Add fuzzing tests

src/fuzzing.rs

@@ -0,0 +1,8 @@
+/// Fuzzing target for simplify().
+///
+/// Calls simplify() and panics if simplify() panics.
+/// Does not return any vaule to avoid exposing internal crate types.
+#[cfg(fuzzing)]
+pub fn simplify(mut input: String, is_chat_message: bool) {
+    crate::simplify::simplify(input, is_chat_message);
+}

src/lib.rs

@@ -117,3 +117,6 @@ pub const DCC_MIME_DEBUG: &str = "DCC_MIME_DEBUG";
 mod test_utils;
 #[cfg(test)]
 mod tests;
+
+#[cfg(fuzzing)]
+pub mod fuzzing;