.toml

@@ -29,3 +29,9 @@ name = "uri_deserialize_pjuri"
 path = "fuzz_targets/uri/deserialize_pjuri.rs"
 doc = false
 bench = false
+
+[[bin]]
+name = "url_decode_url"
+path = "fuzz_targets/url/decode_url.rs"
+doc = false
+bench = false

fuzz/fuzz_targets/url/decode_url.rs

@@ -0,0 +1,58 @@
+#![no_main]
+
+use std::str;
+
+use libfuzzer_sys::fuzz_target;
+// Adjust this path to wherever your Url module lives in your crate.
+use payjoin::Url;
+
+fn do_test(data: &[u8]) {
+    let Ok(s) = str::from_utf8(data) else { return };
+
+    let Ok(mut url) = Url::parse(s) else { return };
+
+    let _ = url.scheme();
+    let _ = url.has_host();
+    let _ = url.domain();
+    let _ = url.host_str();
+    let _ = url.port();
+    let _ = url.path();
+    let _ = url.query();
+    let _ = url.fragment();
+    let _ = url.as_str();
+    let _ = url.to_string();
+    if let Some(segs) = url.path_segments() {
+        let _ = segs.collect::<Vec<_>>();
+    }
+
+    let raw = url.as_str().to_owned();
+    if let Ok(reparsed) = Url::parse(&raw) {
+        assert_eq!(
+            reparsed.as_str(),
+            raw,
+            "round-trip mismatch: first={raw:?} second={:?}",
+            reparsed.as_str()
+        );
+    }
+
+    url.set_port(Some(8080));
+    url.set_port(None);
+    url.set_fragment(Some("fuzz"));
+    url.set_fragment(None);
+    url.set_query(Some("k=v"));
+    url.set_query(None);
+    url.query_pairs_mut().append_pair("fuzz_key", "fuzz_val");
+
+    if let Some(mut segs) = url.path_segments_mut() {
+        segs.push("fuzz_segment");
+    }
+
+    let _ = url.join("relative/path");
+    let _ = url.join("/absolute/path");
+    let _ = url.join("../dotdot");
+    let _ = url.join("https://other.example.com/new");
+}
+
+fuzz_target!(|data| {
+    do_test(data);
+});